Bubble algae should I buy and emerald crab?

[kwirky]

I've found my emerald crabs quite beneficial to my tank. I have 3 in a 120 gallon aquarium. (along with a black "emerald" crab hitchiker which is more shy, but behaves the exact same as the others). they keep to themselves, and I find them a great invertibrate to have in a tank. I have two left handed hermits that seem to be fine. I'm more nervous about the 1/2" sized hermits misbehaving than the 2" emerald crabs, really. If the hermits perish for any reason, I'm not getting more.

I noticed bubble algae about 3 weeks before I bought the crabs, but now I can't find any at all. But then, my nitrates are < 0.2ppm, and I run rowaphos. I only have one fish in the entire aquarium ATM