We live in Northern Ohio. where hard freezing is common in the winter.
As a consequence, I disconnet and drain (almost completely) our three
rainbarrels in the winter. But because of sun exposure, algae develops
in the barrels, and is hard to remove and prevent.

The barrels are primarily to irrigate flowers, but also for a strawberry
patch and a squash patch. So a concern is that we don't harm our edibles.

I've read that painting the barrels helps as it keeps the sun out. One
of ours was a grape juice barrel, and is solidly blue, so the sun can't
get in. but two are translucent. I'm disinclined to paint them. as
paint doesn't stick well to plastic, and it's convenient to be able to
see the water level if they are unpainted.

I've read that applications of bleach will control the algae, but the
writers warn to not use the water in the barrel for a few days, when the
chlorine will have dissipated.

Are there other ways to keep the algae from growing and clogging my taps?