This kind of trouble was why I went with RDWC from the beginning. I had trouble with anaerobic microbes that nothing would solve- until I got my water temps down below 68F. Once I did that, I never needed to worry about rot or snot again, full stop.
I use chemical fertilizer, no organics at all. I've used bennie teas but they made little difference either way.
Once I got the temps to where I wanted them, even intentionally adding slimy water(!) had no ill effects, demonstrating that cool water is the cure for pythium. Why? Rot is anaerobic- and the colder the water, the more dissolved oxygen it can hold. Getting the water cold enough solves the problem at the source; the water itself.
The suggestion about covering your buckets with an insulating board was a good one; this prevents water from warming up and keeps roots in the dark, both are necessary for good root health. Personally, I use sheets of foil covered foam board cut to cover my tubs and they work great.
How did I get my water temps down? I used a water chiller. Again, since I knew I was going to be running RDWC, I went ahead and bought a big unit with the intention of using water chilling as my indoor climate cooling system as well. After some experimentation, I found that it works better than AC and uses less power.
I use hydroton and netpot bucket lids just like you do. I do NOT use air pumps or airstones, however- instead I created waterfalls in each tubsite which mix, aerate and agitate the water- and splash water above the waterline so roots dropping out of the netpot get wet on their way down to the waterline.
This approach uses drastically less power (one pump now does everything for many tubsites) and adds less heat.
For simplicity's sake, I run my small rooted clones in ebb n flood tables until they're a foot or two tall, then transfer into RDWC for bigger growth. How big? Four feet tall in veg, and 6' in bloom! They produce 'about a pound'- each.
View attachment 3393439
It's all about your water temps and appropriate conditions. You need to use the best instruments you can in order to know what your water conditions are like. Not having a good EC meter in deep water culture is like driving a Corvette with a blindfold on- you're going to crash, it's just a matter of when. I use a Blulab combo meter that digitally reads pH, EC and temperature. Yes, it's expensive- ONCE. Watching batch after batch of babies have problems is expensive every time.
The water temps were key to eliminating slime- I'm serious when I say that I do not clean my tubs between runs other than a quick rinse, I NEVER use sterilants and I don't use teas. Even when I introduce pathogens into the water intentionally, it doesn't survive because water conditions don't allow it to.
I hope this helps- best of luck!
