@Grow15,You may be okay with the kelp one but contains organic material and the general rule is no organics in DWC. I cant tell you for sure sorry. Hydroguard is the best for your situation, if you can get it where you live. I live in Canada and cant get it here. Here is a user "growdiaries.com/grower/roberts%22 who is very skilled with DWC, I'm sure he would be kind enough to help you more.
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