My tank is a 65 gal tall tank with 4 clown loaches 3 gold fish a red tailed shark and gobby dragon. The tank has been up and going for 2 or 3 months now but I noticed I have to change about 15 gals of water a week out and the tank starts to cloud up badly a week later. all the levels show good on the test strips but I would like to know if anyone knows why the water clouds so fast and what can I do to prevent this. when I vacum the tank I do not get any old food etc from eth gravel and I carfully watch what I feed the fish. Thanks in advance for any help/advise.