P always rising; N always undetectable

[Clavius78]

My 12 year old 600ltr mixed reef is doing OK, but only just OK. Coloration in LPS is great. It's just good enough in SPS. The only issue I have with the tank that my phosphate is always on the rise, whilst my N is always below detectable. And I can't figure out why that is.

I run a Mini Bubble King 200. And an algae reactor that gets good growth, but only if I constantly add nitrates manually, so the algae can consume the excess P and the artificially added N. If I don't do that, there's no N and the algae dies.

So, I have an imbalance that I correct almost daily. I need to understand why this imbalance keeps returning. I feed frozen mysis and artemia daily. And sometimes switch that around with dry food and algae leaves for my surgeons. I assume these all have N and P in normal naturally balanced levels.

What else can it be? Stored in my rocks? How can I check that? Do I just need to keep balancing this out until all P reserves are gone?

 

[Vinny Kreyling]

The only way I know of to check if it's the rock is to place a piece in fresh salt water& let it sit a day then test. The rock should leach some into the water, if that is indeed the problem. All food will introduce phosphate into the water & not necessarily in the right proportions.

 

[Michael Hoaster]

When conditions for a reef tank are good, they're bad for algae filters. With your particular situation, it sounds like you should take the algae filter offline (or greatly reduce its photoperiod), and use a phosphate absorbing media instead.