Cloudy or milky water can come from poor filtration, low chlorine, high pH, fine debris or water that needs a deeper clean. Start with circulation, filter pressure, chlorine and pH before adding more products.

Start with: pump runtime, filter pressure, free chlorine, pH, recent swimmer load and whether the floor is still visible.

• Quick checks for circulation, filtration and chemistry.
• When clarifier may help and when floc plus vacuuming to waste is more realistic.
• When cloudy water is a reason to keep swimmers out until the water is corrected.

Green water usually needs more than one chemical dose. Start with brushing and filtration, then treat the water and test again so the pool does not turn green again.

Start with: water visibility, wall slime, pump and filter operation, stabiliser level, free chlorine and whether debris is still feeding demand.

• A practical recovery path for green water.
• How to raise chlorine safely for the condition of the water.
• How brushing, circulation and follow-up testing reduce the chance of another bloom.

A strong pool smell is often linked to combined chloramines rather than “too much good chlorine”. Free chlorine, stabiliser, pH and bather load all affect comfort and sanitation.

Start with: free chlorine, combined chlorine, pH, stabiliser/CYA, recent heavy swimming and whether the smell is strongest indoors or near the water surface.

• Why pool smell can mean the water is not being sanitised properly.
• How FC/CYA balance affects family pools and spas.
• When shock treatment should be done carefully to avoid equipment or surface issues.

Brown, black, green or rust-coloured marks need the right identification before treatment. Organic staining and metal staining respond to different tests and products, and some surfaces need extra care.

Start with: stain colour, location, surface type, nearby leaves or metal sources, recent water top-up and whether a small test spot changes the mark.

• Simple spot tests to help identify stain type.
• When ascorbic treatment or a sequesterant may be relevant.
• When stains are cosmetic and when they point to a larger water or surface issue.

Filter pressure is one of the best early signs of a circulation problem. Compare the current reading with your clean-filter baseline before deciding whether the next step is cleaning, valve checking or a service visit.

Start with: clean-filter PSI, pump basket, skimmer basket, return flow, valve positions, cartridge or sand filter condition and suction air leaks.

• How to set and use your own clean-filter baseline.
• Common causes of low pressure and high pressure.
• Different responses for cartridge and sand filters.

Foamy spa water is often linked to soaps, cosmetics, body oils, low calcium hardness or overloaded water. Defoamer may hide the foam for a while, but testing and cleaning usually matter more.

Start with: calcium hardness, sanitiser level, filter condition, recent use, cosmetic products, detergent residue and whether the water is due for a partial drain.

• Common non-chemical causes such as detergents, body oils and cosmetics.
• How water balance and dissolved solids affect foaming.
• When a partial drain and refill is more useful than repeated defoamer.

Low or zero chlorine with a salt system can come from salt level, low water temperature, poor flow, a scaled cell, a tired cell, runtime settings or stabiliser problems. Do not rely only on the chlorinator screen; confirm the result with water testing.

Start with: independent salt test, cell scale, water temperature, flow light, pump runtime, stabiliser/CYA and whether chlorine drops faster than the unit can replace it.

• How to compare the screen reading with an actual salt test.
• When cell cleaning is useful and when it can shorten cell life.
• When low chlorine is really a CYA, runtime or demand problem.

A humming, screeching or dead pump can point to priming problems, air leaks, bearings, a failed capacitor or electrical faults. Some checks are safe for homeowners; other symptoms mean it is better to stop and call.

Start with: water level, pump basket water, lid O-ring, valves, noise type, heat, tripped breaker and whether the pump loses prime after switching off.

• Separate priming and air leak problems from motor or electrical faults.
• Check baskets, valves, water level and obvious suction-side air leaks.
• Stop running the pump if there is heat, burning smell, repeated tripping or no water movement.