Fertilizer Question????


Junior Poster
Apr 26, 2009
If you do not have any CO2 in your tank and have low light slow growing plants such as Anubius, can you still add dry fertilizers to the tank water. My tank is 100 gallon and also have a 80 gallon and 30 gallon. If this "can" be done, would you cut the PMDD quantity in 1/2 or 1/4 quantities, or would algae become an issue. Any help would be appreciated.
thanks in advance.......

Tom Barr

Staff member
Jan 23, 2005
you do not get algae or many issues for adding ferts, they can indirectly affect uptake of CO2 (generally increasing it), and when that occurs then all hell breaks loose with algae. going from high or moderate CO2, to low/very limiting levels, or stable levels to non stable levels seems to cause the most issues, in CO2 and non CO2 enriched systems.

Historically, many have blamed nutrients, however, simple test that falsify such claims show there's obviously some other mechanism causing algae other than nutrients.

CO2 moves around quickly, and algae appear to response well to it.
Where it's stable, then the plants adapt and do pretty well.

Tom barr


Junior Poster
Mar 7, 2007
I have a terrarium with an aquatic bottom that I don't add any thing to and my anubias and swards grow well. The lighting is very low and on the upper level I grow terrestrial plants, it is inhabited with tree frogs. I do however mist the tank with old water fro my high tech aquarium which I think add just the right amount of ferts so as not to increase co2 demand but feed the plants just a little.