possible alkalinity and water hardness problems

[jenkscam]

I have set up a new 55 gallon freshwater aquarium which has been set up for approximately two weeks. I am filtering with a Marineland Penquin bio wheel model 350 and an Aqua Clear power filter model 70. We have added gouramis, pictus catfish, and barbs. The majority of the fish have died and we have continuously tested the water using Tetra Easy Strips. The water has been cloudy from what I figured is new tank syndrome but has started to clear since adding the new aqua clear power filter. Everything on the test strips look good except for water hardness (gh) and total alkalinity (kh). The water hardness is reading very low at 0ppm showing very soft water and the total alkalinity is reading very high, above 300 ppm. The ph has been stable since setting up the aquarium between 6.8 and 7.2. Could the water hardness and total alkalinity readings be the cause of the fish dying and if so how can you correct these problems. Thanks.

 

[librarygirl]

Hi and welcome! I doubt that would affect the fish. Most likely you just added too many fish to an uncycled tank and the ammonia levels are harming them. The test strips are very inaccurate; a good liquid test kit like the API Master kit is best. I'd do a 50% water change daily with dechlorinator (Seachem Prime is one of the best) until you can get your liquid test kit. You might want to give these links a read too:
I just learned about cycling but I already have fish. What now?! - Aquarium Advice
Guide to Starting a Freshwater Aquarium - Aquarium Advice