No not nitrates, I'm talking total dissolved solids, TDS... the total TDS is under 150 PPM in all my tanks all the time. If it gets over that, I change my water.... Unless it's my discus tank, and they get a large water change 1-2 times per week regardless of the TDS.
I think the filter is 90 gal rated, could be wrong, but either way... it's rated at more than the tank and the Mag 250 is just icing on the cake.
The fluvals always seemed to go through more seals and need more maitenance for me, they just weren't as "user friendly" as I like and I had to replace 3 of them in the amount of time I had 1 of the Magnum 350 Canistar filters (not the H.O.T variety).
I didn't feed the discus at all yesterday, this morning they ate an entire Wattley's cube!! WOOT!