I know where your coming from!
I got confused as to what to buy.
I wasn't keen on anything that would contain bleach, as a customer had a wall cleaned by a company & the bleach had stripped the garage door paint.
I ended up buying AlgoClear Pro and trialing it on a mates house, I had broken ribs when I did it about 10wk ago, & thought I would need to return to wash over again.
When I mentioned I would be calling later that week to give another go over, he sent me a picture showing it as all gone, saying no need.
I was there last week end & the walls looked liked they had been repainted. We are both more than impressed.
The result it has given me the confidence to be able to sell as an add on service.
So while I can't speak of having broad knowledge on the subject or chemicals, I can vouch for this particular treatment.
Still in a learning curve, esp when it comes to pricing in this area.
pic is before & just after treatment. No algae at all left after as it kills the root...