Ok guys I'm having a very ruff time with both my 75g tanks and need some help before just tearing them down for good. I have lost every fish with 24-48hrs. Here is my story... I started with a 55gal and transported live rock from a tank that had been up for yrs as well as some live sand and and reg crushed coral/mixed. It had been up and running for about 2mos and all the fish were happy.(Clown, yellow tang, gobies). My gf wanted her Blue Hippo tang that her daughter had in her tank which wasn't doing good at all. The fish against my better judgement would have been flushed but she wanted it. You could tell it was sick maybe hole in the head and so on. The Hippo lasted about 1wk before belly up. All my fish started dieing afterwards 1 at a time=( It started with the gobies,clown fish. I though maybe it was there time then bought 2 firefish and one at a time days apart they went everything bedsides the yellow tang. The 75gal now had been up and running with 150lbs of sand with 5lbs of live sand thrown in. It had around 60lbs of live rock and i was going to use this tank more for a few fish. So the yellow tang went in (all levels normal) and looked better for about 5days before the color started looking bad. I then tested the levels at a marine place against mine and everything looked great??? I added the tang back in and with in days the tang was dead! I tested the 75gal against the marines test kit and again all levels were fine??? So I waited a few weeks and decided to try again... Bought a soliderfish(popeye) and 2 saddle back mated clowns. The next morning woke up to one of the clowns on the floor=( The next day the other one dead in the tank??? That dead I had traded for a nice light set plus 2 tangs for my 75 gal and the fish seemed good in the 75 swimming eating etc. I figured the 75gal was safe??? So i started to notice the popeye solider fish was getting popeye the bacteria infection on his eye? Come on man!!!! I treated it and thought the fish looked better after 4 days then belly up! 4 days later the Sailfin Tang had red ucler like around the mouth spreading up to the top area of it's head? Treated it and day4 dead along with the scorpin tang! The guy at the marine place told me it had to be a bacteria infection that had spread throughout being transported from one tank to the other from the tang. So as far as the tank set ups all are fine plenty of live rock good filtration and so on. I posted this on another board and my replies said that the tank was not cycled which i saw my spikes then dips and respikes of ammonia and nitrates./nitrites and so on. I was told to wait 6mos before fish and a yr for coral? I agree somewhat but how many marine places set up saltwater tanks all the time brand new? I'm not to new to saltwater either. Also was directed towards adding Floramin to the tanks to kill whatever? I'm very losted and confused please help.
Thanks in advance,
Dan

Did you clean the tanks with anything? It sounds like the silicon might have something in it that could be leaching into the water and killing everything. Thats insane that you have lost that many. thats got to be something more than ammonia spikes. It could be the cycle....but I would venture out and see what else is in that tank.....do you use air freshners? My buddys wife used an air freshner........wiped out his whole tank and all of his corals. What about remodeling your home? Any carpet? Wood? Glue? All have toxic chemicals to our tanks.

major stirring up of live rock and substrate can cause super shock, effecting everything real bad.

could this have been possible