Hey everyone, I'm running a 20g low-tech tank (DIY CO2, weekly Nutrafin GRO fertilizer, 2x13W CFL bulbs). I'm growing plants that are reputed to be rather hardy (red & green crypts, wisteria, hygrophila siamnesis). Would it be in my best interest to purchase another light for my tank, which would bring me up to 52W of CFL light on the tank (2.5W/g rather than 1.25)? I can do so rather cheaply and I want the plants to look...green and healthy not brown and shriveled. Thoughts?
How are the plants doing so far since you said you're keeping plants that are "reputed to be rather hardy"?
You can do an upgrade but once you past the 2wpg threshold, be prepare to move to high tech. With 1.25 wpg (not t5s though) you probably won't benefit too much from CO2 injection, water surface aggitation should be sufficient and CO2 and waste released by tank inhabitants like fish.
Getting to 2.5 wpg CF will probably require, like bsmith mentioned, a more steady constant supply of CO2. Algae is partially caused by insufficient or inconsistant CO2. Also, you'll need the additions of ferts to help the plants to outcompete algae.
So think carefully before stepping up. It is one of those things that, if you do halfass, you're going to regret it in the long run. It'll probably make this even break this hobby for you if you don't watch out. It'll make this hobby a chore instead of a joy.
You can try to maintain your DIY CO2, but be prepare to either cut the lights back down or go pressurized with ferts, not to mention the numerous other doodads.
Btw, just because you have high lights doesn't mean you'll get green healthy plants. There's more to it. And just because you have lower light doesn't mean you can't get green healthy plants, you just have to choose which plants. Low tech tanks can be gorgeous as well, as much as you want it to be.