Anyone ever use ultraviolet light for pythium instead of a water chiller?
UV light does a good job of sterilizing what it hits, problem is it doesn't hit everything. Thus shit can still grow on the roots and areas that the light doesn't hit. Yeah it keeps the flowing water sterilized but if there is something growing on the roots the water doesn't have any potential to kill it.
The chiller simply enables the water to hold more dissolved oxygen as water at a lower temperature can hold more oxygen.
Methods like pool shock or hydrogen peroxide are often used to run a sterile system. Others have better luck with beneficial bacteria, products like Hydroguard (thats basically just watered down Southern Ag Garden Friendly Fungicide).
I personally favor the idea of running with bennies as you really can't overdo it with beneficial bacteria. You can have too much pool shock though and it breaks down over time thus making it difficult to know how much you need to add in order to maintain an effective level. The amount used is very small, further complicating the situation. If you change out your reservoir every 2 or 3 days then the pool shock is the way to go IMO. If you run the reservoir for a long period like I do (I run the whole cycle without a dump) then the beneficial bacteria method is the way to go.