In article ,
says...
I have a 55 gallon plant tank. I am just curious about what others use for
water. By that I mean.....

The water in my community is very high in Phosphate. NOT a good thing. But,
I have an RO DI system (I also have a reef, which is why I have it). While
it makes wonderfully pure water, it takes out the good stuff plants need.
So.......


There is a formula, corrected from an earlier post, using baking soda, potassium
chloride, calcium carbonate, and epsom salt ... at the krib. See the article
penned by Roger Miller he

http://www.thekrib.com/Plants/Fertilizer/dosing.html

In that same thread there are several other good articles that discuss how to
measure these household chemicals, what concentrations to expect when using these
amounts, etc. Additional components are needed for growing plants. I think that
PMDD would supply them all.