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CO2 Levels Without Fish

709 Views 2 Replies 3 Participants Last post by  evanluke
I accidentally killed off all of the fauna in a tank last night, lost all of my breeding danios, some new otos that were doing quite well, and a bunch of snails and shrimp. I was ramping up my CO2 but fell asleep before I had it dialed in. :( Totally my fault, and I know what I did wrong, but it got me thinking:

What CO2 level could/should be run in a tank without animals?

In my specific case, this tank is a new "moss scape" that has just started to really grow (mostly Singapore and a little Java). I have some vals and hair grass as well, but the moss is supposed to eventually cover about 80% of the tank. How high could I keep my CO2 if I never add animals to this tank again? Would overdriving the CO2 accelerate moss growth, or would a system balanced out with fauna see better growth? I auto dose ferts daily and have modular CFL lighting that I can up/down as needed (sky's the limit). I just can't figure out the right words to Google, lol.

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· Administrator
12,199 Posts
Sorry to hear about your loss.

Without any flora, you can run the CO2 much higher than normal, and this means you can drive the plants harder (with more light). Of course, as long as you are providing sufficient fertilization, algal problems will be avoided.

Of course, there comes a point where injecting more CO2 will just become wasteful.

I would try to start around 45 ppm of CO2 and go from there. However, if you only have mosses, the increase in CO2, while theoretically will increase their growth, in actuality, you may not see any noticeable difference.

· Registered
37 Posts
Super bummer! I've done it a couple different times so I know how you feel.

I prefer not to increase CO2 levels dramatically without fauna.

For me it breeds bad habits and once CO2 levels get high enough, they can affect oxygen levels (via pH) and plants will not do well either.

The one use case where I might do it is with a dry start tank to encourage a smooth transition of an emersed grown carpet.
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