My 30 gallon tank has been set up for years. I only have fancy and fantail guppies in it. About two weeks ago they started dying about two or three a day. I have done a water change, vaccuumed the rocks and changed the filter twice. I have noticed that the water is kinda of grainy looking. My PH checks out okay and I am going this weekend to have a water sample checked at a fish store. About the time the fish started dying I had bought five new fish who are doing wonderfully while all the others are croaking. At first I thought it was because they were just old but all stages of my fish are dying from new fry up to the oldest adults. I am so frustrated now I am on the verge of throwing away my algaefied decorations, all the gravel, scrubbing out the tank and just starting over. I have beautiful guppies and don't want to loose any more. Please :help:!