I am not an expert, but I have been in the hobby for about a decade. I set up a new (used) 75g. Its a real basic set up. Aqua Clear Filter, Air Pump, Heater. Sand Substrate, a few large rocks and a couple ornaments. 5 very small african cichlids, a blue crayfish, 1 black ghost knife and 3 balas.

I know how to cycle a tank and I know about the 6 week nitrogen cycle. I know about over crowding a tank, but these are all very small fish. I set the tank up almost 3 months ago, let it cycle for a week before adding anything living, then added the first fish, the rest a week later.

I did regular water changes of 20-40%. My PH is perfect. The tank looks good, very clean and the fish are all very active and healthy.

BUT...I have never been able to get the water perfectly clear, there has always been a slight blue-ish white cloudiness to the water.

This is the first tank I've used sand in as the substrate. This is the only thing I can think of that would cause it.....Any suggestions?

White cloudiness could be caused if the sand was not rinsed entirely, but typically white cloudiness is a bacterial bloom. Out of curiosity, since you have cycled the tank, do you know what your actual parameters currently are? Nitrate/nitrite/ammo? Bacterial blooms are pretty normal..especially in newish tanks, but it shouldn't be there ALL the time, the water should eventually clear from it. Wish I had some more helpful suggestions for you.

No, I don't have the chemical readings, but can test them tomorrow and post if necessary

I wouldn't say it was necessary. It's just helpful sometimes in diagnosing what is wrong with the water, but honestly I personally don't know outside of maybe unrinsed sand or a bacterial bloom. Hopefully someone with some better suggestions will be able to help more.

What other types of decorations do you have in there? anything that could be leaching into the water? Bacterial blooms look white, algea blooms green. Its the blue thats throwing me off.

are you sure all the rocks and decos belong in the tank? Did you ever use the rocks in a tank before? if not did you test them? if you take them out and pour some vinegar on them see if the rocks bubble up or fizz, if they do dont put them in there.

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90 gallon, 1 Iridescent shark, 2 Pleco, 3 Goldfish, 5 Cory cats, 2 Nerite snails
5 gallon hex, Blue Crowntail Betta, 1 nerite snail,

Yeah, the decorations are all aquarium decorations from PetCo, all but 2, those 2 came from my brother's tank, similar set up in his tank.