Replace the mineral cartridge

Nothing visible tells you this is due

A spent mineral cartridge looks exactly like a fresh one, and the water looks fine right up until it does not. This is the single best reason a mineral owner needs a reminder at all.

The interval

Nature2 states 6 months for the M25 and DuoClear cartridges. Replace on the date, not on appearance.

What to do

1. Stop the pump and release system pressure.
2. Open the housing and remove the old cartridge.
3. Fit the new one, close up, restart, and check for leaks.
4. Write the date somewhere you will find it in six months — or let this reminder do it.

Mineral systems are a supplement to sanitiser, not a replacement for it. Keep testing and keep a low chlorine residual.