The pool filter pressure should be steady, operating in a range of +/- 10 psi. When it's outside this range, very low or very high, then you know that something's wrong. Some gauges allow you to set the clean and dirty range, or you can write it on the filter tank with a marker.
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.
As a general rule, you should be backwashing your pool about once a week or in conjugation with your scheduled maintenance. Another industry standard is to backwash when your filter's pressure gauge reads 8-10 PSI (pounds per square inch) over the starting level or “clean” pressure.
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.
Can You Backwash Too Much? If you backwash your pool too much i.e. time duration and/or close frequency then yes you can cause a lot of problems. Some problems that can arise from backwashing your sand pool filter too much are: Loss of water – 500+ litres of water can be lost in each backwashing cycle.
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.
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.
If the skimmer or pump strainer basket is clogged, the water flow rate will be slower than required. This will lead to low pressure in the pool filter. These baskets get clogged by an accumulation of debris and scum and should be cleaned on a regular basis. A blocked skimmer can cause low or no pressure in the filter.
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.
The lever should be on the 'Filter' setting most of the time. This is the setting that provides normal pool filtration by pushing the water through the filter media (sand, glass beads or D.E) that then traps any dirt and debris before the water is returned to the pool.
Too much sand and your filter will likely not run correctly or may break when reassembling. Too little sand and you will have cloudy water no matter how much your filter runs. For this reason check your filter manufacturer's specs.
If you do not add enough DE to your filter, then the grids are not totally coated with DE and the dirt that goes into your filter will attach itself right to the fabric on the grids and will not backwash off. This will cause your filter to short cycle (go very short times between backwashing).
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.
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 general, you shouldn't be losing sand from your sand filter. Nor should any sand be coming out during backwashing, rinsing or filtering.
A good rule of thumb is to backwash once the pressure displayed on your pressure gauge is 8-10 psi over the starting level. Backwashing after heavy rains, treating for algae, or when trying to clear cloudy water will keep your filter working efficiently.
Turn the lever to RINSE, start the pump and rinse for about 15-30 seconds. Stop the pump and turn the lever to FILTER. This is the normal operating position. Close the drain outlet valve and start the pump.
As a rule of thumb, regardless of if you have a sand filter or DE filter, you should backwash your pool about once a week during swimming season. The optimal time is right after you vacuum the pool. If your pool has had a lot more use than normal, it may be necessary to backwash twice a week.
How Much Sand to Add to Pool Filters? Sand filters are not filled completely full of sand, but only about 2/3 full, to allow “Freeboard” space in the tank, above the sand bed.
Carefully scoop out the sand with a plastic cup. Yes, this can take a long, long, time. Alternatively, you can use a shop vac or a wet and dry vacuum to suck out all of the sand.
You should run your pump/filter as long as it takes to keep the pool clean. Some pools have great circulation combined with low use, therefore run times can be quite short. Other pools have lousy circ systems and huge bather loads and even 24/7 filtration has trouble keeping up.