Just wanted to write and share an experience I had with GH FloraShield.
I run a DWC setup with Humboldt Nutrient line. My plants were looking fabulously happy, but as a precaution (because I AM running DWC) I ran some of the FloraShield when doing my most recent res change. I followed the bottle's instructions to a T. (I measure all my nutrients with a 2 oz syringe broken down my the ml.) Anyway, this was my first time using it, and the bottle said to dilute 1:100 in your reservoir and let circulate for 1-2 hours before adding your nutrients. I did this as a protection against root rot - even though I keep my res under 70 degrees and my pH around 5.6.
Well, after 1.5 hours, I came back up to put in my nutrients and all of my previously happy, shiny plants were now all wilted and folded over. A few of the older fan leaves were starting to dry and get crunchy (a sign of chem burn). I immediately drained the res and let just water cycle for the next two hours, before adding my nutrients back in. They are slowly making a recovery, but look NO WHERE near as good as they did before this disaster. I have been running DWC for the past two years and never had anything like this happened before. (I was taught by a DWC guru who has been doing it for 20 years)
Just thought I would share the experience so others might not suffer the same fate :(