pH keeps dropping even after using increaser
- Thread starter Manikshaw
- Start date
John Faulkner
Member
I had the same issue when I was using trichlor tablets they slowly lower pH over time switching to liquid chlorine stopped the constant drop.
George Kelly
Member
I’ve run into that before, and it can be a bit of a guessing game. Even if alkalinity tests look okay, sometimes it’s on the lower end and doesn’t buffer the pH very well, so it keeps drifting down. Another thing that pushes pH lower is high aeration, if you’ve got waterfalls, spa jets, or even just a lot of splashing, the CO₂ leaving the water makes it drop faster.
What helped me was keeping an eye on both TA and pH together instead of treating them separately, and switching up my chlorine source like John mentioned. Liquid chlorine tends to be more pH-neutral compared to tablets. Once I balanced the TA a little higher and cut back on tablet use, the pH finally held steady instead of sliding down every few days.
What helped me was keeping an eye on both TA and pH together instead of treating them separately, and switching up my chlorine source like John mentioned. Liquid chlorine tends to be more pH-neutral compared to tablets. Once I balanced the TA a little higher and cut back on tablet use, the pH finally held steady instead of sliding down every few days.
Katherine Morgan
Member
I had the same head-scratcher a while back, and it turned out there were a couple of sneaky things at play. One was filled with water, while mine comes out of the tap slightly acidic, so that every top-off would drag the pH down again. The other was chlorine demand. When the pool was fighting off a lot of organics, the constant dosing seemed to lower the levels faster than usual.
What finally made a difference was testing the source water and treating it before it entered, plus administering a larger shock to get ahead of what was depleting the chlorine. After that, the pH increaser actually stayed in place instead of sliding back down within a couple of days.
What finally made a difference was testing the source water and treating it before it entered, plus administering a larger shock to get ahead of what was depleting the chlorine. After that, the pH increaser actually stayed in place instead of sliding back down within a couple of days.
Amber Chase
Member
I’ve had the same struggle, and in my case it turned out the total alkalinity wasn’t quite high enough, even though it looked “okay” on the test. Once I brought TA up a bit more, the pH stopped swinging so much. I also noticed that when I ran water features a lot, the extra aeration made the pH fall faster. Might be worth checking both things together instead of just chasing pH on its own.
Andrew Coleman
Member
I had that same issue where pH just wouldn’t stay up, and it turned out to be a combo of things. My fill water leaned acidic, so every top-off dragged it down, and I was also using trichlor tabs which kept pushing it lower. Once I tested my source water and switched over to liquid chlorine, the problem pretty much disappeared.
Might be worth checking both the water you’re adding and your chlorine type, sometimes it’s not the increaser at all, but those underlying factors that keep fighting against you.
Might be worth checking both the water you’re adding and your chlorine type, sometimes it’s not the increaser at all, but those underlying factors that keep fighting against you.
Henry Graham
Member
I’ve battled that same problem before, and in my case the culprit wasn’t obvious at first. Even though TA looked “normal,” it wasn’t giving the pH enough stability, so it kept sliding back down. On top of that, I later found out my auto-feeder with tablets was slowly pushing it lower every day.
What finally helped was bumping TA up a touch higher than the bare minimum and cutting back on tablet use in favor of liquid chlorine. Since then, the pH holds steady a lot longer instead of crashing every few days.
What finally helped was bumping TA up a touch higher than the bare minimum and cutting back on tablet use in favor of liquid chlorine. Since then, the pH holds steady a lot longer instead of crashing every few days.
Henry Graham
Member
One thing I didn’t see mentioned yet is surface chemistry and testing accuracy. If the pool is newer (or recently resurfaced), plaster and cement-based finishes can quietly pull pH down for months while they finish curing. It’s slow and annoying, but increaser just gets consumed until things settle out.
Another angle is the test itself. Old reagents, strips stored in heat, or inconsistent water temp can make pH look lower than it really is, which leads to overdosing and the feeling that nothing “sticks.” Swapping to a fresh drop kit cleared that up for me.
Also worth checking if you’re using borates or a product that contains them. They can flatten pH movement, but if they’re low or uneven, the pH can drift faster than expected.
If none of those apply, try raising pH more gradually over several days instead of one bigger correction. Sometimes slow adjustments hold better than forcing it upward all at once.
Another angle is the test itself. Old reagents, strips stored in heat, or inconsistent water temp can make pH look lower than it really is, which leads to overdosing and the feeling that nothing “sticks.” Swapping to a fresh drop kit cleared that up for me.
