Where is a vacuum gauge installed on a circulation system?
- On the suction side, just ahead of the pump
- On the discharge side, just after the pump
- On top of the filter tank at the air relief
- On the return line just before the inlets
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A. On the suction side, just ahead of the pump
A vacuum gauge reads the suction the pump is pulling, so it sits on the suction side near the pump. The discharge side and the filter get pressure gauges.
Reference: PHTA Pool & Spa Operator Handbook, pumps and hydraulics
As a common guideline, when should a sand filter be backwashed?
- When pressure is 8 to 10 psi below the clean starting pressure
- When pressure is 1 to 2 psi above the clean starting pressure
- When pressure reaches the maximum marked on the tank label
- When pressure is 8 to 10 psi above the clean starting pressure
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D. When pressure is 8 to 10 psi above the clean starting pressure
A rise of roughly 8 to 10 psi over the clean reading shows the bed is loaded with dirt, unless the manufacturer says otherwise. Backwashing at a 1 to 2 psi rise wastes water and loses the finer filtration of a slightly dirty bed.
Reference: PHTA Pool & Spa Operator Handbook, filtration chapter
How is a loaded cartridge filter cleaned?
- The flow is reversed to backwash it to waste
- The element is removed and hosed off or soaked
- The element is precoated with fresh filter aid
- The tank is drained and refilled with new media
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B. The element is removed and hosed off or soaked
Cartridge elements are taken out and washed, and often soaked in a cleaner; a spare set keeps the pool running meanwhile. They are not designed to be backwashed.
Reference: PHTA Pool & Spa Operator Handbook, filtration chapter