I am going to be installing a pump for bleach injection and possibly a 2nd pump for MA injection. They would not be injecting at the same time, the MA only when needed. Where would be the best place for injection be? at the pump drain or in the pool return line? I just want to make sure the either the bleach or the MA will not damage any parts if installed at the pump valve (ie pump basket, filter gaskets, etc...) or will it be diluted enough to not have to worry about it??? I am going to install a "T" for the 2 separate injection valves.

The best place is in the return after all other equipment. However, you can place the bleach injection point about anywhere and it'll be fine. I wouldn't inject acid before the equipment. It may be fine but why take the chance?

That's kinda what I was thinking, just wanted a little confirmation.