Saturday, January 3, 2015

A question was asked: Why do plants make air bubbles?

A question was asked on Google 1 : Why do plants make air bubbles?
Jave Fern AKA: Microsorium pteropus
Photo taken from internet archives

Pearling is when the plants themselves are cover in small pearl like bubbles that glisten in the light, or releasing oxygen bubbles from photosynthesis that look like a sting of small pearls such as the Microsorium pteropus AKA: Java Fern is doing in this video. 

Java Fern is one of the easiest plants to get to photosynthesize with the least amount of light, sometimes as low as 2500-lux will do it. Most plants will need 10,000-20,000-lux and plenty of CO2.

Since Java Fern has the ability to live in very low light, it has adapted to use smaller amounts of CO2 than other aquatic plants have. Look at the video and you will see none of the other plants that require more light and CO2 are photosynthesizing as well.

All plants need carbon dioxide (CO2) to assimilate the nutrients they need from the water to live. The CO2 is mainly a product of bacteria breaking down organic matter and the fish emitting it through respiration. However it is limited, and plants will exhaust its supply very quickly or it will be expelled into the atmosphere from water movement at the surface of the aquarium. The more you agitate the surface of the aquarium the better the CO2 will be gasses off into the atmosphere and the higher your pH will be.

One way to tell if your water is NOT impregnated with enough CO2 is by doing this little experiment. Pour in some carbonated water (Soda water), that’s water impregnated with carbon dioxide for mixing drinks into your planted tank. In about five-minutes you should see bubbles forming on the leaves of the plants if you have enough light that is. Prudence must be taken as not to add too much CO2 at one time. Add a little soda water and wait five-minutes. If no tiny air bubbles form on the leaves then add a little more, but be careful not to add too much.

The best, easiest and safes way to distribute CO2 into an aquarium is with an automatic CO2 system. Trying to do it with a timer sounds easy enough but becomes a pain to monitor CO2 levels all the time and the accuracy is not there.

You will only be gestimating on the number of bubbles to be used in your bubble counter and how well the distributions of those CO2 bubbles are impregnating the waters mass. I know what Drs. Foster & Smith say in their catalog that a semi-automatic CO2 system has no guesswork…but they are wrong! Trust me, we would never use a system like that in a lab or university.

Too little and you’re wasting your time and money, too much and you’ll misuse of expensive CO2 and may kill off its inhabitance by too low or too high of a fluctuating pH. Your pH will be your biggest enemy with a timer by fluctuating out of control. I just found it to be too inaccurate.

On top of all that you may become plague with cyanobacteria then the tank will have to be broken down or Hydrogen Peroxide will have to be use to kill off the cyanobacteria. For me it was just too hard to be gestimating CO2 levels with a timer. What I found out in the long run is I was way off on my bubble counting and CO2 distributing. You will have a significant pH swing between night and day too without a pH controller. One reason is, you don’t know how much CO2 is being gassed off into the atmosphere at the surface of your tank.

A CO2 regulator with solenoid connected to a pH controller is the only way to go for precise distribution of CO2 and the guessing game is then over. You will also save money on unnecessary test kits with a pH controller. About once ever two months you will recalibrate your pH controller probe and you’re go to go for the next two months. You can also forgo a reactor too.

The best way I have found to distribute CO2 in aquariums is with a powerhead. A small powerhead pump like a Cobalt® MJ-400 or a small 400 PRO Marineland® powerhead will do just fine. Bigger powerheads are good for bigger aquariums. Forget about reactors and ceramic CO2 air bubble diffuser (they clog too fast) for optimizing contact time between CO2 and water.

For example: In the bottom of the Marineland powerhead pump where the water intake is, drill a small hole in the intake tube so the CO2 air line can fit in it nice and snug. Now when the powerhead is on it will not only suck up water from the tank but also it will intake the CO2 bubbles. The impeller of the pump will turn the CO2 into very fine bubbles mixing water and CO2 together just like a venturi does for a protein skimmer. Set your bubble counter to about 15-20 bubbles per second. At this rate a 5 lbs bottle of CO2 would last about 3-4 months before refilling is needed.

I get my CO2 bottles refilled at a fire extinguisher refill center, they also sell CO2 and sell 5 lbs CO2 bottles or bigger if you want. All CO2 bottles must be recertified ever 5 years for safety.

You will also notice your CO2 will run at night but not as much as at daytime hours. This is because your pH controller is constantly monitoring your waters pH and keeping it from fluctuating. I set my pH at 6.8 on the controller so ammonia will be less toxic to the fish at this pH level.

I hope this helps.

Dr. Novak

If you place the CO2 before the filter, the filter may become air-locked. After the filter and you will not have that problem if I read you right.

 CO2 will have no consequence on bacteria or its reproduction state. Isn’t your pH controller controlling your solenoid to your 5 lbs CO2 tank, so why turn it off at nights? Wouldn’t the pH controller turn it off and on when needed? When you talk about ceramics, are you talking about air stones are the ceramics in a reactor?

If it is ceramics in a CO2 reactor you’re talking about, then yes they are very efficient but that is under 3-5lbs of CO2 pressure like that of an oxygen reactor works. Only then will you get the 99% to 100% as claimed, otherwise a none pressurized CO2 reactor will give you only about 67% of efficiency of impregnating water with CO2 not the 99% as claimed. Those numbers are misleading by manufactures to sell their CO2 reactors to the hobbyist. There’re very good but need to be placed after the filter and not before, because of what I said above with air locking.

 Don’t forget you will have to have plenty of room behind the fish tank for your CO2 reactor! I like my tanks to be as close to the wall as possible for cosmetic reasons. So an in tank powerhead mixing the CO2 can be easily hidden low and out-of-site from onlookers. You do not have to worry about a power outage and water being suck into your reactor and leaking all over the floor. The CO2 line will have a one-way check valve on it so this will never happen in using a powerhead in the tank as I have described for you.

Only a water ceramic trickle reactor is the next best thing to a pressurized reactor and that will depend on its length and contact time, too. This is the reason why you have a separate pump in the fish tank or sump that can be adjusted to allow water and CO2 to mix correctly at a specific flow rate. Once again though, all good ideas have their drawbacks and this is not an excepting to the rule.

You can use a ceramic air stone or diffuser but trust me you’ll be using the powerhead method. Contact time and mixing of the waters mass with CO2 is the trick. If you think about it Joel, mixing or impregnating the water with CO2 is the trick, the better your device does this, the less CO2 is needed, how does the ceramic air stone do this?

As the CO2 bubbles rise to the surface of the aquarium they collect proteins on their surfaces but do not efficiently add CO2 to the waters mass. Think of it as how a protein skimmer works in the same order as that ceramic CO2 stone does. The proteins that collect on the surfaces of the bubbles will hinder the conversion of CO2 to waters mass. Yes it will work, but not an efficient as the 99% as claimed. The providing evidence that I have found is more like in the 30% range would be a more usable number.

Then you have that very fine ceramic CO2 diffuser. Bacteria will begin to clog those microspores with polymeric adhesive and then the efficiency of the stone is reduced due to its clogging. You will either have to bleach the ceramics or buy new ones all the time and replace them every month to run at 100% efficiency.



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