# Bioballs contribution for CO2 level in non CO2 injected tank



## tantaMD (Dec 23, 2011)

Greetings everyone. Its been a long time since my last activity in this forum. For years I tried different kind of hobbies, but planted tank is where I always return. And this forum will always be one of the best information sources for this hobby. 
Right now I'm curious about bioball contribution to CO2 level in NPT tank. In NPT tank and in nature as I know, the CO2 sources mainly come from the breakdown of organic matters by the bacteria in soil. But the difference is the amount of organic matters in nature and in a tank. For example in river the decomposition process happens massively producing a lot of CO2. But the CO2 only got used up by the aquatic plants near the bank of the river, because that's the shallowest area where the sunlight can still penetrate. That's not the case in a planted tank.
So if I'm going to set an NPT with a large circulation (of course i'll try to minimize surface agitation) and in the filter I set some bioballs, then after the NPT matured I doubled the fish food quantities than I usually used in my several previous NPT, will I get much higher CO2 level than I usually achieved with just only soil substrate?
If yes, is there any side effects of this? Thank you before


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## dwalstad (Apr 14, 2006)

tantaMD said:


> I doubled the fish food quantities than I usually used in my several previous NPT, will I get much higher CO2 level than I usually achieved with just only soil substrate?
> If yes, is there any side effects of this?


? I don't see much purpose in adding bioballs to the filter in an NPT or why you would do it.

The plants may just grow faster by adding more fishfood to the tank. In nature (most rivers, streams, etc) and NPTs, CO2 is usually a limiting nutrient for plant growth. I wouldn't do anything to remove it.

That said, I don't see any bad side effect to adding bioballs to a _submerged_ filter. The bioballs will just increase bacteria recycling of nutrients.


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## tantaMD (Dec 23, 2011)

dwalstad said:


> The plants may just grow faster by adding more fishfood to the tank. In nature (most rivers, streams, etc) and NPTs, CO2 is usually a limiting nutrient for plant growth. I wouldn't do anything to remove it.


thank you miss walstad for your response. Ecology of Planted Aquarium has been my foundation in building all of my planted tank. 
I'm curious about ways to increase CO2 in NPT because i think it might increase the varieties that can be kept together in NPT. Of course there are many proves that the so called difficult plants can thrive in an NPT. But usually the tank only contains one or two type of plant species. Me my self had grown glossostigma elantinoides in nano NPT with a little val. spiralis.
I'm worried by just doubling the fishfood than I usually does (I already fed them plenty in 2 times a day) there is not enough exposure of the leftover materials to the bacteria to be broken down in time. I'm also worried that it can trigger anaerobic metabolism by the bacteria. 
I think by adding bioballs in a strong circulation filter I can increase the exposure surface in an aerobic condition. 
What's your further thinking about this? thank you


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## dwalstad (Apr 14, 2006)

You have obviously thought this out well, so you're way ahead of me.  The increased surface area of the bio-balls would, indeed, speed up decomposition and CO2 production.

I say go ahead and try it! 

If you get some exciting results, let us know.


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## tiger15 (Apr 9, 2017)

I don't think using bioballs to generate CO2 is a good idea.

First, more bio media do not necessarily get you more bacteria as the bacterial population self adjust to the food source. Once the threshold is reached, any surplus bio media will just be unoccupied. Food is the fuel for CO2 production, not the amount of bio media .

Second, CO2 generated by bacteria under aeroblic condition isn't the same as soil generated CO2 under anaerobic conditions. Under aerobic digestion of carbohydrate or amino acid, every CO2 molecule produced is balanced with an O2 molecule consumed. Overfeeding in an attempt to over produce CO2 to satisfy plants can put your fish at risk by depleting O2. A few hobbyists have experimented adding sugar to a canister to increase CO2 production ended up fouling the water and wiping out all fish. Soil generated CO2 under anaerobic condition does not consume O2, same with CO2 injection by high tech or DIY.

