Highly recommend Hydroguard, allows me to grow DWC in the desert with high water temps. Also should help with that brown root rot that's starting to show on your roots in pic 4. GL growmie!
@LuckSackGrows, Hydroguard isn't in stock anywhere in my country at the moment. Super annoying but making look at alternative solutions.
Like solution temp, more air, and I have now changed the solution and tweaked it by adding Advanced Nutrients tarantula. Which has the same microbes as Hydroguard.
So far everything root wise is looking ok now