I'm going shock you, so hold on to your test tubes!
180 gallons total water volume, 125 gallon DT.
I'm running, successfully I should say, N03 at 30ppm to 50ppm. WHAT? Can't be right, right? No, it's correct!
Yes, for nearly a year. I have unsuccessfully tried carbon dosing, HUGE water changes, bio pellets.....etc with no avail. ( Yes, all done absolutely correctly, to be honest, little reductions where had, but none reducing to 5-10)
With that said, I do and have ran a refugium with chaetomorpha for months successfully, pulling a gallon or so out a month. Nice green and healthy.
I do run my DKH high at 10.5 and calcium around 500. Mag around 1400. Kalkwasser in my ATO reservoir top off. Tons of flow and PAR at 300 at the tops off my aquascape.
The other value that will "SHOCK" you is P04. It's at 0.12! WHAT? it's correct!
No pest algaes, DT is free and clear of them.
All my SPS are growing, healthy and colorful. LPS is nuts in growth and color. I have to frag soon!
Water changes are 10 gallons a week with regular Instant Ocean. No dosing anything except alkalinity once in a blue moon and kalkwasser.
Skimmer and occasionally a filter sock.
So, yes you can have a healthy, thriving, colorful reef with insanely high nutrients, but it needs export and needs to be done in a mature reef (12+ months old) over time.