you can buy the high percentage h2o2 at beauty supply stores.
I sterilize with a 20 percent bleach/ water mix. If you keep you nutrient well shielded from sunlight, algae should not be a problem and you shouldn't need to do any kind of sterilization during the crop cycle. only between them.

I also use bleach/water mix. I had a batch of seedlings die with some sort of fungal infection. I let them soak in about a 1:10 bleach water mix for about 30 minutes, then rinsed them throughly and replanted, and the second batch was fine.

(Note, also had to fix what caused the problem inthe first place, but the fungus was completely killed by the bleach) :)

Best of luck!

Thank you both for the advice.
Another reason you may need to sterilize your tank is due to root rotting though, grizzman, which can happen with 0 sunlight in the reservoir.
Check out the link at the bottom of my post. The root rot is called pythium.

I also have an air rock which provides bubbles in my hydroponics kit and I am wondering if bleach would be ok to use on that or should i get isopropyl alcohol?

Here is a link that might be useful: pythium

I was under the impression that roots didn't like any kind of sunlight to hit them??

That's my observation anyway. The lettuce that germinated when I spilled seeds in the nursery tray... all the ones on the edges, the roots turned black and died, the stuff in the center lived and thrives to this day.

... in other news, i probably should have cleaned it up, but i was curious.

Also: the air rock will be fine with bleach. Bleach doesn't really attack minerals because it's basic. It's only strong acids that would burn the rock, and maby eat at it a bit. And even then, probably only very slightly.