I think 3 wpg on a 20 gallon is moderate lighting.
You can get the same results from DIY (fermentation) CO2 as you can with pressurized, but it takes more work and near-constant watching. I have had DIY since I started and have finally found a way to keep a similar amount or CO2 going at a fair consistency, but I have to change out the mixture weekly and output varies with the house temp. If you have the extra money to plunk down on a pressurized system, I'd say do it. If not, you can still have a wonderful planted tank with DIY.
The "difficult" plants are difficult in regards to water quality and being finicky about proper fertilizer ratios. The source of CO2 shouldn't matter as long as you have enough.
-Dave
You can get the same results from DIY (fermentation) CO2 as you can with pressurized, but it takes more work and near-constant watching. I have had DIY since I started and have finally found a way to keep a similar amount or CO2 going at a fair consistency, but I have to change out the mixture weekly and output varies with the house temp. If you have the extra money to plunk down on a pressurized system, I'd say do it. If not, you can still have a wonderful planted tank with DIY.
The "difficult" plants are difficult in regards to water quality and being finicky about proper fertilizer ratios. The source of CO2 shouldn't matter as long as you have enough.
-Dave