Normal pressure for most pools is between 10 and 25 PSI (70-170 kPa). The pressure for filtration systems varies depending on the type of filter, the size of the lines, the pump and other pool equipment.
High swimming pool filter pressure is usually the result of a lot of particles being filtered out of the swimming pool water. When pressure rises it is time to backwash the filter if you have that option with a sand or diatomacesous earth (DE) filter.
Generally, if your pool filter water pressure rises more than 10 PSI over the normal range, it's time to clean – or possibly even replace -- your filter. For most filters, 20 or 30 PSI is considered too high, but you should consult your pool professional to make sure that's true for your model.
Also, seems like you are waiting way too long to clean the filter. We generally recommend cleaning when the pressure goes up 20-25%. So that would would be around 19psi not 30.
A pool filter requires a certain amount of pressure inside the tank to function. If that pressure gets too low or too high, the filter won't work properly, and it can damage other equipment.
The most common reasons why a cartridge, sand, or DE filter's pressure rises quickly, even after cleaning or backwashing, is a clogged or blocked filter, algae or old filter elements. If any of these things are wrong, the pressure can rise rapidly in minutes, hours or days.
Check the Valve
The first thing to do to increase the suction is to check for blockage and air leaks. If one of the skimmers does not suck, it would be necessary to remove the basket from the skimmer. Then check if there isn't a flow control valve at the bottom of the skimmer, which would be almost closed.
The jets should all point in the same direction, ideally at a 45-degree angle that's directed toward the bottom of the pool. One way to remember it: Point the jets at 4 o'clock or 7 o'clock and ensure that the jets are not pushing water toward the skimmers.
After the hose fills with water, backwash your sand filter for 2 - 3 minutes, or until water runs clear. Shut off the pump motor and push the T-handle back down into locked position. Turn your pump back on and note the lower pressure.
It could be a clogged pump basket, impeller, pipe, or skimmer basket. It could also be a closed or broken valve before the pump. In some cases, the pump may have an air leak and is drawing in more air than water. This can reduce filter pressure (and filtration ability).
In most high-rate sand filters, it's time to backwash when the pressure differential reaches 18 to 20 psi. But if the system has only an inlet pressure gauge, you should backwash when the pressure increases by 8- to 10 psi from initial post-backwash readings.
Generally speaking, a pressure reading between 10 – 25 psi can be considered normal. Once you have installed a new filter, turn everything on and take a baseline reading. Each time that you change your pool filter take a new baseline reading.
The best way to position your pool jets is angled slightly downward and all pointing at the same direction or depending on the shape of your pool, that will create one “flow” or circular motion in your pool. The direction should be away from the skimmers.
The level at which pool skimmers function properly is between one third and about half way up the opening of the pool skimmer. If the water level is too high the debris floating next to the opening may pass by without being pulled into the skimmer.
Though returns have traditionally been placed 12 to 18 inches below the water's surface, more professionals are recommending that they be installed closer to the floor.
A skimmer is a necessary element of keeping a pool clean. The skimmer sits at the waterline and catches leaves, bugs and trash so they do not clog the filter. Skimmers with a second hole help keep the pump from running dry if the water level is unstable.
Fill the water up to the proper level with a garden hose. Pool pressure is affected by low water levels. Raise the water level up to the halfway point of the pool skimmer height.
The pressure gauge should read approximately 50 - 70 kpa when the filter is clean. Backwashing is indicated when the pressure exceeds 70 kpa.
Low flow = poor circulation which will lead to algae in the pool. Bottom line, the filter must be backwashed on a regular basis to ensure that your pool water is clear. "When do we need to backwash?" - It is recommended to backwash your filter once every 4-6 weeks of regular use.
A pool filter pressure gauge is the little dial usually located on top of the filter that reads the amount of pressure building up inside your filter. A typical pressure gauge is round, with an indicator needle and a range from 0 PSI (pounds per square inch) to a maximum reading of 60 PSI.
It's best to run your pool pump during the day
Not only does sunlight give fuel for algae to grow, it also destroys your pool chlorine and this is why you should always run your pool during the day!
The pump is losing power.
Over time, older pumps can begin to deteriorate and lose power. In other cases, you might need to clean the filter or have it backwashed.
Look into the clear glass in the strainer lid while the pump is running. If you observe bubbles in the water flowing through the strainer, you probably have a suction leak.