Ryan Brooks
Member
I added sanitizer to my hot tub, but the water still smells funky. I thought chlorine or bromine was supposed to clear that up. What could be causing the bad smell even after treatment?
Why does my hot tub water still smell bad after adding sanitizer?
- Thread starter Ryan Brooks
- Start date
Jake Roberts
Member
A lingering smell usually means there’s a buildup of organic contaminants like body oils, lotions, or bacteria that the sanitizer hasn’t fully broken down yet. I’d recommend doing a shock treatment, which gives the water a bigger boost of sanitizer to clear out the gunk. Also, check your filters if they’re dirty, they can trap bad smells and keep cycling them back into the water.
Benjamin Lewis
Member
Totally get the stinky-hot-tub blues happened to me last summer! 
One trick that worked for me was adding a scoop of non-chlorine shock right before sundown and running the jets on ‘massage’ for 10 minutes. It seemed to wake up the sanitizer and zap that odor right out. Have you tried that timing trick yet?
One trick that worked for me was adding a scoop of non-chlorine shock right before sundown and running the jets on ‘massage’ for 10 minutes. It seemed to wake up the sanitizer and zap that odor right out. Have you tried that timing trick yet?
William Walker
Member
I’ve had that funky smell problem too! Another thing I tried was turning the temperature up a bit for a few hours, which helped the sanitizer break down the contaminants faster. I also added a filter cleaner to help get rid of the buildup that might be trapping the smell. It’s worth experimenting with different combinations!
Amber Chase
Member
Yeah, I’ve run into that too, not fun. 
Even if you’ve added sanitiser, sometimes there’s just too much stuff in the water for it to handle, especially if it’s been a while since the last shock or drain.
One thing that helped me was checking the water balance first (pH and alkalinity), then performing a shock treatment and cleaning the underside of the cover (which I had forgotten to trap smells). You’d be surprised how much odour can build up in the corners and fabric seams. Might be worth a quick check!
Even if you’ve added sanitiser, sometimes there’s just too much stuff in the water for it to handle, especially if it’s been a while since the last shock or drain. One thing that helped me was checking the water balance first (pH and alkalinity), then performing a shock treatment and cleaning the underside of the cover (which I had forgotten to trap smells). You’d be surprised how much odour can build up in the corners and fabric seams. Might be worth a quick check!
David Wilson
Member
I ran into this a few months back and kept throwing more sanitiser in without much improvement, turned out the problem wasn’t just in the water. My circulation cycle wasn’t running long enough each day, so the sanitiser wasn’t getting evenly distributed, and some areas stayed stagnant. After I increased the daily run time and made sure the jets were angled to move water across the whole tub, the smell faded within a day.
Another overlooked culprit can be the plumbing lines themselves. If they haven’t been flushed in a while, biofilm can build up and create that stubborn odour even when the sanitiser level looks fine. Using a line flush product before your next drain-and-refill can help keep that from coming back.
Another overlooked culprit can be the plumbing lines themselves. If they haven’t been flushed in a while, biofilm can build up and create that stubborn odour even when the sanitiser level looks fine. Using a line flush product before your next drain-and-refill can help keep that from coming back.
Katherine Morgan
Member
I ran into something similar once and thought my sanitizer wasn’t working, but the real issue was stale water. Even when the chlorine level was “fine” on the test strip, the tub had been sitting without fresh water for months, and the buildup of dissolved solids was just too high for chemicals to mask the smell. Once I drained, gave the shell a good wipe-down, and refilled with fresh water, the difference was night and day.
If your tub hasn’t been fully changed out in a while, that might be worth trying. Sanitizer can only go so far when the water itself is tired. It’s a bit of effort, but sometimes a reset is the only real cure for stubborn odors.
If your tub hasn’t been fully changed out in a while, that might be worth trying. Sanitizer can only go so far when the water itself is tired. It’s a bit of effort, but sometimes a reset is the only real cure for stubborn odors.
Liam Brooks
Member
I’ve noticed that a bad smell sometimes lingers even when sanitizer levels test okay, and in my case it wasn’t just the water—it was the headrests and cover. They absorb splashes and steam over time, and if you don’t scrub them down regularly, they can hold on to odors that seem like they’re coming from the water.
Another sneaky culprit is trapped foam. If your jets are making a lot of bubbles, that foam can collect residues from soaps, hair products, and even laundry detergents from swimsuits. Scooping it off the surface or using a bit of foam reducer made a bigger difference than I expected.
So if you’ve already shocked, balanced, and cleaned your filters, it might be worth checking those overlooked surfaces and the foam on top.
Another sneaky culprit is trapped foam. If your jets are making a lot of bubbles, that foam can collect residues from soaps, hair products, and even laundry detergents from swimsuits. Scooping it off the surface or using a bit of foam reducer made a bigger difference than I expected.
So if you’ve already shocked, balanced, and cleaned your filters, it might be worth checking those overlooked surfaces and the foam on top.
Mason Blake
Member
If the smell’s hanging around after adding sanitizer, there’s probably stuff in the water that the sanitizer can’t fully break down yet, like oils, lotions, or old residue in the plumbing. I’d give it a shock treatment, clean the filters, and wipe down the underside of the cover (it traps odors more than you’d think). If it’s still funky, it might be time for a drain and refill. Sometimes the water just gets “tired” and no amount of chemicals can fix that.