Pentek FloPlus-20BB 0.5 micron filter cartridge - Big Blue

Pentek FloPlus-20BB filter cartridge

Block carbon filter cartridge in Big Blue 20" × 4.5" format, filtration rating 0.5 micron, built around Pentair's modified Fibredyne media. Manufacturer reference 455906-43.

Service flow rate 4 gpm (approximately 15 L/min) for a pressure drop of only 4 psi. Stated capacity of over 50,000 gallons (approximately 190,000 litres) for chlorine reduction at this flow rate.

The problem this cartridge solves

On a standard carbon cartridge, fineness and flow rate are in direct opposition.

A 0.5 micron block carbon offers advanced mechanical filtration, but at the cost of high pressure drop. On a main water line, this results in pressure falling as soon as two draw-off points operate together. Many installations abandon 0.5 µm for this reason alone and settle for a more open rating.

The FloPlus is designed to eliminate this trade-off.

Modified Fibredyne media

Fibredyne is Pentair's carbonated block technology. The modified version used here operates the media in depth filtration rather than surface filtration.

The result is the central point of this product: a 0.5 micron rating with flow rates and pressure drop comparable to a nominal 10 micron cartridge. Four psi pressure drop at 4 gpm is the level of a sediment pre-filter, not a fine block.

In practical terms, this makes 0.5 µm installable where it was not before: main water line of a dwelling, small multi-unit building, professional draw-off point with sustained flow.

What the cartridge treats

Chlorine, tastes and odours. This is the work of activated carbon, by adsorption. The stated capacity of over 50,000 gallons places this cartridge well above a standard block on this criterion.

Particles down to 0.5 micron, by depth mechanical filtration.

Cysts. Pentair claims NSF/ANSI 53 certification for this range covering the reduction of Cryptosporidium and Giardia cysts to 99.95 %. This is a strong selling point on installations fed by borehole, well or rural network, and it is based on a standardised test, not a commercial claim.

The Big Blue 20" format

The 20" × 4.5" is the large format in cartridge housing filtration: large media volume, therefore long contact time and high autonomy.

This is the format consistent with this product. A fine block in 10" would see its capacity exhausted much faster, and the benefit of modified Fibredyne on flow rate makes full sense on a device placed at the head of an installation.

Where to use it

As head-of-line treatment on a main water line, when you want both taste improvement and fine filtration without restricting pressure. As protection for a reverse osmosis unit or treatment chain. On professional installations with sustained flow. And on networks where cyst issues arise: wells, boreholes, rural distribution.

On water heavily loaded with sediments, provide a pre-filter upstream, typically 20 or 25 µm then 5 µm. Even with media designed for flow, a 0.5 µm block that takes on all the particulate load alone will clog mechanically well before exhausting its adsorption capacity.

Replacement

Two mechanisms limit service life, and whichever occurs first applies.

Carbon saturation. The media fills up, and once full it retains nothing more. The signal is the return of chlorine taste or odour.

Mechanical clogging. At 0.5 µm, this is read on the pressure drop: an upstream/downstream differential that rises, or a noticeable drop in flow rate.

The stated capacity of 50,000 gallons is a laboratory value for chlorine reduction. In practice, on real water, it is often clogging that occurs first. Monitoring pressure drop remains the reliable method.

Installation

Cut off the water and depressurise before opening the cartridge housing. Respect the direction of flow.

The bowl of a Big Blue 20" filled with water is heavy: provide a properly fixed wall bracket and sufficient clearance under the bowl to lower it.

On reassembly, grease the O-ring with food-grade silicone grease and check that it is clean and properly seated. This is the leading cause of leaks on a cartridge housing, and the issue is proportional to the size of the bowl.

After water is restored, rinse for several minutes before use: all new carbon releases black fines at start-up.