[asylumdown]

After my massive renovation related coral losses, I've been doing everything I can to get the tank back on track. Part and parcel of that has been to amp up the GFO use as, much to my dismay, the pump that drove my reactor died sometime while my house was being renovated in August. For at least a month, the tank had no GFO, in addition to no water changes.

While my corals were dying like it was the hottest new trend of 2014, the one problem my tank had absolutely none of was cyano. As some of you may remember from earlier posts of mine, I've been struggling with cyano for a while now, as it always seems to capitalize on dying coral and smothers the newly dead skeleton - sometimes within hours of the RTN event.

So anyway - I replumbed the the return pump assembly of my tank and replaced my external reeflo with one mother of an internal, quieter, more energy efficient pump and built a manifold off that line to run a new reactor that sits next to the sump where the old pump used to be. It took 3 days cuz I'm no plumber, but voila, no more making a giant wet mess every time I want to change the media, and no more bulky reactor and pump in my sump. I add a fresh batch of incredibly well rinsed Rowa phos and BOOM! Next day cyano shows up pretty much everywhere.

I kid you not - ZERO cyano in the tank the day before, even on coral skeleton that had been dead long enough to turn green and start to grow coraline. Day after adding GFO back to the system - traces of cyano on everything. Fast forward to today, and even with 400% cumulative total water change, insane attention to parameters, the removal of about 60% of the dead, exposed corals skeletons, and the cyano problem continues to worsen daily.

I have now read far too much literature on "black reefs - large swaths of pristine reefs that are smothered and die under a thick blanket of cyano bacteria - happening within months or years of iron hulled ships wrecking and sinking on them, to not be suspicious of the F in GFO as a possible driving culprit of cyano bacteria. The most recent research on black reefs seems to confirm that it is the sudden availability of excess iron from the rusting hulls that drives these systems towards cyanobacterial dominance. To make an even more convincing case, some very crazy (smart?) people have been suggesting dumping huge amounts of iron in to the open ocean specifically to cause massive algae blooms for carbon sequestration for a couple of years now.

When people get cyano, the standard wisdom is to ramp up your GFO use because clearly you must have a phosphate issue. But I can't count the number of threads I've seen where people do exactly that and their problem gets no better or just gets worse. I've also been able to find a bunch of threads around the internet where people have noted cyano appearing immediately after first additions of GFO. Suggestions are usually that somehow the cyano is now being favoured by a reduced nutrient environment, but almost never does anyone suggest that the significant amounts of iron hydroxide dust that gets dumped in to a tank with every GFO change might actually be as vital a nutrient to cyano (which uses a relatively large number of iron atoms in their photosynthetic structures compared to other autotrophs) as N, P and C.

I never had so much as a trace of cyano when I was using PO4x4, which encapsulates the GFO in some sort of polymer bead. Literally the first time I saw cyano in my tank was the same window of time that I stopped using that expensive and hard to get product and switched to a granulated, dust producing form. I've battled it ever since.

That was a long rant (but hey, I write long rants sometimes), but I'm now very seriously looking in to non-iron based phosphate adsorbers and if I can get over my fear of aluminum in a reef tank, I'll probably switch to see if it helps.

Does anyone know of other kinds of phosphate binders that can be used in a reef tank that aren't iron or aluminum based? Has anyone ever figured out how to use lanthanum chloride as a safe, routine (as in dosed in a daily and automated fashion) phosphate control method in a reef tank?