Is There Such A Thing As Too Much Co2?

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m00se

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Hi all,

I've just started a new planted tank after not having much luck with my old one. This tank is 290L/75 US gal with a gravel substrate. It's only got about 90W of lighting (T8), and I know that's not really enough, even with reflectors. I'm upgrading to a proper T5 setup when I get paid. I'm also adding ferts once a week after my water changes and I've got CO2 injecting via homebrew method (i.e. into some standard airline tubing from yeast/sugar bottles, plugged into the venturi hose inlet on my powerhead. I have another powerhead pointing towards this one from the other end of the tank, resulting in a circulating effect, and watching the bubbles, they stay suspended in the water for absolutely ages. Currently I'm getting a little puff of CO2 bubbles from my powerhead about once every second or so, probably slightly faster.

I'm aware that CO2 obviously has the potential to lower the pH of my water, but my water from the tap is pH 7.6 and hasn't changed in the week and a half I've been injecting so far. I just wondered if there were any other negative side-effects of injecting CO2. Is there such a thing as 'too much' for the plants?

Thanks in advance for your help :) :good:
 
well if you add too much it can kill your fish by gassing them not sure on plants
 
funny you should say that as im building one as we speak lol im just waiting for the sugar/water solution to cool down before i add the yeast lol
 
well if you add too much it can kill your fish by gassing them not sure on plants

How would I know if I'm gassing the fish? i.e. what would I be looking to test for?

Thanks!
 
Toxicity levels vary depending on the species, the size, and the metabolic rate. The fish’s metabolism is more active in higher temperatures then in cooler environments, which allows toxins to act faster.

Toxic substances come in contact with the fish through the gills, rather than the skin. This allows most toxins to act very rapid as they enter the bloodstream of the fish very directly. Any degree of poisoning will weaken the fish, making it vulnerable toward disease.

CO2 levels in excess of 25-30 ppm are dangerous for fish. Common signs for CO2 poisoning are an increasing and more rapid breathing, gasping for air, and a staggering swimming behavior – all leading to suffocation of the fish.

CO2 poisoning can be caused by a malfunction of the CO2 reactor, or the inability of plants to absorb CO2 if the lighting is insufficient.

A quick and long lasting solution is to heavily aerate the tank through surface agitation and air-stones. This will cause the CO2 to dissipate from the water.
 
Thanks a lot guys. I just found a CO2 ppm calculator from somewhere and worked out my CO2 is currently at about 15ppm, which sounds about right. I'm aerating at the moment - with an airstone and a powerhead near the surface moving the water around. Hopefully that should help my fish to stay alive :) Thanks again :good:
 
I would get a CO2 drop checker and some 4dHk solution. That way you will be able to tell at a glance what your CO2 level is.
 
well if you add too much it can kill your fish by gassing them not sure on plants

How would I know if I'm gassing the fish? i.e. what would I be looking to test for?

Thanks!

Ignore every test kit ever invented and look at your fish. Ignore your drop checker, even if it tells you CO2 levels are fine. Forget the on line calculator you used, because it won`t take in to account factors other than CO2 that alter the pH in your tank.

Some fish gulp air at the surface, some act drunk at the bottom, and others try to leap out of the water. It is all basic stuff derived from observing fish and plants.

Judging by your post, and the fact that you are using DIY CO2, I would guess your fish are well and truly safe from being gassed. I would get a drop checker though, as a general guide, but that is all it is.

Dave.
 
hey i just wanted to point out that airline tubing with Co2 going through it will eventualy break down and leak. also ive heard that putting the outlet into your filter can, over time, ruin your filter. check into getting some cheap silicon tubing and maybe a co2 ladder off erbay.
 
Yeah if your fish are gasping your probably killing them. I've got about 8 bubbles a second flowing through my powerhead and a super fine mist of co2 floating around the tank and the fish are fine. Technically the more co2, the more plant growth. My plants have rapidly grown over the last week. I can even tell within a day that they've grown.


I'm using diy co2, and your probably most certainly not hurting the fish. Heck i'd try to bump the co2 up a lil bit if you want your plants to grow faster!!!
 
CO2 levels in excess of 25-30 ppm are dangerous for fish. .

that isnt entirely true, i have run in excess of 35ppm and Tom Barr has measured levels of 45ppm with discus (using a CO2 analyser).

The reason 30ppm i said is because at that level CO2 is high enough to support plant growth, and to stop algae growth. Its best not to go past that point as it comes with experience
 

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