Reverse osmosis is your only real non-drain option.

It’s expensive — think a few hundred bucks — but it actually removes cyanuric acid without dumping half the pool. A service truck filters your water through a reverse osmosis membrane, stripping out CYA, calcium, and other dissolved solids, then pumps it back.

Everything else is a gimmick. Those “CYA reducers” you see online? Mostly unproven. Bacteria or enzyme treatments might nudge levels down by five or ten ppm, but if you’re at 100+ (which is common), that’s useless. Dilution via rain or topping off is too slow to matter.

Reverse osmosis is the only non-drain method that works. But honestly? For most people, draining a third of the pool and refilling is cheaper and easier. Call around for RO quotes first — if it’s not too crazy, it’s worth it to avoid the water waste and refill time.

Just don’t pour more CYA in. Pool store salespeople will try to sell you stabilizer. You already have too much.