Loss of PSI

[PuroMexicano]

Hi guys, please help a brother out.

Please see signature for installed equipment.
All my pool piping is 2", except for return fittings, skimmer intake and filter fittings (1.5")

I have 3 pressure side elements:
- Bottom drain
- Skimmer
- Vaccum piping

Normally, while filtering, the bottom drain and skimmer are fully open.
In that instance, PSI is 10 to 11
If I close the skimmer, the drain keeps the PSI around 9-10 and the pump dome is all water filled, but...

If I close the bottom drain valve and let the skimmer alone, pressure drops to 6 PSI and the pump dome is not filled entirely with water
The worst part is the vaccum valve. If I close the skimmer and the bottom drain, pressure drops to 4 PSI and water barely enters the dome.

What are the possible causes asside from piping blockage?

Is the 10PSI pressure a normal pressure for my equipment? based on my filter-pump-piping combination? the pump is about 21 feet apart from the pool.

Thanks for your help!

 

[pooldv]

Pressure in a pool filter is generally the opposite of what people think it is. Lower pressure is good and higher pressure is bad. Lower filter pressure means there is higher water flow to the returns and higher filter pressure means there is lower water flow to the returns. Filter pressure is combination of plumbing restriction, eyeball size, number of 90 degree turns, plumbing size, length, height and dirt in the filter. As pressure goes up it indicates there is more restriction to water flow in the plumbing system.

There is really no normal number. You just need to know clean pressure and then clean the filter when the pressure rises 20-25% above the clean pressure. Pressure at 6-10 psi is certainly fine and we'll within expected pressure readings in a pool.

If the water flow is low from the drain only then it is possible there is a blockage. Normally lack of water flow will result in pump cavitation. Sometimes switching quickly between drain and skimmer will get the blockage moving. Or you can use a drain king or plumber's snake to clear the clockage.

 

[PuroMexicano]

thank you!!