Wednesday, January 28, 2015

The conditions of the Koi’s are healthy and quite bulky but not yet as bulky as I would like them to be.

E-mail 1-27-2015

Q:  I just got back from a business trip and after a long time once again I was curious on what was new on your blog and stumbled upon the article entitled “Just My Two Cents”. It shocked me when you gave the comparison between 66@15.25cm (6”) koi vs 1@61cm (24”) koi. Since I started using the AFS, as you know, my pond conditions have improved significantly thus my koi have been developing well. As a result now I have 12 koi at an average size of 50cm (20”) in only a 3-ton pond. This then made me wonder whether my 31 BCB baskets are still sufficient for the load. My baskets are smaller than yours, only 25 cm (10”) in diameter and about 15 cm (6”) in height.

So far my concern is mechanical filtering but I’m still on top of the maintenance and cleaning. I feed my koi approximately 5kg (11 lbs.) per month of hi protein food (Kenkokanri Hi Silk 21) or approximately 166 gr/ (5.8 oz.) a day. This amount is actually still below the recommended feeding rate of 3-5% body weight per day. As much as I would like to add more food, I think it would do more harm than good, so I restrain myself from doing so.

The conditions of the Koi’s are healthy and quite bulky but not yet as bulky as I would like them to be. My target is to keep them until size 70cm (27.5”) if possible just to see if it is possible, since most average pond owners have small ponds like me, and if this were possible, it would be a huge boost in morale in opposition to those who say it can’t be done.

I do nothing new to the pond anymore, just continuing regular maintenance. Do you think I need to find a way to add more BCB’s to my filtering system for the target of keeping 12@70cm (27.5”) koi in my pond? Again thank you very much for your kind attention.

 PS: During the Christmas and New Year Holiday season, some koi in the pond spawned. I was out of town on vacation so there was only my housekeeper left instructed to do one water change @10% per day while the koi were fasting since I left. The system held up, nothing bad happened, not even a sick koi. Water clarity restored in a couple of days.  If I were there, I would have done a major water change. The AFS really did its magic, giving me extra comfort when I must leave town.

 Thanks again Dr. Novak.

 I thought I would share this e-mail because it brings up some good questions along with some respectable problems that face koi hobbyist with smaller ponds. Not everyone has room for a big pond but that should not stymie those that are interested in keeping Koi. Even though everyone says the “larger the better” that does not always mean it’s written in stone when using an AFS.  With a conventional filtration system it could present a problem because filters must be overkill and smaller ponds lacking that versatility of room and high output pumps because the filters being governed by pump output. The AFS gives you a larger filter and the GPH pump that is needed for such smaller ponds for quicker turn over times. Larger ponds can get by with slower turn over volumes due to mass of water to fish load.

The hobbyist that sent me this e-mail is lucky, in that, in their country weather conditions are more Koi growth friendly than our weather is in the northern U.S. states. Unless you’re willing to pay for heating and high electric bills or gas bills for your pond; most Koi ponds are in a standby mode until early springtime when weather conditions permits for a normal feeding regime once again to begin. The winter months become an inhibitor for our Koi’s growth rate and it may take more years than anticipated for any larger size Koi to reach that 70cm (27”) mark compared to a country that has ideal conditions all year long.

However, that is only one component that plays a part in Koi growth rate and the size of the pond and feed rate or should I say food quantity per given day, will also be a controlling factor. Some of the better-off Koi keepers here in the U.S. will send their fish off to grow-out ponds for $500-700 USD a year to get most of their size on their fish before bringing them home to finish them off. They may gain as much as 4-6” a year in these million gallon ponds.

 Twelve Koi in a 3-ton pond (705 US gals) @ 50cm (20”) is already pushing the ponds limits. It is highly recommended in books and anecdotal accounts by other hobbyists that hobbyist give at least 500-gals of water per Koi and even this number is too low and should be twice that per fish. But you will seldom see these numbers of Koi to water capacity ever being adhered to by hobbyist. This is what my article on “Just My Two Cents Worth” was all about. 

 Nobody sticks to the guidelines that are given with ponds or aquariums for fish to water volume stocking rates for that matter.

