Fish dead...?

My 2 yellow tail damsels are both dead. No signs of sickness or anything to be alarmed by. My Coral Beauty hasn't been looking well, and today he looks really bad, very pale and splotchy. I did my weekly maintenance today, 34 gallon Red Sea Max born Feb 14, 09. Changed approx 3+ gallons of water. Noticed the dead fish. I tested Amonia, Nitrite, Nitrate and Ph. All at right at 0, except Ph which registered at 7.8.

Friday night we had a bad storm and power was out for a few hours, a couple of weeks back I added 2 crabs and 2 snails. Any ideas?

How do I raise my Ph back up? What do I need to do?

 

Any way anything could have slipped into the WC that wasn't usually present? Is your tank grounded/have you checked your wiring?

 

I have it connected to a power strip. Nothing I have noticed weird about that. What could have slipped in my WC?

*Could the Coral Beauty have given the other 2 a disease and it killed them?

What causes Ph to drop? I have usually been at 8.2 - 8.4.

 

Whats your Alk at?

 

I didn't check Alk, but assume it is low if my Ph is at 7.8. As a quick band-aid I just dosed for Alk.

 

I was just thinking any kind of chemical/toxin that might not be usually present. Something in the water/salt or in/on the mixing bucket. I would also go ahead and check your alk, especially if you just dosed it raise it.

 

The Coral Beauty has been not looking very good for a couple days now, kind of pale in color and splotchy...today he looked really bad, the YT's have been fine, all of sudden they are dead. Weird. Not sure to make of it. I change my water and clean the tank every week and thought I had been keeping on top of things. All I have in the tank is one red macro grape algae plant for decoration, no corals. Not sure how this happened.

 

ALK is 71.6kkm

 

did you dechlorinate the water?

 

Yes. I use RO water.