none at all, and so far so good, polyps and feather dusters are growing naturally, i haven't bought a single one, they must be growing from the lr we purchased
I use a Berlin Hand-on. I would never run a tank without it. It takes out so much crap. Once I forgot to turn my WET/DRY back on after I was cleaning it, it was turned off for a week. But all my levels where fine, probably thank to my skimmer
I have the much disputed sea clone. It is working great, finally with mods. I clean it out when the debris gets to about 1/2in. and I am pleased with it so far. So far, no problems at all.