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Not using hydroguard should I use it ?
Here's the root are they healthy
"The roots are healthy" so far. Your res is at 24°. That's high enough that your chances of getting root rot will skyrocket.
"Should I use it?"
It's a good option. I can't tell you what to do because I don't know your situation. I'll give you advice based on my knowledge but I won't make
decisions for you.
A res in hydro uses "bennies" (beneficial bacteria) or it's a "sterile res". Bennies include products that have beneficial bacteria to ward off bacteriological and fungal growths. I started using Hydrogaurd when I started growing (only 18 months and 3 grows, mind you) and it's worked well for me. When I swap a res, the water temp can be as high as 25° but my water chiller drops that to 20° in less than 4 hours. I've had zero problems with root rot.
"Orca" is product that's similar to Hydrogaurd and it gets a lot of positive comments from its users.
Running a "sterile" res means that you're adding chemicals to kill bacteria and H2O2 is the most common. It sounds very straight forward - add X ml's of H2O2 and that will keep things working smoothly. The only hitch there is that you need a higher strength H2O2, not the 3% (?) version.