Also worth checking if you’re using borates or a product that contains them. They can flatten pH movement, but if they’re low or uneven, the pH can drift faster than expected.
If none of those apply, try raising pH more gradually over several days instead of one bigger correction. Sometimes slow adjustments hold better than forcing it upward all at once.
Ionut Kaminski
Member
I’ve dealt with this too. If you’re using chlorine tablets, they often slowly pull pH down, especially after rain or after adding fresh water. Try checking the pH of your tap water, and if you’re on tablets, switch to liquid chlorine for a bit. That usually helps the pH stay steadier so you’re not adding pH increaser all the time.
John Harrison
Member
I fought this for almost a full month and it drove me crazy because on paper everything “looked fine.”
In my case alkalinity wasn’t low, but it also wasn’t really buffering well. It was sitting around 70 and I kept focusing only on pH. I’d bump pH up to 7.6, feel good about it, then 48 hours later it was back at 7.2. What I didn’t realize was I was feeding the drop with trichlor tabs in a floater. Those things are acidic. Every day they dissolve a little and quietly pull pH down.
Another thing that surprised me was chlorine demand. When my pool was fighting off low level organics, the oxidation process seemed to drag pH down with it. Once I got past that demand hump and cleaned the cartridge filter, the drop slowed way down. Filter pressure had been creeping up 3 to 4 psi and I ignored it.
A couple things I’d check:
– Are you using tabs regularly
– Has there been a lot of rain or top off water
– Is TA on the low end of “normal”
– Is your filter dirty or chlorine demand high
When I switched to liquid chlorine for a while and nudged TA closer to 80 to 90, pH finally stopped sliding. I also stopped making big jumps with increaser and started doing smaller corrections. For whatever reason, gradual adjustments held better.
If alkalinity truly is solid and you’re not using acidic sanitizer, I’d test your fill water too. Sometimes the pool isn’t the problem, it’s what you’re adding to it. Once you remove the thing pulling it down, pH increaser actually sticks instead of feeling like you’re pouring it into a black hole.
In my case alkalinity wasn’t low, but it also wasn’t really buffering well. It was sitting around 70 and I kept focusing only on pH. I’d bump pH up to 7.6, feel good about it, then 48 hours later it was back at 7.2. What I didn’t realize was I was feeding the drop with trichlor tabs in a floater. Those things are acidic. Every day they dissolve a little and quietly pull pH down.
Another thing that surprised me was chlorine demand. When my pool was fighting off low level organics, the oxidation process seemed to drag pH down with it. Once I got past that demand hump and cleaned the cartridge filter, the drop slowed way down. Filter pressure had been creeping up 3 to 4 psi and I ignored it.
A couple things I’d check:
– Are you using tabs regularly
– Has there been a lot of rain or top off water
– Is TA on the low end of “normal”
– Is your filter dirty or chlorine demand high
When I switched to liquid chlorine for a while and nudged TA closer to 80 to 90, pH finally stopped sliding. I also stopped making big jumps with increaser and started doing smaller corrections. For whatever reason, gradual adjustments held better.
If alkalinity truly is solid and you’re not using acidic sanitizer, I’d test your fill water too. Sometimes the pool isn’t the problem, it’s what you’re adding to it. Once you remove the thing pulling it down, pH increaser actually sticks instead of feeling like you’re pouring it into a black hole.
Robert Smith
Member
I ran into this last season and it was a total pain for a few weeks. My pH would look good right after adjusting, like around 7.5, then two days later it would slide back to the low 7s again. TA looked “fine” on paper too so I kept thinking the increaser just wasnt doing anything.
What I eventually noticed was my pool was getting a steady stream of acidic inputs without me realizing it. Between a few rainstorms and topping off the pool, the fresh water coming in was slightly acidic. On top of that my pump had been running longer because we had people over a lot, so the bather load and organics were higher than normal. That combo seemed to chew through the pH buffer faster than I expected.
The thing that helped most was slowing down the corrections and watching the pattern instead of trying to force it up in one go. I’d bring pH up a little, let the pump circulate half a day, then test again the next morning. Also checked my filter pressure since poor circulation can make readings look weird. Once the water settled and the extra demand dropped off, the pH finally started holding for a week or more instead of sliding every couple days. Anyone else notice their pH gets way more stubborn during heavy pool use weeks?
What I eventually noticed was my pool was getting a steady stream of acidic inputs without me realizing it. Between a few rainstorms and topping off the pool, the fresh water coming in was slightly acidic. On top of that my pump had been running longer because we had people over a lot, so the bather load and organics were higher than normal. That combo seemed to chew through the pH buffer faster than I expected.
