I have a very established 3 gal pic that I would like to know if I could add an sps coral too. I don't have any fish only inverts. I do have soft corals in there and for critters there is 2 sexy shrimp, 1 cleaner shrimp, 1 hermist crab, 1 algae eating cowrie, 1 nassarius snail.
my lights are 18...