Desperately Need Help!

[merlyn2221]

My fish have all died!
I have a 55gal. tank, established for tropical fish two years ago and converted for Africans in the last month.
I run two filters: Marineland's Emperor BioWheel (biologically established for the two years I have had the tank) and a Fluval 304 (added last month).
My pH tests at 8.4, total hardness is appx. 150-200 ppm, alkalinity is appx. 400 ppm. Temperature is 81 degrees. Nitrites and nitrates are both 0 ppm. Ammonia is also 0 ppm. My substrate is pea-sized gravel, too large for the fish I have bought to put into their mouths.
I use Aquarium Pharmaceuticals aquarium salt (according to the manufacturer's directions) on a daily basis.
Each time I have brought a seemingly healthy fish home, it dies within a few hours, a day, or a week to 10 days. I cannot figure out what the problem is and am not going to buy anymore fish. I have already lost 5 (too many).
I am driving myself crazy reading books/online information, asking people questions who work where I have bought the fish.
Do I need to test the calcium, magnesium, and potassium levels in the tank indivdually? Do I need to test the oxygen saturation of the water? If I do, what do I use to do so? PLEASE HELP! :(

[jonah]

My pH tests at 8.4, Nitrites and nitrates are both 0 ppm. Ammonia is also 0 ppm.

I use Aquarium Pharmaceuticals aquarium salt (according to the manufacturer's directions) on a daily basis.

I think it's nearly impossible to get down to 0 ppm with nitrates.

Are you adding salt everyday? It sounds that way in your post. Salt doesn't leave the tank except when you do water changes. If you add salt every day it will eventually get too salty for your fish. I don't use aquarium salt at all unless I'm treating a stressed fish. If you have oversalted the tank I'd do a 90% water change, add the dechlorinator and not add anymore salt. That would dilute the salt to an acceptable level.

I wouldn't bother testing the calcium, magnesium and posttasium. Those are more important when running a reef tank. The rest of your numbers sound good. Your oxygen saturation should be excellent with the filtration you mentioned.

When your fish die, do they always die the same way? I mean the way they look or act before they die.

[jnorris]

I would do a full water change and start new. The salt is curious. I only add salt as I do water changes.

I am with jonah on this one..

[merlyn2221]

Thank you to the people who posted a reply to my dilemma. :D

Jonah, in answer to your question: yes, they do all die in the same way. I am now beginning to think it was the oversalting of the tank. The fish die in full color, fins spread, and gills slightly raised...as if some toxin is in the water. People where I bought the fish put salt into the tank daily. I could not believe this since I kept tropicals for years and salted only when treating a sick fish or during a water change, as well.

Thanks for the advice. I will be changing the water to be sure it is habitable, and wait about a month before I get any more fish! :)

[SGypsyMermaid]

People where I bought the fish put salt into the tank daily

they are probably also doing daily water changes, or they have a water changing system that is continually changing water. salt does not evaporate, so if you are not removing it with water changes, then it stays in the tank and builds up if you add more.

[jnorris]

You shouldn't have to wait that long to get new fish. Change your water and get some cheaper fish to help cycle the tank.

If you can get some filter media from a known healthy tank that would help also.