What's going on: Chlorine, salt, chemicals, movement and other exposures gradually break down rubber compounds, causing hardening, cracking and deterioration. Unlubricated orings will grip, stretch and can even tear. Well lubricated orings (with silicone grease, not oils or petroleum), will last longer and seal better. 

You'll know it's time when: Leaking is the biggest obvious tell-tale sign. Visible cracking, flattening, dissolving or loss of the shape. Also, if handling one leaves a black rubber residue on your hand it's time to replace it.

Who can replace: Pump lid and cartridge filter lid can be replaced by the person who cleans these baskets and filters. Other orings are recommended to be replaced by a professional. Always use silicone grease and apply a complete coating to new orings before installation.

What's going on: Silicone handles heat and UV better than standard rubber compounds, but it isn't the most chemical-resistant elastomer available — ongoing chlorine, salt and chemical exposure will still shorten its working life (compared with non-pool applications). In some applications, silicone O-rings have also been known to stretch out of shape in as little as a few months — a dimensional wear issue that's separate from, and can occur earlier than, the chemical hardening/cracking wear described above. Always use silicone grease on orings to reduce this risk.

You'll know it's time when: Cracking, hardening, or leaking at the seal — or visible stretching/loss of original shape, which can show up well before other wear signs.

Who can replace: Pump lid and cartridge filter lid can be replaced by the person who cleans these baskets and filters. Other orings are recommended to be replaced by a professional. Always use silicone grease and apply a complete coating to new orings before installation.

What's going on: The sensing membrane is a consumable element that gradually depletes with continuous exposure to pool chemistry, and fast moving particles in the water. Probes left dry or unmaintained fail noticeably faster than those stored correctly.

You'll know it's time when: Erratic or drifting readings, slow response time, unable to calibrate correctly. Damaged tip is also a clear indicator. If less than 12 months old, clean first using a probe cleaner and tooth brush before considering replacing (sometimes it's just got hair or debris caught on it).

Who can replace: This is a self serviceable part, although they are fragile and can be easily damaged if handled incorrectly.

What's going on: This is one of the most consumable parts in the whole system by design. Full-strength acid can degrade tubing in as little as 3–6 months; diluting acid before dosing (as recommended) meaningfully extends tube life toward the 12-month mark. Only use diluted acid, such as the pre-diluted 15L feeder acid tubs.

You'll know it's time when: Tubing feels stiff, frosted/cloudy, or brittle; visible wear at the pump rollers; reduced dosing accuracy. Collapsed tubing also needs replacing and may signal a blockage somewhere. Always replace the entire feeder tubing from tub to pool pipework, including acid tub pipe and especially the .

Who can replace: Yes, you can replace this but, pool acid is an incredibly dangerous chemical. All precautions must be taken including clothing, eye wear, breathing apparatus, gloves etc. Probably best to get your pool professional to do this one. 

What's going on: Filter media clogs and degrades with normal use. Actual life depends heavily on bather load, environment (dust, pollen, leaf litter), and how consistently the cartridge is hosed down and/or soaked.

You'll know it's time when: Filter pressure stays high even after cleaning, frayed pleats, cracked end caps, reduced flow. Low flow through your chlorinator cell, or a fresh wash only provides a short relief to reduced flow/high pressure.

Who can replace: You can do this one. Next time it's out for a clean, just put your new one in instead.

What's going on: The titanium electrode plates wear through continuous electrolysis (what makes them work). Add this to the fast moving water particles and this gradual wear brings the expected end of a cell's working life — it's why cells are a scheduled replacement item rather than a one-off purchase.

You'll know it's time when: Declining chlorine output, despite correct salt levels, increasing run-time needed to maintain sanitiser, visible plate wear on inspection.

Who can replace: You can replace this, although it can be a hard one to do. If you're struggling, rather than risk damage anything, give your pool professional a call.