1. depends
2. depends
I use DT's (live phytoplankton) and I also add rotifers which I usually just pour a squirt into the tank. However, once in a while, I'll put the bottle in the water and squirt it directly on my filterfeeders (mushrooms, dusters, and unidentified encrusting SPS). I feed them 2 or 3 times a week. I'm sure there are a million opinions on this, so all I can do is tell you what is working for me (so far). HTH