You DO need to choose if you want to do a living reservoir with bennies or a sterile reservoir with something like bleach or chlorine. I don't recommend doing neither. H2o2 kind of sucks for maintaining a sterile rez. And it's expensive. Don't buy into the hype of h2o2. Bleach is a hell of a lot cheaper and works 10x better to maintain a sterile reservoir.
If you want to do sterile, you can use 0.25ml-0.50ml per gallon of nutrient solution added back every 3 or 4 days. Nom scented plain clorox bleach only. Or the cheap bleach, but make sure it's not scented or special like the gel crap.
For a beneficial res, or live res, find the heisenburg tea recipe. I don't think he created the tea recipe, I believe it was richyrich from another forum. Both have the same recipe I believe.