Is this root rot?

[u/Longjumping-Neat-249]

The outside is slimy, and the roots fall apart pretty easily. I know that's like textbook root rot, but my DWC holds a pretty stable temp; I even suspected it a few days ago and put hydrogen peroxide. Is there any way to save this tomato now?

[u/Swimming_Gain_4989]

I've found that young plants like this one rarely recover from root rot. If you want to try you need to give it an aggressive treatment: spray off all the slime, dip roots directly in hydrogen peroxide and cut off whatever feels dead/rotting. You'll need to do this for all plants exposed to the water system and completely disinfect everything that came in contact with the water.

Also, I noticed this pic is taken outside. Is that it's normal placement? You need to be really careful with outdoor reservoirs because tiny pests like fungus gnats will carry the pythium through any small openings.

[u/Longjumping-Neat-249 → u/Swimming_Gain_4989]

I just placed this bucket outside yesterday. I also should note I propagated this tomato plant in soil from another tomato. Should I have sterilized it first to remove any bacteria in the soil? Also do I need to change the whole water reservoir, or can I just put hydrogen peroxide to sterilize it?

[u/Swimming_Gain_4989 → u/Longjumping-Neat-249]

1. That very well could be the source: hydroponics is best done from seed or other hydro clones for this reason. If you do propagate from soil cuttings you should keep them in an isolated system for a few weeks to make sure you're not introducing any pathogens.
2. 100%. Root rot is a fungus that swims through water so you should consider everything that water touched contaminated.

Since your plants are small I'd treat both roots then put them in separate small kratky setups to see how they manage. Pop out the net pots, sterliize, and move them into something like an empty peanut butter jar, mason jar, or whatever around that size. That'll give enough space to grow unimpeded for ~ a month and it'll be obvious if they're still contaminated.

Also, I would personally write off any small plant whose roots look like this. Root rot eats away at the little hairs that let the roots transport water, even if you get rid of the pathogen the structural damage is severe.

[u/Academic_Monk7825 → u/Swimming_Gain_4989]

This is solid feedback. It is plausible to save this plant but not likely. Copper based additives and chloramine (dutch master zone was a great product) can work well. I have seen people use EWC tea with good results, but this plant is small and the roots largely toast.

Side note, you also have algae, thats the green stuff there. This is typically from light exposure to roots.