What's your water like?

If I use water from my well I get stinky brownness (smells like a wet dog) in less than 24 hours. But my rez temps are in the 80's.

Switched to distilled + calmag, problem solved.

I've even used chlorine bleach in the rez (1-2 ppm) despite some "experts" telling me that'd kill my plant. (Scorched her a bit, I'll confess, but I killed the brown slime and the plant survived). A more conventional approach is administration of 3% H202 at 5-15 ml per gallon, at 3-day intervals.

But if you are inoculating a warm nutrient solution with bacteria/fungus (with no natural controls like beneficial organisms) from your water, rapid slime growth is very possible.