I am considering shutting down the smaller of my two tanks and combining the livestock. One concern I have is putting two urchins in the same tank. How would I know if I am starving them? What signs point to starvation? I dislike algea in the tank as it is and wont to let the tank be dirty just to support the urchins - I'd rather find a new home for the urchin. The tank is 70 gal and the two urchins in question are about the size a tennis ball or a little smaller.