Nonetheless, the game changer is the AFS that the hobbyist is using on their pond and this will push those numbers of water volume per Koi mass lower.  This has been proven time and time again with hobbyist and myself along with the beta testing pond in our experiments. I’m talking about water quality here not elbowroom. Though I never condone overcrowding and I’m guilty of those sins myself, I know that through proper pond husbandry and an AFS all things do not become equal comparing it to a conventional filtering system.

Even a spawning of the Koi in this 3-ton pond with very modest 10% water changes, the animals came out without any adverse health effects.  This is a good sign that the AFS is doing its job and a good indicator that the hobbyist is doing their job as well.

Getting to answering the hobbyist question instead of me rambling on:

 A: The question of adding more BCB’s is a legit concern because of the smaller size of 25cm X 15cm round (10”x 6”) BCB’s than the recommended size of 11”x11”x7” which will carry billions of cells more for chemical and biological processes to take place. In order to increase feeding more BCB’s will have to be added but room to add more of them seem to be the problem. It’s just too bad that you don’t have the available space to add a bigger AFS.

I have had 17 large koi in a 1200 gal (4,542.5 L) (5.1 ton) pond with four of them being 29-30” and the rest in the 16-24” range. I even show photos of them on my blog. But them my AFS is bigger than yours (8'x4'x2' deep) and my BCB’s are larger too. It’s doable to have 12 Koi @ 70cm but feeding them more without a larger filter will become the problem. The larger filter will add needed volume to your waters mass, too. Your mechanical prefilter will have to be top notch. If you can accomplish this, you will be the envy of other Koi keepers in your country.

Here is an old photo of the Koi I was talking about in my pond. The smallest one is16" in the background and the rest in the foreground are 20" and larger. So, it is doable to have large Koi in a small pond using an AFS.

Brian Woodcock in the UK is a prime example of how well his Koi are doing in his pond that should have far less Koi in it. He is already thinking of modifying his AFS this spring once again to a MK II AFS filter (1). I can’t wait to see his new modifications to his Mk II. It should make for some very interesting reading and photos this summer.

(1) [ED: I do not know what a MK II AFS filter modification is as of yet so we will see when Brian’s done with his filter. I know that I have found some really nice 1 x 1” square black PVC pipes at Lowes to place on the bottom of my filter. These hollow square pipes will lift the BCB’s off the filters bottom and make it easier for filter cleaning. This will be my project for this year and I will take photos to show the details. Being that these will already be black and square, it will make installation easier with less prep time involved.]

Sunday, January 25, 2015

Cyanobacteria…what is it, and can we get rid of it very easily?

Cyanobacteria…what is it, and can we get rid of it very easily?

The short answer is NO! Once it plagues your pond or fish aquarium it’s there to stay. If you want to use the word it’s very contagious, then it would be rightfully so. It is in every water biotope in the world and it’s one bacterium that is next to impossible to totally get rid of completely. Even with antibiotics it will eventually become resistant to them and become a super bug.

It has the capabilities to photosynthesize and gets it energy through such. It’s prokaryotic and it is known to be the earliest form of microorganism life on the planet, better known as Blue-Green Algae (a filamentous form of algae) or String Algae, which is a misnomer used for its name. The chloroplasts found in higher order plants and eukaryotic algae all evolved from cyanobacterial ancestors by means of endosymbiosis. 

If left unabated it can grow to several feet long and cover everything in sight. It can and will make a beautiful pond and/or aquarium look unsightly to onlookers. It will cover and smothers any competing plant life it clings to including saltwater inhabitants like in mini-reef aquariums. It takes no prisoners and makes everything its breeding ground. The older your system is (pond or aquarium), the better it likes it.

Normally a newly set up aquarium is not plagued with this bacterium, but as it ages then all bets are off. Even with proper maintenance and water changes it will eventually show up.

The small 5-gal experimental aquarium in the next eight photos is now over two years old. It has been cleaned up some with the cropping of the cyanobacteria long thread like stands before disinfection takes place.  Through the 8-day pictorial history you will be able to see just how one tablespoon of Hydrogen Peroxide @ 3% solution will bring this bacteria under control and yet not hurt the higher order of plants or its inhabitance.

Hydrogen Peroxide is a very strong oxidizing liquid/chemical that when use in an aquarium and/or pond reacts like Ozone can and becomes a bacteria disinfectant. Barley Straw actually makes a form of Hydrogen Peroxide that is slowly released through bacteria decomposition of the straw back into solution to help control this nuisance bacterium.

