Hi xavi_pr
I think Ajm200's observations are correct. Ammonium Nitrate in large quantities will bother your fish
🙁 , but it will bother you as well
. Too much Ammonia in a tank with enough light is a surefire way to induce algae.
A plant is a plant whether it is grown submerged or not and their needs are pretty similar. They both need NP & K and Trace Elements.
I believe I read somewhere round here that Tropica's TPN+ contains Ammonium Nitrate, but this is purely for commercial reasons (it's cheaper than the alternatives).
You can buy your liquid ferts from one of our sponsors. TPN+ is an all in one solution that contains NPK & Trace, although it is an expensive option if you have a large tank.
Alternatively, you can buy the dry salts from one of our sponsors and mix your own for a fraction of the cost.
You will need KNO3, KH2PO4, MgSO4 and Chelated Trace Elements. Some of these can be purchased from some garden centres in the form of dry salts.
There was a thread about this very subject somewhere on here before.
Might be worth having a search for it.