Sea urchin

[aftrhrs]

I have a black sea urchin with an orange eye that was the size of a small baseball to the tips of his spikes when I bought him. He has since eaten 6 emerald crabs and a few hermit crabs. He is approaching the size of a basketball now and I don't know if I should keep him anymore. The emerald crabs did a nice job of cleaning the tank and now the tank is starting to grow some green hair algae. How many people keep a sea urchin in their reef and how do you keep it from eating a crab dinner daily?

 

[reef_magic]

sounds like you didnt get a reef-safe urchin. some are carnivores while others feed off the algae in our tanks. you might wanna replace him, especially if he's the size of a basketball
got any pics?