A better way of controlling cyanobacteria is with the antibiotics that are naturally created through the biological filter like that in an AFS. The problem is as filters age (clog) their ability to create enough of these antibiotic substances are lessen. In the pond this could be because of a change in weather conditions that will in turn affect the filter ability to produce these antibiotic in greater numbers to adversely influence the cyanobacterial growth. In the aquarium the filter also plays the same role but the gravel and available foodstuffs may become more assessable to the cyanobacteria to get a better stronghold in such a small confined space.

A lot of hobbyists believe the competition of available foodstuffs with higher order plants will be too competitive for cyanobacteria to grow, but they are wrong. Many algae’s along with cyanobacteria will begin to form on plant leaves as the tank or pond ages. Caridina multidentata AKA: Amano Shrimp from Japan may be a good Band-Aid at first for some of the algae’s but not all and definitely not for cyanobacteria.  The plethora of different algae’s can overwhelm the hobbyist into submission if evasive action isn’t taken immediately to rectify the problem. 
So, with each monthly water change a little Hydrogen Peroxide added to the replacement water will go a long way in keeping cyanobacteria under control.
Day one, Hydrogen Peroxide is added.

Day two.
Day three.
Day four.
Day five.

Day six.

Day seven.
Day eight.

Not 100% gone but under control.

Sunday, January 18, 2015

QUOTE: “I don't understand. He says in his answer to a readers question that "the more water changes the better" (up to a point).”

QUOTE: “I don't understand. He says in his answer to a readers question that "the more water changes the better" (up to a point).”

I can see that some hobbyist are confused over the fact that water changes, how much to be taken out and when there carried out can make a big difference in Pollutant Equilibrium (or PE for short) in an aquarium or pond.

The example I’m going to give will show two hobbyists, one we will call hobbyist A and the other hobbyist B. Now hobbyists A will do their water changes every week at a rate of 10% per water change. Hobbyists B on the other hand will do their water changes only once a month at a rate of 40% which equals hobbyists A’s weekly water changes in that same four week span. Does everyone follow me here (10% x 4 weeks or one month = 40%) adjustments will be made for months that have five weeks in them for both hobbyists.

Both hobbyists have aquariums @ 50-US gals and the amount of NO3 being produced by the bacteria will be at a constant of 8-ppm per week for both aquariums. The question is: Will hobbyists A be better productively than hobbyist B because they do more water changes and weekly instead of letting the insults rise too high in a given month?  After all 8-ppm looks a lot better than 32-ppm that hobbyists B has to contend with every month.

This is one thing (water changes) that becomes debatable when in discussion groups and/or forums on the more frequent you do water changes it’s always better than a once a month water change because you do not allow pollution to rise too high in a given time span, right? Wrong! The math shows different! In fact you’re wasting your time and water doing it every week.

Hobbyists A weekly water changes:

Week 1= 8ppm NO3 -10% water change far that week = 7.2ppm of NO3 left for the next weeks water change to contend with plus the 8ppm NO3 that the system will produce for the coming week.

Week 2=(8ppm + 7.2ppm) -10% = 13.68ppm of NO3
Week 3=(8ppm +13.68ppm) -10% = 19.51ppm of NO3
Week 4=(8ppm + 19.51ppm) -10% = 27.51ppm of NO3
Week 5= (8ppm + 27.51ppm) -10% = 31.95ppm of NO3
Week 6= (8ppm + 31.95ppm) -10% = 35.96ppm of NO3
Week 7= (8ppm + 35.96ppm) -10% = 39.56ppm of NO3
Week 8= (8ppm + 39.56ppm) -10% = 42.81ppm of NO3
Week 9= (8ppm + 42.81ppm) -10% = 45.73ppm of NO3

I will stop here because this now shows over two months of water changes and should give us a good idea that NO3 just keeps escalating if not unabated by other means soon.

