I use pool filter sand in my aquariums. I never have had a problem. It's always clear, never has been milky.
It comes in a 50 lb bag. I take a 5 gallon bucket and fill it half full of water then I pit half a bag of the filter sand in my bucket. I lean the bucket until the pool sand is about 2 inches from the rim of the bucket and with my water hose I swirl the water around in my bucket and keep my bucket leaned to the right. I don't have to put my hand in the bucket. The swirling of the hose stirs the sand up. It's cleaned in about 5 minutes, but I continue for a total of 25 minutes.
I drain as much water off as I can. I have a fine stainless steel strainer and I take the sand out of the bucket with it. When my sand is in my aquarium I add warm water. I always use the tank water thgat has been cleaned. I don't even have to wait for my power filter to clear the tank. It's clear. I add my fish back to the aquarium.
Half a bag will cover my 3 aquariums. My sand is about 3/4 inch deep. . You'd be surprised with how nice pool filter sand looks. The sixe of the pool sand is about the size of small grains of rice.
Make sure your temp of your aquarium is the proper temp or you'll stress your fish and possibly kill them.