Hello' can someone please let me know if it would be safe to use my old sand from my tank ? I had to tear it down cause I had a big out break of algae it took over everything my live rock and even got into my sandbed,so I cleaned the entire tank. I had it for about 4yrs and never had any problems with it. I don't want to buy all new sand if I don't need to cause am poor...what can I do please help....