Nitrates at 0, Fauna load too low
Should I be worrying if my nitrates in my tank are 0? I don't think I have enough fish to keep up nitrate production (unsure if much of the ammonia even makes it to nitrate form if the plants just directly are using ammonia). Last week, the nitrates were at 5ppm, but I had a feeling that they were decreasing over time, and my tank is extremely lightly stocked (11 harlequin rasboras in a 55G relatively heavily planted tank). Should I dose KNO3? Flourish Nitrogen? I ordered some KNO3, but can someone direct me to a reference that can help me calculate how much to add to achieve a certain concentration, and what concentrations I should aim for?
Other possibly relevant info:
-Tank size: 55G
-light is medium (1x T5HO raised 2.25" above tank top, going through acrylic splash guard and glass top)
-No CO2 injection, currently dosing Excel daily. Planning to start two 2L bottles of DIY CO2 in the next 1-2 weeks and run an airstone at night (or not because my filter already has good surface agitation)
-Just started adding recommended dosage of Flourish comprehensive weekly, but will likely stop if I begin dry dosing regimen with dry ferts (NPK and CSM+B)
Plants include: lilaeopsis mauritiana, LOTS of crypt wendtii, argentine swords, jungle vals, ludwigia repens, green cabomba, anubias nana, anacharis, and a small tuft of micro sag i think.
Any tips would be appreciated! Thanks!