Third, the reason natural waters have more CO2 is because they are open system constantly receiving CO2 saturated groundwater, runoff and rain water. Tank water is a closed system whereby CO2 replenishment by atmospheric diffusion is slow, unless one augment it with injection or soil source.


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## Gerald (Mar 24, 2008)

More info on what Tiger is talking about: https://en.wikipedia.org/wiki/Soil_respiration
In most conditions, the bulk of CO2 respired in soil (from bacteria and plant roots) is aerobically produced. O2 released from healthy plant roots should keeps the soil from getting totally anoxic, and CO2 produced by fermentation is hopefully a minor component.


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## tiger15 (Apr 9, 2017)

Gerald said:


> More info on what Tiger is talking about: https://en.wikipedia.org/wiki/Soil_respiration
> In most conditions, the bulk of CO2 respired in soil (from bacteria and plant roots) is aerobically produced. O2 released from healthy plant roots should keeps the soil from getting totally anoxic, and CO2 produced by fermentation is hopefully a minor component.


True with regard to terrestrial soil the studies reveal, but not so with aquatic soil. Aerobic zone in aquatic soil is superficial, barely penetrates beyond 1/2 inch. Aerobic zone in terrestrial soil is much deeper, in feet in good drained soil with help of humus and earth worms. True that plant roots can deliver O2 to the substrate enlarging the aerobic zone, but only during photo period and won't tax O2 from the water column. Outside the litterol zone, most soil in natural waters have no rooted vegetation, so aerobic CO2 contribution in aquatic soil is minor. CO2 production by Fermentation is a good thing because it doesn't tax O2 in the water column of which diy CO2 is based on.


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## tantaMD (Dec 23, 2011)

Thank you @tiger15 and @gerald for your reply in my thread. I'm sorry i hadn't been able to response in a while. I'm not sure about the bioballs will sucks up O2 to that dangerous level. I think that undergravel filter use the same principle. And also producing co2 by that. Although UGF were not used in a planted tank hobby. But people succeeded in keeping healthy fishes with it until now


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## Gerald (Mar 24, 2008)

It doesn't really matter whether the filter media is bioballs, lava rock, gravel, or foam. The O2 consumed and CO2 produced will be the same, depending on how much ammonia and decomposable organic matter is being produced. That of course depends on the animal load and how much food is going into the system. If the filter media is submerged in water, then O2 must come from diffusion at the water surface or from photosynthesis, and flow rate through the filter must be sufficient to supply the needed oxygen. If it's a trickle filter (media not submerged) then the filter bacteria can easily get all the O2 they need from the surrounding air, so surface O2 diffusion and photosynthesis are insignificant sources, and flow rate is less important.


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## tiger15 (Apr 9, 2017)

Gerald said:


> If it's a trickle filter (media not submerged) then the filter bacteria can easily get all the O2 they need from the surrounding air, so surface O2 diffusion and photosynthesis are insignificant sources, and flow rate is less important.


True, if it is a trickling filter (wet and dry filter), O2 will be extracted from the atmosphere without taxing the water, but then CO2 is driven off through the media. On the balance, there may not be any net gain in CO2..


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## tantaMD (Dec 23, 2011)

CH2O + O2 --> CO2 + H2O is the formula for aerobic decomposition. The other way around is photosynthesis formula. So there is 1 on 1 relation of O2 and CO2. So if the plant biomass is sufficient, we can reduce oxygen depletion in the tank. I think what should be monitored in this setting is the amount and the behaviour of the fishes. If the fishes unhealthy perhaps the oxygen level is not enough for the fishes. Perhaps we can't keep as many fishes as the usual amount people keep in walstad tank


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## tiger15 (Apr 9, 2017)

tantaMD said:


> CH2O + O2 --> CO2 + H2O is the formula for aerobic decomposition. The other way around is photosynthesis formula. So there is 1 on 1 relation of O2 and CO2. So if the plant biomass is sufficient, we can reduce oxygen depletion in the tank. I think what should be monitored in this setting is the amount and the behaviour of the fishes. If the fishes unhealthy perhaps the oxygen level is not enough for the fishes. Perhaps we can't keep as many fishes as the usual amount people keep in walstad tank


A simplified formula for respiration is C6H12O6 + 6O2 > 6CO2 + 6H2O. The reverse is photosynthesis.