Hobbyists B monthly water changes:

First months water change will have to contend with 32ppm NO3 because every week it increased by 8ppm. So… 4 x 8ppm = 32ppm of NO3, right?
32ppm – 40% water change (this makes the same as hobbyist A did in a four week span) =19.2ppm NO3 still left.
Month 2= (8ppm x4) + 19.2ppm) -40%= 30.72ppm of NO3
Month 3= (8ppm x4) + 30.72ppm) -40% = 37.63ppm of NO3
Month4= (8ppmx4) +37.63ppm) -40% = 41.77ppm of NO3
Month5= (8ppm x 4) + 41.77ppm) -40% = 44.26ppm of NO3
Month6= (8ppm x 4) + 44.26ppm) -40% = 45.75ppm of NO3

As you can see Hobbyists A after just 9 weeks of 10% water changes is at the same level of NO3 as hobbyists B is after 6 months of water changes @ 40% per month. There’s no debating it, the math does not lie; water changes must be conducted larger than 10% if you really want to do any good to lessen the insults in your aquarium and/or pond.

The only way to lessen water changes in a closed system is with an Anoxic Filtration System.

Saturday, January 17, 2015

And all of you thought the AFS was only for ponds and aquariums…now the Aquaponics crowd is getting into it.

A Quote from Aquaponics Nation web site…

“So here is how I figured out how much water change I need to maintain the 200mg/L nitrogen level.. I am not getting the exact same number as you Paul so if I have missed something please correct me.. Thanks.

We have a Fish tank (1500L) that has accumulated a 200ppm TAN level. 

This tank is getting 11.776 grams of TAN per day based on 400grams feed and a 32% Protein content.

So 400*0.32*0.092= 11.776 Grams of TAN (total ammonia nitrogen)
As explained by Paul and in the Timmons book, Nitrogen doesn't magically multiply when it's being oxidized to Nitrate. (should have trusted my gut on that in the first place) The Nitrogen content is still the same, less a fraction that is being absorbed into biomass of the bacteria oxidizing it to nitrates.. But like Paul said, lets not complicate it lets calculate based on TAN (total ammonia nitrogen).

The so we have 11.776g or 11776mg of TAN being added to 1500L of water daily, so 11776/1500= 7.85mg of TAN per liter is added daily.

When time comes to figure out how much water to remove to keep around 200mg/L of nitrogen we have to look @what the level of nitrogen is in the water that we are removing (in this case somewhere between 200 mg/L)  . So the easy way to figure this out would be to take 11776mg/200mg/L = 58.88 Liters.. 

if we want to maintain 200mg/L we have a total of 1500L * 200mg/L = 300000mg of TAN in system. If we remove 11776mg we have 288224mg TAN in the water @ 1500-58.88=1441.12L

If we do 288224/1441.12= 200mg/L But when we add back the 58.88 liters to our system we have 288224/1500L=192.149mg/L as the day moves on 7.85mg/L is added to system, again bringing the total nitrogen content up to 192.15+7.85= 200mg/L

I am sure I am missing some minor detail to get the math exact.. But in my opinion this will be close enough”  

[ED: And all of you thought the AFS was only for ponds and aquariums…now the Aquaponics crowd is getting into it.]

So you really think that 10% water change is doing your pond/aquarium any good…think again!

Here are some excerpts from by blog that may interest the aquarium hobbyists. Just replace the word ‘pond’ with aquarium and the same rules apply.

Koi-Vet Forum Question:

Q: How can two major water changes per year (coupled with replacing losses due to evaporation) possibly deal with the obvious shortcoming of declining water quality -- other than by simply denying that it exists?


A: This is a very good question and deserves an astute answer. I also hope that everyone on Koi-Vet reads this and takes note of this response, especially any of the newer hobbyists in ponding. 

You yourself know about water stability, decline, and the parameters that must be held in order to keep our animals alive and healthy along with water changes. Water quality is always a problem because as time passes, various physical, chemical, and biological processes working in and around the pond alters the initial tabula rasa characteristics of the water. However, not all hobbyists are so inclined to do so, water changes that is, and a number of these people will only do as much or as little, as they humanly possibly can; “getaway with!”   

 With that said; all water changes are dictated by PE (Pollutant Equilibrium). This is the amount of pollutants being made by the system, its animals, plants, the filter, and the amount the water that is exchanged from periodic water changes, will reach what is called a steady state. This also includes the amount of foodstuffs that are being added to the system on a daily bases. The fish food itself, will add nitrogen and phosphates to the system, as you know. The filtration system will be the limiting factor here because of its capabilities or its incapability to process such pollutants on hourly or daily bases. If more pollutants are being made/added to the water body proper than what the execution of a water change can eliminate or lessen to a greater degree, for the safe keeping of our animals, then a larger filtration system is needed. Therefore, larger portion of the water mass must be exchange with clean water, until a PE is then reached. 

