Low Light , E.I and CO2


Junior Poster
Oct 21, 2008
Hello friends

I have been using EI for sometime and have got excellent results.Thank you Tom once again for giving us E.I.

I am planning to start a new planted tank but with Low light(since tank water temp goes to 32C in summer). I will be using ADA aquasoil as substrate and pressurized CO2 .

In this forum I got Gregs advice on EI with low light.

"The Estimative Index method works best for a high light and well planted aquarium. However it is not limited to higher light setups, smaller quantities of fertilizers can be dosed if low light is used. Also, the frequency may be reduced to 1-2x a week at low light(1.5-2w/gal). "

Can someone please tell me the CO2 level to be maintained for LOW LIGHT setup using E.I.

Since CO2 issues are behind 95% algae problems I am not sure if lowering CO2 will not invite algae.

Hope to hear from experienced members.




Guru Class Expert
Jun 8, 2007
You should maintain the same co2 level of 20-30ppm or so. The difference is that if something does go wrong and co2 levels drop, algae will not set in nearly as quickly in a low light setup. Also since demand is less under low light, it may take less co2 to maintain that level. But you do not reduce co2 concentrations under low light, you either use it or you don't. A low light/EI/CO2 setup is a very nice one to have, I had one for quite a while. You get nice growth, few algae problems, and not quite as much maintenance as a high light setup, so it's a good tradeoff.


Guru Class Expert
Jul 3, 2007
also you should have a leaner dosing schedule with a low light tank. not as much nutrient consumption is necessary when doing low light even with co2. light is one of the limiting factors of how much your plants grow. lower light=low nutrient consumption. as greg mentioned