Use of Phytoplanktion in freshwater

[bajanflyingfish]

I want to try and grow Spongilla, a freshwater sponge, I will have 7 in 2 thirty gallon tanks  (14 total) and they will arrive 2 inches in diameter. Their ostia are 50 micrometres so even most solutions of zooplankton will have particles that are too large. Unlike most if not all saltwater sponges, Spongilla can be photosynthetic so ideally, they will mostly use the food for growth and not energy. I want to know if I can use something like Seachem's Phytoplankton solution in a community freshwater tank. The main concern here being any odd chemical effects the solution may have. These are the chemical ingredients that concern me in content order: Sodium chloride (salt), Acetic Acid ( apart from water vinegar is mostly this), Ascorbic Acid (?stabilized? vitamin c), Citric Acid (will probably lower ph a bit), Astaxanthin (organic pigment). If I dose 1 ml weekly or less, I might be adding 0.5 mls of salt. One of the tanks should already be slightly brackish (it’s not right now) and the other can probably handle it. Sorry for making this so long, any insights and experience is appreciated.

[Clown79]

It should say on the bottle if it is FW safe. Seachem is very helpful, try emailing them.