Corals Not Opening and Dying
 

Two years ago the Arctica Chiller quit working and the temp in my Red Sea Max 250 went to 94 degrees. All the corals and all but two of the fish died. Since then we have had only rock and two fish. I found copepods a month ago. We went to a reputable fish store and bought five corals. Corals were zoanthids, green star polyp and a kenya tree. None of them have opened. They look like little white bubbles and the kenya tree went to mucus and is gone. They were under LED's in the store. We converted the tank to LED's at 50% before we bought the corals. The lights stay on 12 hours and ramp up in the morning and down in the evening with blue moonlights at night. The corals were bagged and dripped and placed mid tank on the rocks. Water parameters are as follows:
pH is 8.4; Ammonia is 0; Nitrite is 0; Nitrate is 0; Phosphate is 0; Alkalinity is 1.72, Calcium is 1.03 and salt is 1.023. We had only soft corals in the tank before the crash. We do water changes every 5 to 6 weeks. The rocks have brown diatom algae on them.
Any idea what could be causing the corals to not open and die? Do we need to break the tank down completely, replace the sand and the rock and start over?

Are you saying Alkalinity is 1.72 dkh and Calcium is 1.03 ppm?

Also, 12-hours of light seems too much to me.

Yes, on the Alkalinity and the Calcium. We just installed the LED system into the hood of the Red Sea. Very easy. Suggested total on time for ramp up and daylight and ramp down was 12 hours. We started at 36% and increased to 50% thinking they weren't getting enough light. The only other thing I can think of is that when the corals died, so did the infestation of red planaria. I would think the water changes would have taken care of any poison, especially over a two year period. Ideas??? Suggestions???

I think those are low...
Maybe someone else can confirm.
But I think Alk shoukd be around 8-12dkh depending on who u ask and what u are keeping....
And Calcium somewhere between 400-500 ish



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Your KH and Ca are way too low. I'd do a 30% water change stat and start boning up on dosing. I'd also drop the lights down to 8-10 hours per day.

Thank you for your input. How do I increase the alkalinity and calcium? What kind of dosing would you recommend? I have the Red Sea Reef Foundation Elements chemicals, but they are probably six years old. they have never been opened. Would they still be good? Defines and maintains the correctly balanced levels of Calcium, Alkalinity & Magnesium

In order to keep corals alive, you should have an understanding of testing for, and in most cases dosing, at least alk and Ca. Your calcium is not 1.03 ppm. I suppose that it's possible for alk to slip to 1.7 meq/L (<5 dKH) if you never do water changes or dose for alk.

There probably isn't a need to break down the tank. Just do water changes, or even 1 very large water change, until your parameters are closer to natural seawater:

Temp 75-80
S.G. 1.026
Alk 3 (8dKH)
Ca 400-450

I would do some big water changes regardless. Did you just start lighting your tank? Diatoms usually bloom when a tank first cycles or if there's silica present. Those are very hardy corals and running your lights for 12 hours, while is a long time, is not going to kill them. You might also want to run some carbon for a bit, just in case. Are you using an RO/DI unit or tap water? If you're using an RO unit, check your TDS, your filters might need to be replaced. If you're using tap water, then who knows what could be in it. It could be copper poisoning or something.