Live Rock fuzzy coated minimal coralline

Hairmetal89 · Apr 10, 2019

Been struggling since rebuild 2 yrs ago keeping live rock clean in my SPS tank. Always a coating of brown fuzz. I can never get coralline to dominate rock surfaces like all the great sps reefs in this forum. I run opposing MP40s at 75% in my 120 gallon tank. Flow wouldn’t seem to be culprit. When I test for Phos and Nitrate w Salifert they come back 0. I run 3 drops of nopox daily. Had issue before dosing nopox also. Dose 2 part. 420 calcium 8 Alk. My sps grow but colors are just okay. I know there’s no simple answer here but is there an obvious “You likely need to fix this” from an expert?

Tait · Apr 11, 2019

I'm new to the forum, but have seen this happen with rock that's been in tanks for a very long time. Granted some systems have been running for decades without issue, but they were probably started with fresh rock and haven't gone through many nitrate spikes. For most tanks though spikes happen, so over the years the rock absorbs nitrates and phosphates. If you purchased it from an LFS it could be just resold from any old tank. I worked at an LFS, sometimes people would trade in LR that had just come out of a crashed tank, or an overfed fowlr. Hopefully most stores dont do this but they would take in the old rock, scrape any algae, then put it in a tank and sell it. A lot of customers would have hair algae problems. Because of this, I would only try to sell south seas base rock. So even if nitrates are low in the water, there could be a lot absorbed in the rocks, add to that lighting to sustain SPS, and you could have a fertilized garden for hair algae.

Hairmetal89 · Apr 11, 2019

Tait-
Very interesting take. I appreciate the detailed explanation. The theory makes sense. My rock was from my own FOWLR tank I’ve had for 10 years or so. When I broke my tank down for this sps reboot I took that rock and bleached it for a month in a tub to rid of any hair algae in an effort to “start fresh”. I guess I’m sorta stuck now with this rock cause all my sps are encrusted. Maybe I try a fluconazole treatment(?). The whole optimal nutrient in/out equation has eluded me. The fuzz on my rocks suggest I have too much nutrients despite 0 on salifert for n and p. But my sps seem dull. So feed more? Add aminos? To help sps and risk making rock worse? Scratching my head... thanks again.

Dkeller_nc · Apr 11, 2019

It's possible that you've rock that has a good deal of precipitated calcium phosphate from your old tank. Because there's phosphate available to it, the algae grows on the rocks. And because you've colonies of continuously growing algae, your water consistently tests "0" for Nitrate, though it's unlikely that it's truly testing "0" for phosphate - you'd need a Hanna Checker ULR to test to the ppb levels.

In any event, you likely want to kill the algae, which will allow any calcium phosphate on the surface of the rock to gradually leach back into the tank water. That has the advantage of both (potentially) nourishing your corals and removing the reservoir of adsorbed calcium phosphate on the rocks.

There are several ways to accomplish this; ones to get critters that will eat the algae. In a 120 gallon tank, that's probably fish, and probably the various foxface species. Urchins are another option. A slightly more drastic method would be flucanozole treatment.

BTW, with "0" nitrate and phosphate, I wouldn't personally dose NoPOX, or any other form of carbon dosing for a while.

Hairmetal89 · Apr 11, 2019

Dkeller- Thanks for this insight. Actually makes good sense to me. I should probably grab that Hanna ULR ... my Salifert always give me "clear" or 0... and I shake my head at it. I'll likely go the fluco route, I have a yellow tang and my experiences are adding a foxface (while a great fish) would be war. Never had an urchin although some of the tight spots between corals he'd have a hard time getting to. Again, thanks for the time you took to share some thoughts, very helpful.

Tait · Apr 13, 2019

Yeah I would think the bleach would have gotten rid of most of the nitrates or phosphates, so I dont really have any clue whats causing it.

Dkeller_nc · Apr 13, 2019

Well, bleach won't remove precipitated inorganic phosphate. It's an oxidizer, and the phosphorus is already oxidized into phosphate. What bleach will do is oxidize any organics, like dead algae, dead critters, etc... For folks that are trying to "nuke" existing rock that's been in another tank, a common procedure is to remove any organics with a bleach soak, followed by a rinse, followed by an acid wash to remove precipitated inorganic phosphate.