TDS And Conductivity (EC) Test... and the Anoxic Filter vS Lake Michigan water.

TDS And Conductivity (EC)

In case you're not that familiar with the definitions of TDS (Total Dissolved Solids) and EC.  TDS is read in ppm and refers to the total amount of a substance that is in water besides H2O and EC refers to the electrical charge of the water. EC is read as µS {one millionth of a second} and will tell you how many ions you have in your water most being positively charge and how conductive the water is. For example: You can have water were the turbidity of the water is so bad that you can’t see more than 1” into it, yet the EC reading could be as low as 2-µS. In other words, the water can be full of a insulting substances, yet still EC reading will be so low that electricity would not be able to travel through it and you would not get shocked. 

According to the U.S. EPA and the World Health Organization (WHO) drinking water taste good to humans @ a TDS that’s less than 500-ppm and no greater than 1000-ppm but will taste its best at a TDS of 150-ppm to 250-ppm because TDS will influence taste not EC. However, for Cyprinus carpio and most fish, these numbers really don’t mean that much depending on the fish’s geographical location. Some fish like a high TDS like African Cichlids and others like in the Amazon are never exposed to anything higher than a TDS of 20-ppm. Yet if anyone has seen some of these rivers in the Amazon they are as murky as they get.

There are many things in our ponds that will make the TDS go up or down depending on the insults and how harmful they are to our animals’. Remember, just because you can’t see your Koi in turbid water, doesn’t mean you have a high TDS. The first thing they say on Koi forums is that high TDS will change the turbidity of your pond water; but this however is not true because one has no correlation with the other. Saltwater has a very high TDS and it's Gin clear! A low TDS does not mean you will also have a low EC; it may be higher than the TDS because of more ions in solution, which make it more conductive.

Okay, now that you’re all confused from what you have read on Koi forums on the internet about TDS and no one told you about EC: What does all this have to do with water quality? A lot! You have to know how to read conductivity meters TDS and its CE correctly. If CE is too high then you have an overabundance of free ions in solution and ORP will be lower and the problem needs to be corrected. If TDS is too high then this may be telling you of water quality problems, too. Yet, if you don't know what is causing the increase in TDS, how do you know what to fix? Too many ions in solution can cause TDS to go up too. Now how do you get ions out of solution except with large water changes and is the replacement water also high in ions? If so how do you get them down? We know by adding more oxygen to a solution (like with an Oxygen Reactor) its ORP will go up but that doesn't do anything for an overabundance of ions CE or TDS. The best answers to all these questions are: To have the right filter to do the right job for your applications. Read my post about the Battaglia's pond and their TDS and CE.

The next four photos are going to show you what the mains water here in Chicago is, that comes from Lake Michigan using the world's largest municipal water treatment plant and the Anoxic Filter pond before a pre-filter cleaning (I do that once a week) with no water changes now far over a month. All test were done @ 3:00 p.m. CST Chicago U.S.A. I also must add that pH was the same in my pond and tap water = pH 7.8.

Before we go on, here is something you may be interested in about Chicago water, though not perfect, it is rated as excellent in terms of drinking water. So good in fact that most bottle water has more bacteria in it than Chicago tap water does; as written up in the Chicago Tribune.

From The Sustainability Studies @ Roosevelt University

QUOTE: From their website.

"Chicago, although it does not disinfect its wastewater before releasing it back into the local waterways, has a pretty sophisticated water treatment system. The world’s largest wastewater treatment plant is located in suburban Stickney, and independent water quality assessments (such as those by the National Resource Defense Council) have rated the area’s drinking water as excellent within the past decade. (Ratings include test for contaminants such as lead and various carcinogens.) The quality of the water coming out of Chicago’s taps usually meets or exceeds the quality of the water people choose to purchase in stores, and it comes without the waste of plastic bottles."

Now See What An Anoxic Filter Can Do!

CITY WATER: As you can see from the photos Lake Michigan’s water is pretty clean and has a very low TDS. I left the water running for over 15-minutes before taking the test.

CITY WATER: CE is high but it tells me that ions are low and this water has a high Redox potential.

CITY WATER: CE is high but it tells me that ions are low and this water has a high Redox potential.

MY POND: The CE of my pond is only 54 µS higher than what came out of the tap and this is month old water in a closed system it also tells me Redox is high.

MY POND: It is only 24-ppm higher than the municipal waters from the tap. I would rate this as excellent water from an Anoxic Filter that’s doing all the work alone.

Most hobbyists will take TDS as the most important reading on a ponds water quality more so than ORP (Redox) readings. But I think all three readings ORP, TDS and EC tell us what is happening with the water quality of our ponds and if evasive action is to be taken to correct any insults that you may find using these parameters.

The next photos will show the TDS and EC readings @ 7:30 a.m. CST Chicago the next day after the pre-filter cleaning - about 12-hrs latter- but still no water change. I think if I did a water change that would give us a false positive reading because I do almost a 50% water change every month. All water samples on the pond were taken at the return water from Anoxic Filter to the main pond. Turbidity (%<0.3 NTU) as tested in pond 97%.

POND WATER: As you can see doing a pre-filter clean-out really helped bring down TDS, so now the water is identical to the mains tap water from Lake Michigan.
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POND WATER: The EC is just one notch higher than the main tap water supply and demonstrates how effective the Anoxic Filter is in keeping water at drinkable levels without all the expensive filtration equipment that some depend on to keep Koi.

This photo shows the correct way to test the pond water. Never use a plastic container only glass will do for testing and it can be as simple as a class from the house. Glass holds less of a static charge than plastic does that may influence your readings. Make sure that the probe is stabilized before any readings of merit are to be taken. Fill the glass and let stand for at least 5 minutes or longer with the probe in it, then empty and refill glass again to get your final reading of TDS and EC.

  

Well the numbers don’t lie do they?

We have two points of view here; one will say that the water going into the pond to begin with is already exceeding that of most tap water, so why shouldn’t it be that good in the pond, too? The other side will argue that once the water leave’s the tap; all bets are off and there are a lot of variables like biological and chemical insults that will now influence the quality of the pond water.  It doesn’t matter how pristine the water is in the beginning, it can become a pond of death if filtration and pond husbandry are deficient in being adequately executed. This is called pollutant equilibrium or PE for short. It is the amount of pollutants that are going into the system and the amount of pollutants the system can take out adequately by biological processes to sustain water quality that will not deteriorate over a given time. If the filtration system does not do this, then water changes are needed to balance out incoming insults to the solution such as microbial waste.

This sounds very simple in the beginning when your Koi is no bigger than 6” but with feeding twice a day and now you have a 12” Koi within a year or two, that one 12” Koi now equals Ten  6” Koi. The body mass and pollution that Koi makes at that size overwhelms the biological system and either you stop feeding or upgrade your filtration system to keep PE low so TDS and CE stay low, too. If you don’t mind a high water bill then without upgrading your filtration system in some way your wallet will become a lot lighter. It’s your ball and bat, so how do you want to play the game?

If your TDS and CE are higher than mine, then your filter is not doing its job like an Anoxic Filter can and its ORP (redox) will suffer. This is another reason why Koi do better in an Anoxic Filter than that of a Veggie or "Bog" filter, everything works better when you use science to help.

NOTE: ppm - Parts Per Million (same as mg/l) - or one ounce in 7,350 gallons of water.

             ppb - Parts Per Billion ( same as ug/l) - or one ounce in 7,350,000 gallons of water.

             NTU - Nephelometric Turbidity Unit, used to measure cloudiness in drinking
                         water and pond water.

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