Pool Filter Installation

Cartridge, sand, or DE: how they compare

All three trap dirt so your sanitizer can do its job, but they do it differently. Sand filters push water through a bed of media and are cleaned by backwashing, which reverses the flow and sends dirty water out a waste line. They are simple and forgiving, but they filter the least finely of the three.

Cartridge filters strain water through pleated fabric and are cleaned by pulling the cartridges and hosing them off. There is no backwash, so no pool water goes down the drain and no waste line is needed. DE filters use grids coated with diatomaceous earth powder and catch the finest particles of all. The tradeoff is handling: you backwash, add fresh DE, wear a mask while you do it, and dispose of spent DE according to local rules.

A large cartridge filter suits a lot of Houston backyards: it keeps pool water out of the waste line, and on weekly pool service the cartridges get rinsed as soon as the gauge calls for it, which matters during oak pollen season. Sand suits owners who want the simplest routine, and DE suits owners who want the clearest water and do not mind more upkeep.

Sizing the filter to the pump

Every filter carries a maximum flow rating in gallons per minute and a filter area in square feet. The filter has to be rated for at least the pump's highest flow, including the speeds you use for spa jets or water features. Going larger than the minimum costs little and pays back all year: more filter area means lower operating pressure and longer stretches between cleanings.

An undersized filter is a common cause of short filter runs, where pressure climbs within days of a cleaning. Local debris makes it worse. Oak tassels and pollen in spring, leaves in fall, and storm debris during hurricane season all reach the filter once they slip past the skimmer and pump baskets. If a new pump is on the list too, choose the two together; our pump installation page covers that side.

Swapping an old filter for a new one

A straight swap keeps the same filter type in about the same footprint, and the main job is lining up the inlet and outlet ports with existing pipes. Changing types takes more work. Moving from sand or DE to cartridge removes the backwash valve and waste line, so the plumbing is reworked and the old waste outlet capped. Moving to sand or DE adds a valve and needs a proper place to send backwash water.

We install with unions where possible so the filter can come off the pad later without cutting pipe, fit a new pressure gauge and air relief valve, and record the clean starting pressure. That number is the reference for every future cleaning. Manufacturers commonly call for cleaning or backwashing at roughly 8 to 10 psi above the clean starting pressure, and your filter's manual sets the exact figure.

Multiport or push-pull valve

Sand and DE filters need a valve to switch between filtering and backwashing. A multiport valve offers several positions, typically filter, backwash, rinse, waste, recirculate, and closed. The waste setting lets you vacuum heavy debris straight out of the pool without loading the filter, which is handy after a storm. A push-pull (slide) valve is simpler, with only filter and backwash, and is common on DE filters.

Which valve you get shapes your routine for years, so it is worth choosing on purpose rather than taking whatever came on the old tank. Whichever you choose, the pump goes off before the handle moves. Cartridge filters skip the valve entirely, which is part of their appeal.

What to expect after the install

In the first days, a new filter can catch fine debris the old one was letting through, so pressure may rise faster than it will later. Freshly plastered pools behave the same way: plaster dust shortens filter runs until it settles out, so expect a few early cleanings after a resurface. Hard water adds its own wear over time, since calcium scale can stiffen cartridge pleats.

After that, cleaning follows the gauge, not the calendar. For routine cleanings, see pool filter cleaning. For leaks, a broken valve, or sand coming back into the pool on a filter you want to keep, see filter repair.

Signs it is time for a new filter

• Pressure climbs back up within days of a cleaning
• A cracked tank or a clamp band that will not seal
• Replacement cartridges or grids for an older model are hard to find
• Repairs keep stacking up on an aging tank
• Cloudy water that stays cloudy even with balanced chemistry
• You upgraded the pump and the old filter is now too small

What we handle

• Cartridge, sand, and DE filter installs
• Like-for-like replacements on existing plumbing
• Converting sand or DE systems to cartridge
• Multiport and push-pull valve replacement
• Pressure gauge and air relief valve setup
• Sizing for pump flow, spa jets, and water features
• Startup with a clean starting pressure on record