My fishies keep dying!! Please help!

[elaine24]

I have a 54 gallon tank with LR and a live sand bed, sea clone protein skimmer and two powerheads. I've had it for about 6 mos. i cant seem to keep my fish alive...something always goes wrong. My first big purchase of fish lead to my Koran Emporer getting a cloudy eye and so i treated it with Melafix(?) which in turn killed off my whole tank. So we did a 100% water change. then after a week of letting my tank settle we purchased two cardinal fish and a strawberry pseudochromis(?) and the cardinals died. My lone survivor has been my strawberry guy. I went ahead and got a threadfin butterfly about 2 weeks ago and he started acting funny after i did a 5 gal. water change. He got a white spot on him, and he was still eating fine. My hubby surprised me with 3 fish he got from a friend who was getting rid of his tank. So now i have a cinnamon clown, fire clown and a black tail damsel with my strawberry guy. Woke up this morning to turkey baster off some algae on my LR and found my butterfly DEAD!! All of my tests came back clean when i tested two days ago. i'm just wondering if I am doing something wrong!! I dont want my fish to keep dying!! Was there something i could do to prevent this death?? The death of my cardinals was surprising because they seemed fine. My hubby keeps trying to get me to get rid of my LR because it just seems to be an algae magnet. All of my money has just gone down the toilet because they are alive for about 2 weeks then go belly up, except my strawberry guy....please help. I'm willing to try anything.
Oh yeah, i do have a 10 gal that i use to age my saltwater. i do weekly 5-10 gal water changes and maintenance my tank once a week. I at one point began to buy bottled purified water for my tank because i thought our water might have other chemicals in it...all that did was drive my protein skimmer crazy, so i quit.
Thanks for any advice...

 

[peasly1]

did you let your tank cycle when first set up?when you changed 100% of the water it will need to cycle again.about 6 weeks.if anything might live it will be the damsel..what is your salt level

 

[elaine24]

yes, my tank cycled before i added any fish. wouldnt my tank show high levels of chemicals (like ammonia) if it cycled again?? Because my tank hasent had any levels since it finished cycling. My PH is at 8.0 and my salinity is at 24.

 

[beth]

What do you mean your salinity is at 24??? Please take another reading. Your salinity should be at around 1.23 and your PH should be at around 8.2.
Additionally, when you are having problems with your tank, especially serious problems like fish deaths, that is not the time to add new fish, let alone multiple new fish.

 

[elaine24]

Sorry about that, my salinity is at 1.023. My hubby thought he was being nice by bringing me new fish. But they all seem to be doing great...havent had any concerns, but yet its still too early to tell if they'll kick the bucket too w/in a couple of weeks.
I'll do another test tonight and if needed I'll add a buffer.
Thanks for help.