DT's live phtyo expiration??

[tomzpc]

Question, is it neccessary to turn off the skimmer when dosing? If so, when i turn the skimmer back on, doesn't it remove all the DT's?

Up to you. I never turn the skimmer off when I dose DT's but I do tend to dose it pretty heavily (at around the recommended dosage). It's probably a good idea to turn off skimmers during any kind of tank feeding but I'm much too lazy for that. =)