Raise alkalinity first.

Adjusting pH when alkalinity is low is a waste of time and chemicals. The pH will just bounce around like a ping-pong ball.

Low alkalinity means your water has no buffer. Add acid or base, and the pH swings wildly. Fix this by adding sodium bicarbonate (baking soda) to bring alkalinity up to 80-120 ppm first. Once alkalinity is stable, pH will settle down, and you can fine-tune it with a much smaller dose of acid or base.

Don’t reach for pH Up or pH Down until you’ve checked alkalinity. That’s the cart before the horse.

Pool chemistry isn’t complicated—it just has to happen in the right order.