Question 1

Which cartridges fit my reverse osmosis system?

Accepted Answer

Nearly every five and six stage under-sink RO sold in South Africa uses standard 10 by 2.5 inch cartridges and the 1812 membrane. If the cartridge you are replacing is about 25 cm long and 6.5 cm across, the 10 inch sediment, GAC and carbon block here fit it, whatever the brand on the housing.

Question 2

Which cartridges fit a 20 inch Big Blue housing?

Accepted Answer

Big Blue is a standard: 20 inches long, 4.5 inches across, whoever moulded the housing. The 5 micron sediment, carbon block, GAC, 1 micron and refillable shell here fit the AquaGuard and any other Big Blue unit.

Question 3

How often should I change them?

Accepted Answer

Sediment and carbon stages every six months on municipal water, sooner on a borehole or tank. The post-carbon and re-mineraliser once a year. The RO membrane every two to three years. A pressure gauge either side of a whole-house unit shows the moment: 0.7 bar of difference means the cartridges are full.

Question 4

Sediment first, then carbon, then what?

Accepted Answer

Coarse to fine. In a Big Blue unit: 5 micron sediment, then carbon block, then 1 micron sediment. In an RO: sediment, GAC, carbon block, then the membrane, the post-carbon and the re-mineraliser. Carbon put first loads with grit and saturates early.

Question 5

Carbon block or GAC?

Accepted Answer

A carbon block is pressed carbon with its own 5 micron rating, so it filters as well as adsorbing: the right choice for most municipal supplies. Granular carbon (GAC) gives more contact time for heavily chlorinated or smelly water. Both fit the same housing.

Question 6

What is the difference between 5 micron and 1 micron?

Accepted Answer

The size of particle the cartridge stops. Five micron catches sand, rust and silt and goes first; one micron catches the fine silt and most cysts and goes last. A 1 micron stage is what a UV steriliser needs ahead of it.

Question 7

Are they in stock?

Accepted Answer

They are stocked in Randburg and paid orders leave within 24 hours; a listing says so when one is out. The 3-packs and the two-set box put the next change on the shelf, which is how the six-month change happens on the day.

Replacement Cartridges

AquaShield RO filters, 10 inch

RO Pre-Filter Kit, 6 Month

RO Full Service Kit, 6 Stage

10 Inch Sediment Filter, 5 Micron

10 Inch GAC Filter

10 Inch Carbon Block Filter, 5 Micron

75 GPD RO Membrane, 1812

Inline Post-Carbon Filter

4-in-1 Re-Mineraliser Cartridge

20 inch Big Blue cartridges

20 Inch Big Blue Cartridge Set

20 Inch Big Blue Cartridge Set, Two Sets

20 Inch Big Blue Sediment Cartridge, 5 Micron

20 Inch Big Blue Sediment Cartridge, 5 Micron, 3-Pack

20 Inch Big Blue Carbon Block Cartridge

20 Inch Big Blue Carbon Block Cartridge, 3-Pack

20 Inch Big Blue Sediment Cartridge, 1 Micron

20 Inch Big Blue Sediment Cartridge, 1 Micron, 3-Pack

20 Inch Big Blue GAC Cartridge

20 Inch Refillable Cartridge Shell

Read before you buy.

How often should you change water filter cartridges in South Africa?

Which replacement cartridges fit my RO system? The 10 inch standard explained

How to change the filters on a reverse osmosis system, in fifteen minutes

Before you choose.