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.
Your filter may be clean and normal at 9-10 psi, but your neighbor's filter gauge could run higher, and be clean at 15-16 psi. Some systems with very low resistance can run very low pressures, barely registering, while other filter systems can run quite high, pushing 30 psi when the filter becomes dirty.
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.
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.
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.
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.
On average, a pool filter cartridge's pressure reading, in PSI on the filter gauge, should read between 8 – 15 PSI. If you are experiencing an 8-10 PSI increase in pressure, somewhere up around 25-30 PSI or higher, this means that it is time for you to clean your filter!
The pressure gauge should read approximately 50 - 70 kpa when the filter is clean. Backwashing is indicated when the pressure exceeds 70 kpa.
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.
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.
Adding too much DE to your pool may cause multiple negative results. These ramifications include a clogged skimmer, turning the pool cloudy, reducing the circulatory pressure in the pool and putting too much work on your pump that may result in eventually breaking the pump.
When you first install a sand filter or renew the sand, you may indeed get a small amount of sand coming out when backwashing, rinsing or filtering. Often, excess sand gets into the wrong places when refilling and will sand to come out into the pool or out of the backwash hose. But it should go away after a few runs.
In order to prevent residual blow back into the pool, once you've finished backwashing it's highly advisable to rinse the filter. Just as the backwash lifts and flushes the sand, the rinse resets the sand to its original position for optimum filtration.
* Can i discharge the backwash water onto my lawn, will it harm the grass / plants? The DE doesn't harm the grass or plants, excessive chlorine or saltwater may.
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.
It's good practice to point your return jets in a direction that will circulate the water in your pool. If your pool only has one jet, point the jet toward the skimmer and downward. This will circulate the water, and push the water at the bottom of the pool to the surface.
Add diatomaceous earth (DE) to your pool skimmer, stick to around a scoop or two – no more than the size of a 1lb coffee cup. The moment you do this, go to the pool jets to see if it is returning DE into the pool, or if the water suddenly looks cloudy. If it is, you likely have an issue with your filter.
The size of your pool, the efficiency of your pump and filter, and how dirty your pool is are just some of the factors you need to consider. Nevertheless, most pool cleaning professionals would advise against running a pool pump for more than 8 hours a day.
It could be something blocking it, a dirty pool filter, or too much air in the system. If there's something blocking your pump's suction, check your filter gauge. If it's 10psi above the normal reading, clean your filter. This will reduce pressure and reset your pump's flow.