 The only reason we execute such water changes is because: No matter what kind of filtration system we use, even a state-of-the-art filtration system, we are still dealing with a closed system. Therefore, a filtration system will not stop the decline of pollution in our ponds, but will only slow it down to some degree, and the degree of degradation is determined by so many factors that it would be anyone’s guess as to what the causes of the insults are and what the outcome would be on the system parameters. Therefore this judgment on water changes will be based on an “individual’s decision,” on when, and how much and why such will be conducted. 

I will also quote right from my free iTunes Book if I may: “Even with the Anoxic Filtration System, as good as it is, still needs to have at least two partial water changes made each year. Generally, the greater proportion of water that is changed during the filter clean-out, the lower the stabilizing pollutant level in the pond would be. Because of this filtration systems capability, the Pollutant Equilibrium levels are reached within a short time-span of weeks instead of months, without all the frustrating water changes and the cost of doing them.” I believe that the hobbyist is reading this one section of my free iTunes Book and taking it to the bank, as to say.  

You must read my whole book and then one can determined that if Nitrates are eradicated and /or diluted to a greater degree by the filter, then water changes for Nitrates (N03) sake, is not a prerequisite for keeping our pond healthy. In fact, I give this as an example in my free iTunes Book: “For example, lets say you have a pond, for the sake of argument will say this pond is 3000 gallons, that is producing 8-ppm (ppm = parts per million) of nitrogen (NO3) every month, this now becomes a constant.” As we all know, Nitrates; are only a small constituent of the amount of pollutants that our ponds have to deal with. In no way did I ever say or advocate in my book, that if you use my system, water changes can be eliminated or that only two water changes a year will suffice, no matter what the pollution equilibrium is or is not! I myself cannot, and will not, second-guess what a ponds pollution mass to insult levels are. In fact I will quote from my book once again: “There is little argument whether or not a periodic partial water change is necessary in order to maintain a healthy pond that fish can live in without undue stress. I also think that all hobbyists would agree that all ponds would benefit from more frequent water changes, and generally this would be “the more frequent the better.” Does this sound like a person that only advocates two water changes a year?  

However, I also must add that there are several hobbyist using the Anoxic Filtration System that only do one too two large water changes a year with excellent results in fish growth, heath, ect., ect., for many years now. Because this is a repeatable constant, there must be some legitimacy into what I say in my book about me only executing two large water changes a year in my testing pond. 

As you have already stated there is more to the pollution picture in a pond than just one end-byproduct of a specific bacterium. Any hobbyist can supersede the filtration capabilities and you and I have no control over that. However, if the pollution constants are, let say, too much food or over stocked pond, no filtration system made for the hobbyist will overcome these insults. Not even the Anoxic Filtration System for that matter. I see this with people using the Nexus system, were they add on supplementary filtration to an already expensive filtration system, just to handle what the filtration system itself cannot. 

 Too many hobbyists that read my free iTunes Book only read the words “still needs to have at least two partial water changes made each year” thinking only; “two partial water changes a year, great!” Of course, that is not what I say at all. As you can see this is the bare minimum that I recommend, and even at the bare minimum, hobbyist that uses this system will not even do that much, believe it or not! My system is good, but it can’t make a silk purse out of a sow’s ear. However, I must interject here with an observation that a 10% water change a week would be useless, if the hobbyist does not know what their PE is to begin with. 

I also stated in my book: “That is excellent for an 18-year-old pond, which has never had a complete water change”. This testimonial was made to let the hobbyist know that a complete teardown (like some system require) of the system has never been executed, in other words; a 100% of its water mass has never been replaced at one time or another.  

