The nitrogen solution is comprised of potassium nitrate which your test kit can read and other compound is urea which is more similar to ammonia which your nit. test can’t read, that’s what their talking about when they say double it. It’s giving you a rough estimate of total nitrogen available in tank.
Anyway as I see this is what went down. You started dosing Fluorish which has no nitrate/phosphate, your source of those two compounds was feeding/fish waste, your plants had all they needed, the complete food group plants need for a while but now the minimal amounts of nit/phos waste provided is now depleted and just feeding your fish can’t keep up with plants needs. So without those major macro nutrients your plants have stalled and algae is getting upper hand.
Cut fluorish down to .4ml a week which is dose for the actual 5gal water your tank contains, the smaller the tank the more important it is to dose on actual volume of water contained in tank. Then target getting phos up to around 1’’ish ppm and nitrate at this point shoot for 8ppm, no more than 10 and figure out a dosing scheme to keep them there.
Your parva melted so it’s uptake is focused on pulling nutrients from substrate, unless it main stem has died it will be back in about a month, it’s what they do. MH is probably transitioning to submerged form so hopefully it will be back but right now it not uptaking any nutrient from water column either. Watch your rotala it will be quickest to respond to getting a balance in ferts in water. Don’t change your lighting, make these nutrient changes and observe tank and monitor levels every few days. Keep dosing on a even keel and see what result is. If you go changing a bunch of things you don’t no which one fixed problem.
Also what substrate, how deep is it and what filtration are you using? Also how much and how often are you changing water? How are you prepping water before change? RO or tap?