EQUIPMENT
Weak flow from the returns
Read the pressure gauge first: low pressure with weak flow means a blockage before the pump, high pressure with weak flow means a blocked filter.
The pump draws from the skimmer and the main drain, pushes through the filter, and sends the water back out of the returns. The gauge sits after the filter, so what it reads tells you whether the trouble is upstream or downstream of the pump — two completely different problems.
| The gauge reads | Which means | Go and look at |
|---|---|---|
| Below normal, with air in the pump basket | A blockage or an air leak on the suction side — the pump is starved | Skimmer basket, pump basket, water level, and the pump lid O-ring |
| 8–10 psi above the clean reading | The filter is blocked and passing less water | Backwash the filter, then read it again |
| Normal, but the flow is still weak | A valve is throttled, or the return eyeballs are pinched down | Every valve in the line, and the eyeball fittings in the pool |
Work through it
Write down the current gauge reading and compare it with the clean-filter figure.
If you have never noted a clean-filter figure, take one after the next backwash and use it as your reference from then on.
Switch off and clear both baskets, even if they look empty. One wet leaf plastered across the face of a basket halves the flow.
Check the level. If it is below the middle of the skimmer mouth, top it up and look again — the pump is gulping air.
Watch the clear pump lid while it runs. Bubbles circulating constantly mean air is getting in on the suction side.
If you see bubbles, switch off, take the lid off, clean the O-ring, grease it with silicone and hand-tighten the lid back on.
Backwash if the gauge is 8–10 psi over the clean reading, then read it again.
If backwashing does not bring it down at all, the problem is not dirt but the sand bed or the valve itself.
Follow the valves from the pool to the plant room. Someone throttling the main-drain valve and forgetting is common.
Check the return eyeballs in the pool are not turned almost shut.
Related articles
What customers usually read next.
Last updated