MB400 DI - Mixed Bed Deionising Resin - Smaller Packs for Refillable cartridges

This is MB400 mixed bed deionising resin, sold by WrekinWater as a refill charge for the Wrekin DI Refillable Cartridge range (the cartridge itself is sold separately). Mixed bed resin combines cation and anion exchange beads in one blend so it strips out dissolved minerals in a single pass, which is why it's popular for spot-free car washing and detailing rinses. It's available in 1L, 5L and 10L packs to match different cartridge sizes.

Signs you need to top up/replace this

• Your rinse water TDS reading starts climbing instead of sitting near zero.
• The resin's colour has changed from its fresh colour toward amber or brown.
• Water spots reappear on paintwork after using your usual DI rinse.
• The cartridge output slows noticeably compared to when the resin was fresh.

Mixed bed resin works by mixing cation and anion exchange beads together so that as water passes through, both positively and negatively charged dissolved ions are removed at the same time, leaving deionised, spot-free water. Each bead in the mix has a finite exchange capacity, and once it's used up the resin can no longer swap out ions, letting dissolved minerals pass straight through to your rinse water and causing water spotting again, even though the cartridge is still full and looks the same as ever from the outside.

WrekinWater is a family run water treatment specialist based in Bettisfield, Shropshire, with over 50,000 customers served across 15 years. This is the same resin used to refill our own Wrekin DI Refillable Cartridge range, so you're getting a charge matched to the housing rather than a generic substitute.

How to top up / replace it

1. Unscrew the cartridge's end cap.
2. Empty out the old, exhausted resin.
3. Rinse the housing out before refilling.
4. Pour in the correct pack size of fresh MB400 resin for your cartridge's fill volume.
5. Refit the diffuser/pad and end cap securely.
6. Flush the cartridge briefly before use to clear any loose fines.