Mysterious coral losses - at my wits end.

[asylumdown]

Just to clarify, that isn't exactly right. pH changes (lowering pH) alone convert ammonia to ammonium. Prime does somethign else which is independent of pH, and does reduce the toxicity so you need not worry about it.

Thanks Randy. I'll have to trust whatever prime is doing.

Here are just a couple of overall thoughts based on the info you posted:

The FTS you posted on your blog wouldn't leave me to believe that your tank is massively overcrowded with fish, presuming that you've a highly functional skimmer.

oh man looking at those pictures makes my heart hurt. It does not look like that anymore. Those pictures are a little deceptive for two reasons. The first is that my tank is 3 feet wide and open on two sides, so those rocks are both all in the middle of the tank, and the fish at the back look much smaller than they are. That Richmond's wrasse is 7" long. I also have quite a few fish that spend most of their time in the rocks. You can't see 17 of my fish in that first full tank shot, including most of my largest. The second is that while I haven't added anything new, everyone has grown since then. That's practically a baby photo of my cowfish. He's pushing 11" from head to tail now. I do have a good skimmer though, a Deltec SC2560.

Dosing much of anything into a reef system other than basic ionic chemicals like calcium, carbonate and magnesium is exceedingly perilous. That's particularly true with additives where you really don't know what's in them (such as MB7).

Ditto for items where you might know what's in them, but really can't control the dosage, such as bio pellets. Randy would have to comment on this in his case, but this is precisely why I choose vinegar for nitrate control rather than biopellets.

At this point, I completely agree.

My thought on Chemiclean is "never, ever" in a reef system. Same for anything that contains antibiotics, as you really don't know for sure what you're going to be killing.

The product makes me uncomfortable, but in both cases the cyano was so bad it was directly killing corals. I could spend 3 hours siphoning it out (which seemed to spread it around more than anything), and by 3pm the next day it would not only be like nothing had happened, but worse. I've gotten away with using it in the past, so it was a risk assessment over what was acutely worse at the time. The real problem of course, was what was driving the cyano in the first place, which was almost certainly the pellets. I was just so afraid to mess with something that had worked relatively problem free for so long. I thought I could outsmart mother nature by forcing it to do what I wanted, hence the chemiclean and MB7.

Lesson #1 - when a system you have built ceases to provide the result you intended, change the system. Don't throw gasoline on the problems it's creating

Your ammonia issue was likely very transient. In a functioning reef tank with ample live rock and a substantial sandbed, there's a huge amount of ammonia-processing potential. If it were me, I wouldn't continue to dose Amquel, Prime, or any other "ammonia binder".

I hope so. This morning the colour of my ammonia test looks like it's between 0 and 0.25ppm, so it's risen since last night. I did another water change and dosed a conservative amount of prime, which seems to have brought it back down to unreadable. I'm not going to add prime willy nilly, but I will keep adding it responsively to test results until the levels stop increasing.

If it were my tank: I would immediately take the biopellet reactor out of the system (completely),

Done. The reactor is sitting in my sink waiting until I have time to clean and disassemble it. Then it's moving to a shelf in my garage.

leave the GFO off-line, continue to use GAC that's changed out once a week until your tank stabilizes, and probably execute 4 or 5 20% water changes every other day until your coral necrosis reverses. During this period, the only thing I would dose into the tank is calcium, alkalinity, and magnesium. I would also consider putting the tank on a controller, if you don't already have one, to ensure that you're not getting fooled by something like intermittent power outages overnight, or temperature swings well outside the safe limits.

Yes to all of this except the GFO. The first time this happened was right after I switched GFO brands so for a while I thought it had something to do with it, but this time corals started dying after I hadn't run any for weeks. They've died with it, they've died without it. Putting it back online might have been a knee jerk reaction but I've been messing with it too much already and it's running now so I'm going to leave it alone. I've stopped dosing my major ions since consumption rates are all over the place and am going back to controlling them with large daily water changes like I did last time. Alk falling faster than water changes could replace it was a good indicator last time that things were turning around.

Thanks for all the advice guys.

 

[dkeller_nc]

My thought about removing everything from the system other than GAC is the "Back to basics" idea. Many aspects of the "bleeding edge" maintenance of coral reef aquariums are relatively uncertain and/or take a good deal of monitoring and a practiced eye to use effectively, such as using biopellets, trace element additives, amino acid additions, etc...

But, I think most long-time reefers would agree that the basics of flow, lighting, and water changes are pretty bullet-proof, they just take a lot of work (at least the water changes do).

The reason I suggest removing the GFO is that depending on how much is being used in the system and how long its been in use, one can easily drive the phosphate levels down so low that it harms the corals. However, the converse isn't necessarily true - you might want to read Richard Ross' thread "Guess the Phosphate Level" in the SPS-keepers section. The downside to a relatively high phosphate level is the possibility of having difficulty with controlling nuisance algae growth.

You might consider setting up another large tank as a FOWLR, however, and removing the largest fish to that tank. The max size of the yellow spotted cowfish is about 18" according to Live Aquaria, so this may be a necessary change irrespective of the coral health in the tank. That's assuming that you regard your larger fish as pets and wouldn't wish to give them to a fellow hobbyist. Another thought would be to set up a smaller tank and move the corals and some of the smaller fish to that one. Your current tank then becomes a FOWLR, and you'll have an easier time controlling the smaller tank's parameters.