Just saying you don't need a pump or airstones, you just need to slightly move the water.
Think of a slow moving stream , it picks up 02, without any violent water movement.
Totally agree.
I think I will borrow a o2 tester and check my rez when I set back up here next month.
A friend of mine bought one.
He:"Biggest waste of money ever."
Not because it did not work.
It worked well, but just the slightest movement and the water had maximum DO all the time.
So as long as the water moves a bit, you're good. If you have enough surface of course, and not too much roots.
I wrote it before (I feel like a parrot): I visit a hydro greenhouse frequently.
They have a basin. 1.5 ft high. Rafts with different kinds of vegetables and herbs.
They only stir the water every half hour or hour for 5 minutes. They use an underwater pump. It creates just a small wrinkle in the watersurface. They have maximum DO all the time.
They also don't care about the heat that much. Even the last few days when the temperature in their greenhouse was above 40 degrees Celsius / 104 degrees Fahrenheit. The basin did not reach that temperature but it was pretty high as well, because we did not have cool nights. It was above 25 degrees Celsius / 77 degrees Fahrenheit at nights. I think if the heat would have lasted longer, they would have taken measures, because they also know that 77 degrees is a good maximum temperature for roots.