Glad it's looking better- hope it's still in good shape. Lots of arguments about feeding routines, but if you're using the container method, once every two/three days or so should do it- and I'd make sure the water remained warm- some people float a small tupperware container in the tank, lots of ways to go about it. If you're adding it to your tank, I'd dose it about once/twice a week, but that will put a strain on your parameters, and by all means turn off your skimmer and returns for a few minutes after feeding to let it distribute through the tank-
Also- calcium and alk levels are critical for success with clams- which I'm sure you already know-
I have no clue if you can culture DT's; there are threads here somewhere that give fairly detailed instructions on culturing phyto. My hunch is it's not possible, and my opinion is it's a heck of a lot less trouble to buy it, but I've seen people who swear by "growing their own." Hope this helps-
