The reason is most likely in the parameters. What tests have you done to check? Check phosphates as well as the normal gamma of tests. A pic would be helpful to see what it is. Can it be diatoms? They are caused by silicates.
Post the parameters that you have checked and it may help to resolve the issue.
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40lbs livesand(bag from LFS
), 30lbs live rock(LR
2 O. Clowns
1 peppermint shrimp, 5 red leg hermit crabs,
4 mexican turbo snails, 15 nassarius snails
ricordea mushroom, candy cane coral,
super color polyps, hairy mushrooms
bubble coral, hawiian feather duster
coralife lunar 2x65, HOT magnum canister
10 Gal refugium(chaeto) & seaclone skimmer