IT IS GOOD FOR YOUR TANK, IT HELPS BREAK DOWN THE WASTE. FROM MY EXPERIENCE IT GROWS ACCORDING TO THE AMOUNT OF WASTE IN YOUR SYSTEM, IN MY TANK AT ONE PIONT I HAD 1 YELLOW TANG 1 KOLE TANG AND 1 FOX FACE ALL BETWEEN 4-6 INCHES, 2 CLOWNS 2 DAMSELS AND A WATCHMAN GOBY ABOUT 3" EACH, AND THEN I DECIDED TO SWITCH OVER TO SMALLER PEACFUL FISH SO I GOT RID OF EVERYTHING EXCEPT FOR THE 2 CLOWNS AND THE GOBY AND THEN THE CORALLINE ALGAE BEGAN TO DIE OFF ABOUT 30% OF IT JUST FADED TO A WHITISH COLOR AND THEN DISSAPEARED, NOW THAT I'VE ADDED MORE FISH TO MY SYSTEM IT IS BEGINING TO GROW BACK AGAIN.