for New Equipment Installation - Residential homeowners within service area
Ask About
Energy-Saving Variable Speed Pool Pumps
Pool Owner’s Guide · Your Equipment
Pool Filters: Sand, Cartridge and DE Explained
by Spectrum Pool Care
Clean water and clear water aren’t quite the same thing. Chlorine keeps water clean; the filter is what makes it clear. Here’s how the three kinds of pool filter do it.
Chlorine keeps pool water clean, free of germs and algae. But water can be perfectly sanitized and still look a little dull, because tiny particles of dust, pollen and minerals are floating in it. Catching those is the filter’s job, and it’s what turns clean water into clear water.
Filters are measured by the smallest particle they catch, in microns. A micron is a thousandth of a millimeter; a human hair is about 70 microns across, and most people can’t see anything smaller than about 40.
Three Kinds
Sand, Cartridge and DE
Sand · about 20 – 40 microns
Water trickles down through a bed of special filter sand. Simple and long-lasting. It’s cleaned by backwashing, running water backward through the sand to rinse it.
Cartridge · about 10 – 20 microns
Water passes through pleated fabric, much like a giant air filter. The cartridges are taken out and hosed clean, then replaced every few years.
DE · about 3 – 5 microns
The finest of the three. Fabric grids are coated with diatomaceous earth, which forms a very fine screen. After cleaning, fresh DE is added.
A word about DE
DE is made from the fossil shells of diatoms, single-celled algae with glassy, lace-like walls. Ancient water life, helping keep today’s water clear.
Getting to Know Yours
Reading the Pressure Gauge
Every filter has a small pressure gauge on top, and it’s the easiest way to know how your filter is doing.
Find your baseline. Right after a cleaning, note the reading. That’s your filter’s “clean” number.
Watch it climb. As the filter catches more, the pressure slowly rises.
8 – 10 psi above baseline is the usual sign it’s ready for a cleaning.
A little dirt helps. A slightly used filter actually catches finer particles than a perfectly clean one, so there’s no need to clean it too often.
From our routes: filters work hardest after storms, windy weeks and a busy swim season. When we notice a filter needs attention, we’ll let you know. And if you notice the water isn’t as clear as usual, give us a call and we’ll set up a filter cleaning or repair visit.
