five.five-six
Well-known member
Maybe that rats nest under your tank is rusting? Check your impellers and magnets for rust. Does your alk fluctuate? Personally I don't think you have a nutrient issue. Tanks run fine at those n03 and po4 numbers.
No iron spikes so it's not rust and copper is in check so not wiring.
I test alk weekly and it does run a little high but have brought it down lately.