It could be as low as 8, or 10, 12, the pressure could even be lower depending on your filter size, the lower the pressure the cleaner your filter media is the higher the pressure say 17, then you need to back wash or change the media, if you are not using sand.
THE NORMAL GAUGE PRESSURE SHOULD STAY AROUND 12 TO 19 P.S.I
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Clean the Filter!
Input pressure.
What is the normal reading on your pressure gauge? It is a possibility that the gauge itself is broken. Those pressure gauges do not last very long and usually break within the first year. I have found them for as little as $13.00. You may try that first since backwashing was the correct thing to do when the pressure went up.
You may need a new pressure gauge. They are inexpensive and can be found at any place that sells pool products. OR That may be all that you are going to get out of the system you have.
I suppose. Was that the pressure when the filter was new of very clean? No 2 filters will be exactly the same.
Usually the pressure gauge on your pool equipment indicates how much pressure there is before the filter. as the pressure goes up it indicates that the filter is getting blocked and needs a backwash or cleaning. while the pressure is low the filter does not need cleaning.
Your gauge could very well be bad, many pools that we took care of the gauge on the filter was bad, after backwashing the filter just check any of you lines going back to the pool and your should notice the pressure is a lot higher. A lot of people just check the flow by placing there hand at an outlet to check pressure than by walking over too the filter and reading the pressure, instead of buying a new pressure gauge.
This is what your filter gauge will read when it is first start with a new and clean filter cartridge / D.E. or sand.
Around 10 PSI if you have a 2 horsepower pump. It will vary, depending on the restrictions in the exit line. Pool Masters
As the filter gets clogged it restricts the flow of water and the pressure in the return line drops. The pressure gauge on the filter itself indicates the entry pressure and that will go higher as the filter becomes clogged. Don't ever allow the pressure to reach 40 PSI. Back-washing the filter should restore the pressures. Pool Masters