Melosu - I have heard that the can devestate a hair algae problem - is that incorrect?
I have i think turned the tide of the hair algae fight.. I see it dying, like shrivveling up in places but it is so thick in other spots its hard to kill. I put a phosphate pad in my filter, doing PWCs with RO water (it isn't 100% phosphate free, i tested, but its better than tap) and reduced my photo period. Added hermits and a few snails. Don't feed even every day anymore, partially because my fish just eat the hair all day basically. I don't know what else I can really do, but on one rock which is very shielded from the light it has almost completely died off. My overall phosphates are down but not out.
I still like the crab though because he's cool and Ive always been a fan of crabs ever since i was a kid catching blue claws.
