growing phytoplankton

[dadonoflaw]

i am starting to try and grow phytoplankton that i got from a local hobbyist. my questions are how important is it to grow it with freshly made saltwater as opposed to tank water? he made the argument that tank water is more stable which makes since but i have heard alot of people stress the importance of using fresh saltwater. secondly can i use miracle grow all purpose plant food? i have this available since i grow land plants and since it contains the same nutrients i wanted to know if this works. lastly can i use a 100 micron filter sock to split cultures for the purposes of removing debris. i have this in my fish drawer so i was hoping that would be fine temporarily. sorry for the long post.