Hi everyone. I am eager to make a couple changes to my 120 gallon tank and any advice you have would be appreciated. First of all, I am going to change my substrate to pool filter sand. I'll check home depot, but just in case, has anyone ordered pool filter sand of the internet? What is a good place to buy it? I also plan on painting the back of my tank black. What sort of paint would work best, and how many coats? I am also looking into a UV sterilizer. Any ideas on which kind would be good for a 120 gallon?