Try to make this as short as poss...well my 100liter tank burst and I managed to save all my fish, I bought a new tank set it up with the old gravel and filter to help it to hopefully cycle a bit faster....check water with test kits..ph fine and kh and gh all fine so put the fish in.....the water never managed to ever look crystal clear and a week later I woke to find all fish dead checked water and the ph was as acid as can it could get!!! So I scrubbed the tank and all the contents and started all over again.......tested the water all is fine put just two cold water fish in........the water is again cloudy parameters are all good so why oh why won't the water clear boo hoo *ALL**SICK*