When a pool stays cloudy, many owners reach for chemicals first. Sometimes chemistry is the problem, but filtration is just as important. A healthy filter removes fine suspended material after brushing, vacuuming and treatment. If it cannot do that, the pool may remain dull even when sanitiser readings look reasonable.
Pool Crew provides pool filter installation and repairs. The guide below helps you interpret pressure, flow and visible symptoms before deciding what needs attention.
Start with the filter’s own normal pressure
There is no single “correct” pressure for every pool because plumbing, pump size, filter type and elevation differ. The useful number is the pressure of your own system when the filter is clean and flow is normal. That becomes the baseline.
If pressure climbs meaningfully above that baseline and return flow weakens, the filter may be loading with debris. Follow the manufacturer’s cleaning or backwash instructions for your filter type.
High pressure with weak flow
This often points to resistance after the pump: a dirty filter, incorrect valve position, blocked return line or restriction in downstream equipment. But a faulty gauge can also lie, so compare the reading with actual return flow.
If the pump itself sounds strained or flow is unstable, read our pool pump warning signs.
Low pressure can also be a problem
Very low filter pressure together with poor return flow can indicate a suction-side restriction, low water level, blocked skimmer/pump basket, air leak, impeller blockage or pump problem. A clean filter cannot compensate for inadequate water reaching it.
Cloudy water after a green-pool treatment
After algae is treated, a large quantity of fine dead material can remain suspended. This is where filtration becomes critical. Brush, vacuum and filter according to the recovery plan, clean or backwash the filter when required, and avoid letting the system become so restricted that flow collapses.
Our green pool after rain and wind guide explains the full recovery sequence.
Sand appearing in the pool
If you have a sand filter and genuine filter media is returning through the jets, damaged laterals or internal components are possibilities. But not every gritty deposit is filter sand. Wind-blown dust and fine garden material can collect on the floor and look very similar.
Check whether the material appears immediately after backwashing or valve operation, and whether it accumulates close to the returns. That information helps narrow the diagnosis.
Multiport valve symptoms
Common warning signs include water leaking from the waste line during normal filtration, a handle that is unusually loose or stiff, or water bypassing the expected flow path. Always switch the pump off before changing multiport positions. Operating the valve while the pump is running can damage the seal.
When filter media needs attention
Sand and other media do not necessarily need replacement just because they are old; condition and performance matter. Channeling, calcification, contamination or repeated clarity problems may justify inspection. The filter should also be correctly sized for the pump and pool.
For replacement equipment, see Pool Crew equipment and chemicals and our provider hub. We work with established suppliers including Quality Pool & Spa Products and Fluidra Waterlinx.
Filtration and water safety are linked
The CDC guidance for operating public pools emphasises maintaining filtration and recirculation systems alongside disinfectant and pH control. The same principle applies at home: clean water requires both treatment and physical removal of contaminants.
When to book a filter inspection
- Pressure repeatedly climbs soon after cleaning.
- Return flow is weak even with clean baskets.
- Water stays cloudy despite appropriate water treatment.
- Media is visibly returning to the pool.
- The tank, valve or unions are leaking.
- The filter and pump appear badly mismatched.
Send equipment photos through Pool Visualiser or contact Pool Crew for an assessment.
Useful external references
Talk to Pool Crew
For weekly, bi-weekly or monthly pool cleaning, a major or once-off clean, green pool recovery, pump or filter work, leak detection or general pool help in Port Elizabeth, speak to our team.