EMERGENCY!!!

I'm just a newbie, but it sounds like removing the new equipment would be a good first step.

Keep us posted. Good luck to you and your fish.

It is difficult to say what actually happened. In any case, the odds of the problem actually being the Koralia is extremely slim. Do a large water change and test your parameters again.

Perhaps check the Koralia for stay voltage?

How long was the Tang in the tank prior and how much nori/seaweed was he getting in his diet?

Damsel's have a habit of acting like little demons, especially if there's nobody around to keep them in line. Yellow Tang's on the other hand will become stressed by their own reflection especially if they don't have a space of their own. Being that they are constant grazers by nature this will also cause stress if they don't have a regular (3+ times a day depending on size) source of greens.

It's possible that the damsels were bullying the Tang to the point it died from the stress. I'd suggest thinking twice about keeping those damsels around - they aren't a problem in all cases, but I would say the majority of them do cause problems.

Your water conditions look okay - ideally nitrates should be at zero for the best health of corals, but a reading of 10 isn't uncommon. Are you using a good, reliable test kit to be sure the readings are accurate? I'd say the two events, while quite a coincidence. are probably unrelated.

How long have the corals been in your tank? Did they thrive prior to this, or have they been slowly degrading since putting them in?

damsels are the fish from hell, while they are active and easy to care for they are mean. I had 4 in my 120 gallon tank and when i would clean the tank the smallest one of them all used to attack my hand.

While most fish respect "The great hand that feeds and moves rocks" this little guy was having no part of that, the first few times he nipped at my hand i couldnt figure out what was going on, then i stuck my arm in the tank and just watched only to find out it was the smallest fish in the tank!



it really was a pretty looking fish, but after i took him to the LFS and they gave me $8 for him; i am sure he is someone else's problem now. LOL

Good to hear your tank is returning to a stable state again.

Here is a speculation on the issue. WHAT IF...those PH's had some left over chemical residue on them...inside them that is. Where the wire goes in that also gets water inside the casing to.

Another what if...what iff the motor was going bad and maybe some metals were seeping into the water.? Possible? I know sump pumps going bad do it..but PH i dont know.

ONe more wild speculation:
Stray current...but you would know by invert death on mass...like your snails... stray current wipes them fast... plus you should know by when you place your hand in the tnak and feel a slight tingle...almost like when a cleaner shrimp starts checking out your fingers.

Sorry for the losses....