20 Inch Big Blue Carbon Block Cartridge, 3-Pack
Housing two, a year and a half of chlorine-free showers.
Three extruded coconut-shell carbon blocks, 20 by 4.5 inch, 5 micron, for the second housing of the AquaGuard or any Big Blue unit. Carbon saturates without a sign, so the block is the change people put off; three on the shelf mean the six-monthly change happens on the day, three times over.
Why three of the same
A sediment cartridge tells you when it is done: the pressure drops. A carbon block does not. It carries on passing water at full flow long after it has stopped holding chlorine, and the first sign is the swimming-pool smell back in the shower. The only defence is changing it on the date, and the date only gets kept when the next block is already in the cupboard. Three covers a year and a half of that.
When to change it
Every six months, on the date, not on a sign. On heavily chlorinated or smelly supplies, consider the 20 inch GAC in this housing instead, for more contact time.
Before you buy.
Goes with it.
Whole shop
20 Inch Big Blue Carbon Block Cartridge
Housing two. Chlorine out of every shower in the house.
Every 6 months20 Inch Big Blue Cartridge Set
The AquaGuard service, in one box.
20 Inch Big Blue GAC Cartridge
Chlorine and smell at whole-house flow, with more contact time than a block.