Filter pressure keeps jumping up overnight
- Thread starter Silvestor
- Start date
John Faulkner
Member
Might be channeling inside the sand bed. Deep clean the sand with a hose or replace it if it’s older than 5 years.
Kevin Marsh
Member
I had almost the exact same cycle last summer, pressure would be normal in the evening, then by morning it was way up again. What finally helped me figure it out was realizing that not all debris is visible in the water. Even if the pool looks crystal clear, there can be a constant stream of microscopic organics (things like oils, dust, and fine plant matter) that collect in the filter overnight when circulation slows. Once the pump traps them, the pressure shoots up fast.
One thing you might try is giving the filter a good soak in a cleaner that breaks down oils and fine particles. Backwashing alone won’t always remove that gunk. Also, if you haven’t done a full “deep clean” in a while, pulling off the top, running a hose into the sand, and stirring it up until the water runs clear, that can make a huge difference. I did that and suddenly I could go several days without the pressure spiking.
If it still keeps happening, it could just mean the sand is reaching the end of its life and needs changing. Mine lasted about 6 years before it started behaving like that regularly. Replacing it brought everything back to normal.
One thing you might try is giving the filter a good soak in a cleaner that breaks down oils and fine particles. Backwashing alone won’t always remove that gunk. Also, if you haven’t done a full “deep clean” in a while, pulling off the top, running a hose into the sand, and stirring it up until the water runs clear, that can make a huge difference. I did that and suddenly I could go several days without the pressure spiking.
If it still keeps happening, it could just mean the sand is reaching the end of its life and needs changing. Mine lasted about 6 years before it started behaving like that regularly. Replacing it brought everything back to normal.
Lily Allen
Member
I had this happen last season too! It was actually fine debris and organic matter collecting overnight. Even though the pool looked clear, there was still microscopic stuff circulating that was clogging the filter. I ran a clarifier and gave it a good backwash pressure stayed normal after that. Anyone else notice how the filter spikes even when the pool looks clean?
Henry Thompson
Member
I ran into that same overnight spike once, and it turned out to be that the return jets weren’t aimed quite right. The water wasn’t circulating as evenly as it should, so a lot of fine stuff settled into the filter all at once when the pump slowed down overnight.
After I adjusted the jets to push the surface and deeper water around more effectively, the pressure remained a lot steadier. It would be worth a quick check before pulling the filter apart again.
After I adjusted the jets to push the surface and deeper water around more effectively, the pressure remained a lot steadier. It would be worth a quick check before pulling the filter apart again.
Benjamin Tate
Member
Good suggestions already, so I’ll toss in one more angle that caught me out once, pump schedule and when the pressure is actually being read.
If your pump runs longer overnight or switches speeds, the “morning” pressure might not be apples to apples with what you’re seeing in the evening. I had a setup where the pump dropped to low speed late at night, then ramped back up early morning. When it hit high speed again, all the fine junk that settled in the filter overnight got slammed at once and the gauge jumped fast. Looked like the filter magically clogged while I slept, but it was really a flow change revealing it.
Also worth checking the pressure gauge itself. A sticky or waterlogged gauge can creep upward and make it look worse than it is. I swapped mine out on a hunch and realized the spike wasn’t quite as dramatic as I thought, still rising, just not insanely.
One simple test that helped me narrow it down was checking pressure immediately after backwash, then again after a full uninterrupted run at the same speed for a few hours. If it climbs steadily under constant conditions, you’re trapping fines or organics. If it jumps only when speeds change, it’s more of a hydraulics thing than a “dirty pool” issue. Anyone else ever chase a problem that ended up being the gauge lying to them?
If your pump runs longer overnight or switches speeds, the “morning” pressure might not be apples to apples with what you’re seeing in the evening. I had a setup where the pump dropped to low speed late at night, then ramped back up early morning. When it hit high speed again, all the fine junk that settled in the filter overnight got slammed at once and the gauge jumped fast. Looked like the filter magically clogged while I slept, but it was really a flow change revealing it.
Also worth checking the pressure gauge itself. A sticky or waterlogged gauge can creep upward and make it look worse than it is. I swapped mine out on a hunch and realized the spike wasn’t quite as dramatic as I thought, still rising, just not insanely.
One simple test that helped me narrow it down was checking pressure immediately after backwash, then again after a full uninterrupted run at the same speed for a few hours. If it climbs steadily under constant conditions, you’re trapping fines or organics. If it jumps only when speeds change, it’s more of a hydraulics thing than a “dirty pool” issue. Anyone else ever chase a problem that ended up being the gauge lying to them?
Brandon Hayes
Member
A lot of good ground covered already, so I’ll add one more thing to look at that doesn’t get mentioned much.
Do you have any kind of suction-side cleaner or skimmer sock running overnight? I had a similar overnight pressure jump and it turned out the skimmer basket was slowly loading up with really fine debris while the pump was running unattended. By morning the basket wasn’t packed solid, but it was restricted just enough to make the filter pressure read way higher. After a backwash it looked like the filter was the issue, but the restriction was actually upstream.
Another clue for me was that the pump lid had a tiny air bubble in the morning that wasn’t there in the evening. Not enough to cause obvious problems, but enough to mess with flow and pressure readings. Cleaning the skimmer basket nightly and swapping out the sock fixed it. Pressure stopped climbing unless the pool actually got dirty.
Might be worth checking whether anything on the suction side is slowly choking things down while you’re asleep, especially if the water itself still looks perfect. Anyone else notice pressure spikes tied to skimmer loading rather than the filter itself?
Do you have any kind of suction-side cleaner or skimmer sock running overnight? I had a similar overnight pressure jump and it turned out the skimmer basket was slowly loading up with really fine debris while the pump was running unattended. By morning the basket wasn’t packed solid, but it was restricted just enough to make the filter pressure read way higher. After a backwash it looked like the filter was the issue, but the restriction was actually upstream.
Another clue for me was that the pump lid had a tiny air bubble in the morning that wasn’t there in the evening. Not enough to cause obvious problems, but enough to mess with flow and pressure readings. Cleaning the skimmer basket nightly and swapping out the sock fixed it. Pressure stopped climbing unless the pool actually got dirty.
Might be worth checking whether anything on the suction side is slowly choking things down while you’re asleep, especially if the water itself still looks perfect. Anyone else notice pressure spikes tied to skimmer loading rather than the filter itself?