I'm running 1.5ml of 29% h202 per gallon. It's on the weaker side of the mix. there's a fine line between frying everything in your res and mixing it too weak and doing basically nothing. You can kill everything organic off in your res if you mix it too strong or add your nutes before the h202 has had a chance to stabilize itself (add h202 to water first, wait 15 minutes, then procede to mix ferts and ph adjust last).
Kuz, you are correct that some good stuff can survive concentrations that kill off the bad. that's the fine line. The beneficials that I am refering to are beneficial bacteria and fungus, these can't survive in their "live" form in h202 concentrations that kill off pythium, what lost is refering to as a "dead" res. At the h202 level slightly above what will kill pythium off, additives such as leonardite (liquid humates, diamond nectar), seaweed (the over 70 different micronutrients, minerals, enzymes, and naturally occuring hormones in acophyllum nodosum or norwegian seaweed/sea kelp), silica, and enzymes do not seem to break down at this concentration from my experience. I really have no idea if there are some forms of beneficial bacteria and fungus that are hardy enough to survive mild concentrations of h202, but when my biologist friend returns from Costa Rica this summer we'll do a culture and see what survived and what didn't as well as analyse the water to see what's going on in there. It obviously isn't breaking everything down, so I am interested to see what survives at what concentrations when he gets back. All the biologist requires is an edible and a bottle of flor de cana rum aged no less than 7 years.
As far as UV light is concerned, I believe it can break down enzymes and proteins and fry your bennies to an extent . I don't believe it's necessary at all. Problems start occuring with water temps over 75 from my experience, so keep the water temps down. 66-68 is a better number to shoot for.
The h202 chemically nibbling at the roots stimulates growth while the added oxygen stimulates root growth as well.