AK1, you're doing a great job on the grow, my friend, and you're 100% correct about every method of growing having its potential issues. Try overwatering plants in soil for a few weeks and you'll find root rot ("pythium") is not unique to hydro growers.
Pythium is actually in the air around us and the trick is to NOT give it an environment that's conducive to "making a home" and replicating. This can be a little more tricky in hydro since a warm pool of nutrient-rich water makes the PERFECT home for pythium!
I would focus on three areas to help prevent/avoid pythium (removing it is a different issue!):
1) Are my res temps in check? Once you start getting above 72* F, or so, risks go way up!
2) Am I providing good air/water circulation? Get as many bubbles in the res as possible and let the bubbler run constantly. Make sure water is never sitting stagnant.
3) Are all my plants healthy? The best defense for pythium is healthy plants. The pythium will attack weak plants and any unhealthy plants in the res will put the rest at risk.
FYI...I also have found Dutch Masters Gold Zone to be very effective in helping treat and prevent root rot in hydro using synthetic nutes, but should not be used with organics because it can kill the beneficials.
I hope this helps!