of course you know i make my own seaweed tea.
but, of more interest is, are fresh water aquatic plants of the same quality as ocean seaweed. i looked into this several months ago and didn't really find an answer. but on further investigation it appears, it really depends on what's feeding your fresh water aquatic plants. from what i have read, it appears no, ocean seaweed is the best. fresh water will suffice as a soil conditioner but overall ocean seaweed is the best.
here is what have learned with seaweed, i use dried seaweed and rehydrate it. but before putting it into my soil i have to let it rot, really turn mushy. if i just let it rehydrate and then blend it into my garden soil, my dry, arid temperatures turn the seaweed back into dried seaweed. hard crusty strips. i then dig this into the soil and wet thoroughly.
let me know if you want me to describe how i make a seaweed tea but you can go to plantea.com and they have instructions.
good luck and thanks for keeping our earth green.