hi my name is jon and i am new to this site. i have had my 30 gallon aquarium for 20 yrs with fish only and recently have upgraded my lamp for corals. i have a medium sized frogspawn, medium size leather coral, medium size sebae anemone cleaner shrimp, 2 emerald crabs, 5 turbo snails. anyways since i have upgraded my lighting i started getting a fuzzy dark green hair algae not too long. changed the bulbs in my lamp and now the algae is a dark reddish brown color still stringy tho but looking like dead algae. i have been doing a 5 gal water change every week and sifting the gravel but 2 days later the floor is dark again. what is causing this and is there anyway i can section out my tank and remove the gravel little by little and change it with sand?