Is the PoolRx pool unit worth it for algae control?

PoolRx isn't a chemical you dose repeatedly, it's a slow-dissolving mineral cartridge, mostly copper and zinc with a bit of silver in the newer formula, sealed inside a perforated plastic case. You set it in the water, usually near the return jet, and the flow keeps gently eroding the minerals over months. Those trace metal ions spread through the pool and make the water inhospitable to algae at a cellular level, so algae struggles to establish itself in the first place instead of you fighting it after it's already green. That's the actual mechanism: it's suppression, not treatment. Because the water is already hostile to algae growth, your chlorine or salt system doesn't have to work as hard to keep things clear, which is where the reduced chemical demand comes from. It works the same way whether your pool runs chlorine, salt, UV or ozone, because it's not reacting with your sanitizer, it's acting on the algae directly. The unit is rated for one pool size band, so putting it in the right gallon range matters more than any dosing schedule you'd normally track.