So it's a 1 on 1 exchange rate between O2 and CO2, and 1 to 6 demand rate of sugar for O2 known as BOD, an indicator for water pollution. Sugar has a very high BOD, and it doesn't need much to take out all the tank oxygen. I read that someone lost all his fish because his kid dumped a can of soda in his tank.

The formula for aerobic digestion of protein is similar quantitatively for CO2 and O2.

RNH2CHCOOH + O2 = RCOOH + CO2 + NH3

Protein has lower BOD, but is worse in producing toxic NH3 in addition to depleting O2.

Yes, high plant mass can mitigate O2 depletion and NH3 toxicity by photosynthesis, but only helpful during photo period. Respiration continues 24/7.


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## tantaMD (Dec 23, 2011)

Thank you very much tiger15. You have gave a thorough information and brings another enlightment for me in this hobby. But i'm still curious why there are only so little if not no reports of oxygen depletion in UGF system. Because it is using the same principle, aerobic decomposition. Is it only about the amount of carbon we put in the tank? I also want to know your opinion if i also turn off the filter as i turn off the light, will that be at least partially solve the concern you stated?


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## mistergreen (Mar 3, 2007)

Interesting you mentioned O2 depletion when adding sugar. A soda can has like a few tablespoon of sugar so it's not a little especially in a small tank like 10g. The same O2 depletion when adding similar compounds like glut, excel. I add glutamate and mannitol in my tank at a low concentration for carbon. (1/4 tsp in a 75g)

I've killed a few O2 sensitive loaches by overdosing excel in combating bba.


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## tiger15 (Apr 9, 2017)

tantaMD said:


> But i'm still curious why there are only so little if not no reports of oxygen depletion in UGF system. Because it is using the same principle, aerobic decomposition. Is it only about the amount of carbon we put in the tank? I also want to know your opinion if i also turn off the filter as i turn off the light, will that be at least partially solve the concern you stated?


You don't hear much about UGF because very few people use it today. The last time I used it was when I was a kid. UGF will eventually get clogged up and need to be broken down for cleaning, tons of work. Canister filter is essentially an external UGF, easier to clean relative to UGF, but still more work than cleaning HOB or sump filters.

Yes, UGF or equivalent canister can go anaerobic in a power outage if it is gunk up. When power resumes, it can flush out toxic NH3 and H2S generated during power outage. Although wipe outs from dirty canister were rarely reported, more likely, if it happened, the cause was unidentified because the evidence is gone upon power resumption and subsequent reoxygenation. During long power outage, it's a good idea to open up the canister and clean it before power resumption. Many who did it notice sulfide smell.

Traditional UGF runs by low flow air lift pump isn't as vulnerable to power surge disaster because it doesn't have enough power to flush out toxic gases in big slugs. Years ago a fish friend of mine had a wipe out he could not identify the cause. He kept African cichlids with power head driven UGF, so in retrospect, I speculate that his wipe out was caused by dirty UGF in a power surge he was not aware of. So your idea to shut down the filter during light out is a dangerous proposition.

Not just carbohydrate, protein is also a source of BOD and generator for CO2 (also NH3) . The only way to add CO2 without taxing O2 in the tank water is to place sugar in a separate chamber. The set up is similar to a DIY CO2 except that CO2 is not generated by anaerobic fermentation but aerobic digestion of sugar by injecting air into the chamber. I have been contemplating the idea but never tried it out so don't know if it will work.


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