mag-float..are they reef safe?

[beginnermatt]

I've noticed this cleaners in some rtank pics? Are they left there all the time or removed when finished? Didn't know if anything in the mag was bad for the water. Thanks..

 

[richard rendos]

I don't think they are "bad", but I use mine and then remove it. I think it lasts longer if stored outside the tank, and I think it looks tacky left inside.