First introduction of fish unsuccessful

[jeb]

After going through my initial setup cycle (and seeing 15 damsels die), my water was tested and deemed perfect by the fish store that tests my water. Then I bought 2 tangs that died within 3 days. Then I changed 25% of my water, replacing it with the store's water, that is supposed to be perfectly balanced-I did this to see if maybe my water at the house is not perfect. Then, I put another damsel in, that died within 48 hours. Again my water was tested, including pH, and was deemed perfect. I have a heater, set at 76% (before, I didn't have one, and the temp was at 71%, which could have been a problem). I recently put some more gravel in and a few plastic plants, but I cleaned both before putting in. What seems to be happening to the fish, like the 2 domino damsels that I just put in 2 days ago, is they turn pale or gray, then swim nervously, then die. Anyone have any other clue as to what could be going on? The death count is at 20. I have been out of the saltwater hobby for about 10 years, so I am out of practice and have just been relying in the fish store for help.

 

[jeb]

The store I go to seems to have a good reputation in Houston-it's called Aquarium World. They did say that people think they are aggressive in getting the cycle started by using so many fish, but that they believe in the method. Of course, they, like me, didn't expect the number of casualties.
I cleaned the gravel and the plants according to instructions on the packages. For the gravel, I used a hose and a bucket, filled it up partially, poured out the water, refilled, etc. I wonder now if I should have rinsed it more than 2-3 times-after putting it in the tank, it took a good 24-36 hours for the dust to settle. Do you know if this gravel (I think it is called aragonite) can contain toxins that take a lot of effort to wash out?
Do you think lighting could have anything to do with it (I know I'm reaching here, but I'm trying to look at every possibility)? I have 2 tubes that came with the tank, one blue and one white. I keep the lights on 11 hours a day on a timer.
As far as water, they test for salinity, ammonia, nitrites, nitrates and pH. The store owner said that there are other water problems that aren't detectable by their methods, which is why I was convinced to use their water rather than mine, thinking that mine might not be very good.
Thanks for the response-sorry to be so long-winded.

 

[broomer5]

Are you using tap water ?
If so do you use a dechorinator prior to mixing the saltwater ? Residual chlorine and chloramides will kill fish.
Circulation - what size tank and what type filter, powerheads ? Gas exchange is important as well, especially in deeper tanks.
As Baron mentioned - did you clean the tank or use any household detergents or solvents ?

 

[jester]

What kind of filter do you have?
It sounds like there are either toxins in the water or lack of filtration. How big is your tank?

 

[dirtybilge]

Give the people on this board more specifics on your tank. additives, test kits, size, ls, lr, filter, skimmer, and if you don't have these things look into aquiring them. You have a big tank problem.

 

[jeb]

I used tap water initially, but the last change I did (25%), I used the store's water. I used a declorinator in my water (1 drop per gallon), but didn't use it in the store's water. Do standard test kits test for chlorine/chloramides?
I have a new 75 gallon acrylic tank with a biological filtration system (the bio-balls). I have a Cap 1800 powerhead that came with the tank. Can you explain gas exchange?
I did not use any cleaners when setting up my tank-just water.
thanks,
Your help is much appreciated

 

[sandy]

Why 'o why use damsels to cycle? Soooo cruel. IMHO. Sorry to hear about your loss. Hope it works out.

 

[ohscc]

tell us:
salt reading?
Nitrate?
nitrite?
ammonia?
ph?