Approaching total coral wipe-out

[asylumdown]

Actually yes. I have my own theories about cyanobacteria but my experience with it is that once it's given the opportunity to proliferate it's very tenacious. It took advantage of an opportunity and became a threat in its own right, even though I seem to have corrected whatever it was that started this in the first place (I think it was biopellets, but who's to say really)

I left the chemi-clean in the water a day longer than recommended before doing the water change and I'm letting my skimmer do what is essentially another slow motion water change right now, but even in just three days of the the 'drugs' working their magic, corals that were continuing to decline under advancing sheets of cyano seem to be forming hard lines in the spots where the tissue had been dying. That's generally the precursor to new growth plates IME, so I'm optimistic.

Whether this will have long term effects on stability in other areas I can't say, but as a short term solution it seems to have helped

[brotherd]

I remember you battling cyano a while ago. Do you run a refugium? I'm wondering if the Chemiclean dose would be more effective if it was spread out over the major chambers of the system rather than dosing all of it into just the display or sump? Your situation is very unnerving.

[asylumdown]

yah that was in November. I've wondered if something 'broke' in the bacterial chain of my tank when I did that that somehow lead to all of this 4 months later, but I have had a hard time convincing myself of that. Namely, after I did the chemi-clean dose in November, the tank was pristine for 3 months. The coral colours were banging, I sold TONS of frags, things were growing like crazy. The only problem I was having was with my BP reactor clogging after I started dosing with MB7, something that had never been an issue for almost 2 years prior.

The onset of things falling apart when they did was incredibly sudden. It was literally like someone had poured a cup of poison in the tank one day. It also coincided within a matter of days of me re-setting and modifying my pellet reactor, and changing brands on a bunch of products. I've now talked to a bunch of people who are using the same products I have with zero issues, and what happened to my tank follows the general description of what people who've OD'd on organic carbon have seen.

I'll always be more inclined to think it was the obvious, temporally linked event rather than some unknown, slow acting time bomb whose fuse was lit months before but left no evidence until all of a sudden everything coincidentally just fell apart the same week I flooded the tank with an unprecedented amount of carbon polymers, species of which have been shown to be toxic to SPS corals in high concentrations. However, I'll never really know. I changed too many things too quickly and wasn't (/couldn't) test all the relevant parameters that could have been affecting things.

In any case, as of today, the corals are growing again and the cyano is gone. Whether that's a permanent thing or false ray of hope I'll figure out in the coming weeks.

[Seriak]

So are you still using pellets?

[asylumdown]

yes, but I'm looking in to replacements. I don't think it's pellets that are the problem per se, but how they get used and how little their mode of action is understood. There are definite red flags about them - first and foremost of which being that no one has even the slightest clue about how much of the polymer makes it in to the water column, or even where the majority of the nitrate reducing activity is taking place (in the reactor, or in the tank using the carbon that dissolves/breaks off the pellets?). The fact that people report it takes weeks to see a reduction in nitrates has always made me suspicious - I've run the reactor at a slow tumble with not a lot of water pass through, and the bacterial mats that form inside of them grow lightning quick. The entire column of pellets can be fused in a thick, white, microbial mass in as little as 48 hours. Alternatively, when the pellets are tumbling fast enough to prevent clumping, there is usually zero build up of bacterial mulm anywhere in the reactor. Also, it's not uncommon for people to add pellets to their system and within days see the entire tank turn in to a lush cyano garden. I've always wondered if that means that the bulk of the 'work' pellets do is actually taking place inside the water column using carbon that's sloughed off, but you'd need to do some really sophisticated organic carbon analysis (that to my knowledge no one has ever done) to know for sure.

If I could find a nitrate control method that made sense with my setup that was not pellets I'd switch, but my tank is too heavily fed to not have some sort of intentional nitrate control system in place. Adding a gigantic refugium or remote DSB is physically not an option and I don't really have any space for something huge and bulky like a sulphur denitrator or an ATS. The only other 'proven' method is liquid carbon dosing, which is basically the same thing with a different delivery method but I don't know I'm ready to commit to switching. Dosing it in liquid form has the benefit of giving you precise and immediate control over how much carbon you're adding, but at the end of the day no one really understands the full spectrum biochemistry of carbon dosing anyway. I might end up switching to vinegar or vodka/vinegar dosing at some point.

In the meantime, I'm running my modified reactor with 10% the pellets it used to have before I increased the effluent pipe diameter, and I've restricted the flow through it significantly. I'm also monitoring my nitrates and will only add small amounts of pellets if the nitrates continue to climb over a period of weeks. This seems to be a safe level, but then again maybe pellets had nothing at to do with the what happened in the first place.