Love itPotassium nitrate as recently shown to be safe to use in reef tanks. As for an algae bloom that is highly dependent on a number of other factors like excess PO4, flow, lighting, CO2 and O2 levels, grazers, export methods.
I have used it to boost my NO3 to 10ppm in a day with zero ill effects. I also keep PO4 very low (.01-.03) and have a large chaeto fuge and lots of grazers, large skimmer, Carbon dosing.........
You told me to try nitrate at 10 and phophate 0.03 i did achieve it and color are awsome
Growth is normal but color is better in my reef with nitrate and phosphate in it
But as other says it’s not cause our test say 0 that you have 0
If your sps are pale your tank coral will tell you they are starving