Ryz, you can't use DT's for culturing. In the past you could, when they had just Nannochlropsis algae. Now they mix up 3 different types inclusive of freshwater Chlorella, making it very hard to culture a pure strain from DT's.
You're better off buying seperate cell cultures.
Suggest you read the pinned up threads if you want info on how to culture your own phyto.
I used to do it in the past... have used Instant Algae before, tried DT's and now trying out liquidlife Bioplankton.