The thing that helped most was slowing down the corrections and watching the pattern instead of trying to force it up in one go. I’d bring pH up a little, let the pump circulate half a day, then test again the next morning. Also checked my filter pressure since poor circulation can make readings look weird. Once the water settled and the extra demand dropped off, the pH finally started holding for a week or more instead of sliding every couple days. Anyone else notice their pH gets way more stubborn during heavy pool use weeks?
Megan Lawson
Member
I ran into this exact pattern a couple seasons ago and it drove me nuts for a while because every adjustment looked good for a day or two, then the pH would slide right back down again.
In my case the issue wasn’t the increaser, it was that something in the system kept quietly pushing the pH lower. For me it was a mix of acidic sanitizer and a bit of chlorine demand at the same time. Even though alkalinity was technically in range, it was sitting on the lower side and didn’t buffer the drop very well. So every time I raised pH to around 7.5 or 7.6, it would slowly drift back toward the low 7s within a couple days.
One thing that helped was stepping back and looking at the bigger picture instead of just correcting pH. I checked my sanitizer type, cleaned the filter so circulation was strong again, and nudged alkalinity slightly higher so it could stabilize the water better. I also started making smaller pH adjustments instead of big jumps.
Another small thing worth checking is your fill water. If you’re topping off the pool fairly often and that source water has a lower pH, it can quietly drag the pool down over time. I didn’t realize that was happening in my case until I tested the hose water separately.
Once the underlying cause stopped pulling the pH down, the increaser finally started holding and I wasn’t adjusting it every couple of days anymore.
In my case the issue wasn’t the increaser, it was that something in the system kept quietly pushing the pH lower. For me it was a mix of acidic sanitizer and a bit of chlorine demand at the same time. Even though alkalinity was technically in range, it was sitting on the lower side and didn’t buffer the drop very well. So every time I raised pH to around 7.5 or 7.6, it would slowly drift back toward the low 7s within a couple days.
One thing that helped was stepping back and looking at the bigger picture instead of just correcting pH. I checked my sanitizer type, cleaned the filter so circulation was strong again, and nudged alkalinity slightly higher so it could stabilize the water better. I also started making smaller pH adjustments instead of big jumps.
Another small thing worth checking is your fill water. If you’re topping off the pool fairly often and that source water has a lower pH, it can quietly drag the pool down over time. I didn’t realize that was happening in my case until I tested the hose water separately.
Once the underlying cause stopped pulling the pH down, the increaser finally started holding and I wasn’t adjusting it every couple of days anymore.
Nathan Parker
Member
I had a stretch like this a couple summers ago and it drove me nuts because the numbers looked fine at first glance. I’d bump the pH to around 7.6, test again two days later and it was sliding back into the low 7s again. TA was sitting around the mid 70s so technically “in range”, but the water just didn’t seem to have much buffering strength.
What finally clicked for me was realizing how much CO2 loss and circulation patterns were affecting things. My returns were pointed up and the pool was getting a lot of surface agitation, plus the pump was running long cycles during hot weather. That constant aeration changes the carbonic balance in the water and the pH response can get weird, especially if alkalinity is just barely above the alkalinity floor. Once I nudged TA closer to about 85 and aimed the returns slightly downward to calm the surface a bit, the pH stopped drifting every couple days.
Also worth glancing at your filter pressure if you haven’t lately. When my cartridge started loading up with fine debris the pressure climbed about 5 psi over the clean baseline and circulation got uneven. After I rinsed it and the flow improved, the chemistry stabilized way more than I expected. Sometimes it’s not the increaser at all, it’s just the water not mixing evenly. Anyone else see pH act strange when the filter starts getting a little gunked up?
What finally clicked for me was realizing how much CO2 loss and circulation patterns were affecting things. My returns were pointed up and the pool was getting a lot of surface agitation, plus the pump was running long cycles during hot weather. That constant aeration changes the carbonic balance in the water and the pH response can get weird, especially if alkalinity is just barely above the alkalinity floor. Once I nudged TA closer to about 85 and aimed the returns slightly downward to calm the surface a bit, the pH stopped drifting every couple days.
Also worth glancing at your filter pressure if you haven’t lately. When my cartridge started loading up with fine debris the pressure climbed about 5 psi over the clean baseline and circulation got uneven. After I rinsed it and the flow improved, the chemistry stabilized way more than I expected. Sometimes it’s not the increaser at all, it’s just the water not mixing evenly. Anyone else see pH act strange when the filter starts getting a little gunked up?