my fish dies

Question
hi sir
please help me my salt water tank r 50 gallon and all the fishes i use to add
dies within two days at most within 2 weeks i used to load damsel and crown
butterfly and picasso and star fish the only survivals was couple of demsel
from about 15 damsel i loaded them to tank not all once but as groups of 4 maximum my salinity is good my ph is 8.5 and nitrate 0.5 so am going crazy
why they donot survive i use 200 gallon skimmer and gangster  ehemi filter
pro 3 and wave pump and my temp around 80 Fahrenheit to 83 and i never
over feed . please help me asa u can , thanks  

Answer
Hi Motassem,

I am sorry to hear of the death of your fish.

Firstly, make sure you get all of the dead fish out of your aquarium immediately, because as you know, decaying fish will quickly cause water chemistry problems, which will harm the remainder of your live fish.

Tips: In the future when you add more fish, add them gradually, one or two at most, at a time.

Also make sure your water chemistry is adequate. Do this by carefully checking all of your water parameters with quality testing equipment. Tests should include: Ammonia, Nitrite, Nitrate, Phosphate, pH, Salinity, and Temperature. If you plan on doing a coral reef aquarium, you would also check calcium and magnesium levels.

Lastly make sure to add some beneficial bacteria to your aquarium to help with your biological processes and nitrification. A good product to use periodically is Brightwell Aquatics MicroBacter7. This product will help ensure that you have a continuous supply of beneficial bacteria to help break down nutrients. See the link below for more information on this product.

http://www.ocreef.com/brightwell_aquatics_microbacter7?category_id=4956

Regards,
Dave