I have been using Scotts Liquid Turf Builder in my planted tank along
with Flourish and Flourish Iron. What I found was that too much of it
caused the ammonium and nitrite to spike. The bio-filters took a while
to convert that toxin into nitrate. But I was amazed at how fast the
nitrate was absorbed as soon as they were produced. The plants did
very grow rapidly as a result of the fertilizer. Also, my brownish
slime problem seemed to have cleared up. Incidentally, anyone know
what is the brownish slime?

Despite the spike in ammonium and nitrite for days, I had no fish
death. In fact, I didn't see any significant indication that the fish
were stressed. In fact I had several live bearer births during that
period with many survivors. That was actually very surprising.

Anyway, lawn fertilizer in the planted tank was probably a bad idea.
I'll probably use the rest of that bottle of lawn fertilizer on my lawn
.....