High Nitrates Help!

[JurisHP]

In my last thread, I posted that I lost all of my fish in the span of about 4 days (180g tank running for 13 years)....I have one Yellow Tang left. Over the past few weeks, I have changed 100% of my water with RODI (fresh filters), have vacuumed my sump of all detritus (also cleaned the gravel really well with my siphon while changing water), started dosing NoPox, have put no food into the tank, and my nitrates won't budge.

I have a huge protein skimmer that is skimming normally.

I don't know what else to do....is it possible that all of my rock needs to be replaced?

 

[blaxsun]

Without knowing what your nitrates are (were), or details on your tank (mixed reef, cleaning crew, filtration system, etc.) it's hard to speculate. From my own experience, though - you shouldn't need to do 100% water changes - and you definitely don't want to replace the rock (this is helping).

 

[Twoddler]

Cleaning gravel really well in an established tank = Hydrogen sulfide, but just speculating

 

[ScottB]

I have to suspect your nitrate test kit is bad. Unlike PO4, nitrate does not bind to aragonite. If you did a 100% water change all in one go, you would have virtually no nitrate.

What is your phosphate level?
What is your nitrate level?

 

[JurisHP]

Nitrates were tested with 2 separate kits (Red Sea and Hanna)...both read over 75.

It's a mixed reef...mostly soft corals....one fish left.

Agreed that the 100% water change should have solved my Nitrate issue, but it didn't.

Phosphates are a little high...no Ammonia or Nitrites.

Really a head-scratcher.