Mass fish loss

[jwaldo]

Hello all!

I have suffered the loss of all but a few of my reef fishes. I have been a reef keeper for nearly 10 years. I currently maintain a 110 gallon mixed sps/lps/soft coral tank.
pH 7.81-8.0 (ca reactor)
spec grav: 1.023
temp: 79-81
ammonia 0
nitrate 0
nitrite 0

There is a Ca reactor, ev240 protein skimmer, kalk reactor, ro/di for top-off.

I have two in-line side tanks of 40 gal each which have a dark and light refugium. Each has 3-5 in of 2-4mm substrate.

I am aware of no foreign substanes or gases in the fish room.

The die off occured within 3 days of a routine maitanence chore of siphoning off the top layer of one of the two refuiums' deep sand bed. I have done this before with no noticable effects. I took less than 1lb of the sand and rinsed for 5-10min in fresh water, then added this small amount to main display. There is no noticible hydrogen sulfide odor. I siphoned some of this sand back out of the main display later and discarded it.

The remaining fish are stressed and pumping their gills.

The corals oddly show no effects.

Did I disturb the deep sand bed too much??

Some of the added sand fell on a palyothoa sp. pylop rock. I know this colony to be somewhat toxic. Could this be the culprit since the fish are selectively affected?

Should I now remove the whole deep sand bed in the side tank??

Any thoughts would be appreciated.

Thank youi

[jwaldo]

I think it is really strange that my skunk cleaner shrimp, all crabs and corals appear fine.

I did a 10% water change, new carbon, mechanical sock filter and cleaned the prot. skimmer.

My next step when i arrive home will be to siphon off all of the sand in the DSB within the side tank, along with another 10% water change.

[Cord]

Could the carbon dioxide from the calc reactor be too high. Check the pH. I don't know if the sand bed would cause this much trouble unless you totally disturbed it. Either way I think water changes and LOTS of carbon are the way to go as a broad treatment for who knows what. Also I would check ammonia. Good luck.

[jwaldo]

Thanks for reply. Ammonia was zero, but i really thought it would be high. I did somewhat of a bone-head thing by removing essentially the whole top 1/2in of substrate in one of the 2 deep sand beds. Still I would expect there to be a smell or at least affect the corals as well as the fish. I continue to worry about the palyothoa sp. rock. Maybe it shoud go just for safety sake.

I am also worried about the CO2. All seems to be going well it. It is a very high quality one (MTC Procal). Bubble rate OK. But you can see that it has brought my pH down over time.

This may end up being a mystery. I'm sure it won't be the first.

Thanks

[Cord]

Carbon should remove palyothoa toxin. If there's too much CO2 your pH should be low. Could the kalk reactor have malfunctioned? I've heard of people's top off systems adding water at the same time that the stirring power head goes on, thus delivering too much kalk.