Does AquaDoc pH Down work slower in hot tubs compared to pools?

syedsam

syedsam

Member
I’ve been using AquaDoc pH Down in my hot tub and it feels like it takes longer to show results compared to when I used it in my pool last summer. I add the amount recommended circulate for 20–30 minutes and the pH only drops a little. Is this normal for hot tubs because of higher temps or am I dosing it wrong?
 
I’ve noticed pH drops slower in a hot tub too. I usually just let the water circulate a bit longer and then it starts to show results.
 
I’ve felt the same thing too sometimes a hot tub just takes a little longer. Try letting it circulate a bit more, and you’ll usually see the results kick in.
 
I’ve noticed pH drops slower in a hot tub too, try letting the water circulate a bit longer, and you'll usually see the results kick in.
 
I've noticed pH drops slower in a hot tub too. I usually let the water circulate a bit longer, and you'll usually see the results kick in.
 
Yeah, that’s pretty normal with hot tubs, and it’s usually not the product or your dosing. Hot tubs behave very differently from pools. The biggest reason is buffering, spas tend to have higher total alkalinity relative to their small water volume, which resists quick pH changes. So even though the pH does move, it can feel sluggish at first.

Another thing working against you is aeration. Jets, bubbles, and high water temperature constantly push carbon dioxide out of the water, which naturally drives pH back up. That doesn’t happen nearly as aggressively in a pool.

What’s worked for me is making smaller adjustments, letting it circulate for a bit longer, then retesting later instead of expecting an immediate drop. AquaDoc pH Down still does its job, it just takes a little patience in a hot tub environment where pH wants to rise all the time.
 
I’ve felt that too, and it’s pretty normal in a hot tub. The water volume is smaller, but TA is often higher, so the pH can be more “buffered” and the drop shows up slower. I usually add a small dose, let it circulate longer, then retest 1–2 hours later (sometimes that’s when it really shows). I wouldn’t rush to add more, because it can keep dropping after and you can overshoot.
 
From what I’ve noticed with hot tubs, pH changes tend to show up slower than in pools. The smaller water volume and higher temperature kind of buffer the reaction, so you don’t always see big movement right away. I usually let it circulate longer and retest a few hours later, that’s when the drop becomes clearer. To me, that behavior is pretty normal for a hot tub setup.
 
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