I also say in my iTunes Book: “Now let us take for example the Anoxic Filtration System. In the 18 years that I have been experimenting/studying and researching this system, I only clean the filter system twice a year, once in March and another time in late autumn at the end of October. This is the only water change my pond has ever received in 18 years.” Some hobbyists that use this system can and have done the same thing as myself, and some have done even better using this system than I. All I am telling you is what “I have done under controlled conditions in an experimental pond.” I just give you the results that the Beta-testing pond and I have had. After all, I do not know your animals feeding habits, stocking levels, geographical location, or your pond husbandry. Nevertheless, I do say in my iTunes Book to clean the filtration system out at lest twice a year. No filtration manufacture can predetermine what a person will do with their filtration systems 100% of the time, and neither can I for that matter.  

In fact in my iTunes Book, I give an example of one hobbyist that only does two water changes a year and has crystal clear water that will impress the most hardcore hobbyist into acquiescence. However, he does not “over feed” his Koi nor does he “overstock” his pond. The relationship between filter and animal load is in equilibrium with each other. Not all hobbyist fall into this category. 

I also must take 100% of the blameworthiness for my iTunes Book not coming across very clearly to the hobbyist and for that, I make an apology.  



G Day Dr Kevin

I am from Sydney Australia and this year I acquired you Anoxic filtration system from a club member who was getting out of Koi due to ill health.

I placed the baskets in my breeding set up which normally we have high ammonia levels and have to do lots of water changes ,this year no water changes and the fry grew quicker and I was able to double the amount of fish I spawned so am very impressed I would like to acquire your video ( Cd-Book) so as I can share the knowledge, could you please let me know what the cost are including the shipping and if you are down this nick of the woods please let me know yes we are all Koi mad here in Australia.

Regards Gerard,

Chairperson of the northern branch in Australia

Here is my original article on Pollutant Equilibrium (or PE for short). This article definitely encompasses the aquarium hobbyist too.


We own a three thousand-gallon pond and every month we do a 10% water change. We have talked to other hobbyists and some say they do a water change and others say they do not change any of the pond water. My question is: When changing water in a pond how much and how often should it be changed, if at all?


Nature’s waters are abundant in biological materials, ranging from microscopic organisms too large aquatic plants and animals including fish. The presence of plants and animals in the aquatic environment means that there are also organic and inorganic byproducts being mineralize from solid organic materials from living or dead tissue. These breakdown products include humic acid, oils, waxes, assorted hydrocarbons, and fatty acids “all invisible residues that affect water quality. Although, it does not matter whether it is a lake, river, or the vast oceans, the waste generated by fish, our aquatic animals and plants do not accumulate to any significant extent the sheer volume of water of the habitat is diluting it. The pollution concentrations are also eradicated and diluted largely in cases such as rivers and natural pond waters, since freshwater is renewing it constantly through the intersection of topography, being stream-fed with freshwater, rainwater, and meltwater from ice or snow. 

However, the typical ornamental pond operates as a closed recirculation system, with the same water remaining in the pond for weeks or months at a time, even if it rains frequently this will make an insignificant difference. In this situation water quality is always a problem because as time passes various physical, chemical, and biological processes working in and around the pond alters the initial tabula rasa characteristics of the water. 

 In an enclosed ecosystem such as our ponds, a void of an overabundance of plants and ion nutrient users, most hobbyists think they can make their ponds oligotrophic in nature, but this is much harder than one thinks to achieve. Because; most of the time filtration systems are inadequate at the removal of pollutants generated by the inhabitants and clean highly oxygenated water is dependent upon the filtration systems capabilities and the amount of water that is being exchanged by the hobbyists periodically. 

 There is little argument whether a periodic partial water change is necessary to maintain a healthy pond that fish can live in without undue stress. I also think that all hobbyists would agree that all ponds would benefit from more frequent water changes and generally this would be “the more frequent the better.” However, how much water should be renewed and how often should such changes take place are often a matter of discrepancy. Finding unambiguous answers to these questions in hobbyists’ books and monthly periodicals may become a crapshoot at best. Too many hobbyists do not understand the mathematical equations used to determine whether water changes would become beneficial or redundant in an enclosed ecosystem such as our ponds. 

One thing hobbyists must understand is the idiom Pollutant Equilibrium (or PE for short). Pollutant Equilibrium means that the amount of pollutants that are being produced by the animals, plants, filter and the amount the water that is exchanged from periodic water changes will reach what is called a steady state or constant state. This means when a steady income of pollutants are being produced at a given rate and water is being exchanged at a given rate that everything will remain on an equilibrium with each other and nothing will increase or decrease over a given time. If pollutants overshadow the amount of water being exchanged then the amount of pollutants will increase over time to toxic levels even though a constant amount of water is being replaced. This arises due to inadequate filtration systems the hobbyist thought would work for their fish load. 

