The Planted Tank Forum banner

Not enough Co2 without being too acidic!

1914 Views 13 Replies 9 Participants Last post by  HD Blazingwolf
This is, I'll bet, a pretty dumb question for those knowledgeable. I've been keeping aquatic plants for years, but have recently taken things full-bore and built a new stand with canopy that has big light output going in cycles (I have morning/ noon/ evening and lunar cycles), and I purchased a C02 injection kit.

The tank is just cycling in right now (75 gallon) and I have some bulbs planted and some mature onion plants (I used a Flourite base, split the tank 1/2 sand 1/2 gravel).

My issue is that with the Co2 injection, I have a PH of 7.2 (I keep catfish and don't want to go acidic) and a Kh of 3. So from what I'm seeing that means my tanks capacity for Co2 is something like 9ppm, and I need this to be more like 23ppm.

What do you do with this? I can't raise the hardness (and that sounds bad for the fish) and the PH is already kinda high for tropicals it seems (don't they prefer more alkalinity?).

I'm totally new to the boards, I've looked allot online, but its difficult to find info that answers this question. What can I do to achieve a Co2 level optimum for plants AND maintain a hardness/ acidity that's optimal for fish??

Thanks in advance!
1 - 1 of 1 Posts

· Registered
5,367 Posts
Your pH will be normal in the morning and drop during the day as gas is added, all the fish I have ever had are fine with the pH drop and only bothered by being gassed to death. My kH is much lower than yours and I have never had any problem with the so called limited buffering capacity that I know of, if I were you or me just try to get a good amount of C02 in the tank by watching the plant health and growth along with the reation of the fish. You can test pH and kH and have a drop checker and never really know the amount of gas in the water but these methods can be guides to making adjustment in gas amounts but are rarely spot on acurate. You don't want to add so much C02 that your pH drops so low that your nitrifying bacteria slows to a point little activity and by adding oxygen to the water column with air stones/wands during the lights/C02 off period you can help build a larger base of nitrifying bateria which will help the tank as a whole perform better, so example lights/C02 on 8 hours, air on 16 hours, can equal good things, good luck.

Don't forget about circulation to distribute C02, nutients, etc. equally around the tank.
1 - 1 of 1 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.