For example; let’s say you have a pond,  for the sake of argument will say this pond is 3000 gallons, that is producing 8-ppm (ppm = parts per million) of nitrogen (NO3) every month, this now becomes a constant. The hobbyist now wishes to reduce this nitrogen compound by doing a water change on a monthly basis. If the hobbyists were to do a 50 percent water change, this now would halve the amount of pollutants to 4-ppm (0+8)-50%= 4). However, do not forget that every month the NO3 levels will begin again to elevate another 8-ppm. In addition, you must include the NO3 compounds that were remaining from the last water change. The next month will make the pollutant level elevate to 12-ppm before a water change (4+8)-50%=6). The next month after that it will elevate to 14-ppm (6+8)-50%=7) and so on in their pond. It would now take eight months before a PE is then reached.

Then every month afterwards, the Nitrogen compounds being produced, and the amount of water being exchange would be in equilibrium with each other, and would remain at a constant 15.9-ppm NO3 levels or a steady state. As you can see the hobbyists even after conducting a 50 percent water change of 1500-gallons, may still run into problems with cyanobacteria and algae buildup, as green water in the pond. Because their nitrogen compounds have now exceeded the safety margin of keeping nitrates below the 15-ppm limit every month before a water change is executed. 

 If the same hobbyists were only to do 20% water change every month, it would take over sixteen months before a PE would be reached of 39.0-ppm NO3 levels. If the water changes were only 10%, calculation similar to those used above, would show the ensuring situation deteriorating even further, with the pollutants stabilizing at 20 times the amount generated from one water change to the next. Besides, the PE values differing with different extent of water being change the time it takes for PE to be reached also differs. In reality, doing a water change of anything less than 40 percent would be useless in anybody’s pond. The consequences of increasing or decreasing the frequency of water changes or the volume of water replaced on each occasion would only be anyone’s guess. Do to the fact the hobbyists not knowing the exact aleatory nature of the biomass and how much pollutant matter is being generated in a single day of the pond existence. 

Therefore, with the information that we now know regarding the buildup of pollutants and routine partial water changes we can conclude the following. Starting with pure unpolluted water, pollutants in the pond will progressively increase with time, even as partial water changes continue at regular intervals. However, this increased does not continue unabated but stabilize as it reaches PE. The greater the proportion and the shorter the rĂ©gime-time between each renew water change the lower the PE would be and the shorter the time it will take the PE goal to be reached. As you can see, winning the battle against pollutants in an enclosed biotope such as our ponds seems almost to be futile1. This is because the amount of nitrogenous wastes produced is many times greater than the pond’s natural capacity to absorb it.

 However, one of the biggest weapons we have in our arsenal which is in our favor is a well-designed filtration system, which we can implement in the battle against the pollutants. Now we come down to the one big problem that all hobbyists are faced with and that is “the well-designed filtration system.” Since this is easier said than done the hobbyists are left with no other alternative than to do partial water changes in their pond.  

Even with the Anoxic Filtration System, as good as it is still needs to have at least two partial water changes made each year. Generally, the greater proportion of water that is changed during the filter cleanout the lower the stabilizing pollutant level in the pond would be. Because of this filtration systems capability, the Pollutant Equilibrium levels are reached within a short time-span of weeks instead of months, without all the frustrating water changes and the cost of doing them. From what we have learned, the hobbyist that does 10 percent water changes would hardly be worth the endeavor or their valuable time.

1: The fact is that the actual ammonia, nitrite, and nitrate levels in a fully recirculating biotope such as our ponds that requires supplementary biological filtration is never zero “even if the filter design ensures 100 percent inorganic compound removal effectiveness. There is always some trace amount of these compounds in bulk water because the fish are constantly adding ammonia (fish continuously excrete ammonia through their gills, as well as through diluted urine) and other organic compounds to the water body proper. The filter can only remove ammonia and nitrites from that small portion of the pond water that is moving through it at any given time. So, even as one portion of the pond water is being cleansed of these compounds, another part is being polluted at the same time.