📌 Key Takeaway: Choosing between cartridge, DE, and sand filters comes down to balancing filtration fineness, labor time per stop, and parts cost across the accounts on your route.
Filtration is one of the few topics where the right answer changes based on who is paying for it: the homeowner, your service business, or both. As a route owner, the filter type on each pool dictates how long a stop takes, how often you carry parts, and how often you get callbacks for cloudy water. This breakdown walks through the three dominant systems with a service tech's perspective, not a retail one.
Cartridge Filters On A Service Route
Cartridge filters are the workhorse of newer suburban pools, especially in the Sun Belt where backwash water restrictions matter. From a route standpoint, they are friendly because the typical weekly stop involves nothing more than glancing at the pressure gauge. No backwash valve to fight with, no DE powder to mix, no slurry to dump.
The real labor shows up two to four times a year during a teardown. You pull the lid, lift two to four cartridges, hose them down, and inspect the bands and end caps. Plan on 20 to 30 minutes per pool for a proper cleaning, plus drive time if you make a separate trip. Smart route operators batch cartridge cleanings by neighborhood on a dedicated day rather than absorbing the time into a regular service stop.
Where cartridges hurt margins is replacement cost. A full set of OEM cartridges for a 420 to 520 square foot unit can run $200 to $450, and homeowners are often shocked the first time. Build replacement intervals into your service agreement so the conversation happens before the cartridge looks like a chewed-up sponge. Generic cartridges save money up front but fail sooner, which means more callbacks for pressure issues.
DE Filters And The Hidden Time Cost
Diatomaceous earth filters produce the clearest water of the three, filtering down to roughly 3 to 5 microns. For green-to-clean recoveries and pools with heavy organic load, they are unbeatable. But on a recurring route, DE filters consume more of your weekly time than any other piece of equipment.
A standard bump-and-backwash cycle takes 10 to 15 minutes once you account for running the cycle, waiting for waste to clear, recharging with DE powder through the skimmer, and verifying pressure returns to baseline. Multiply that by every DE pool on your route and the math gets uncomfortable fast. Most efficient operators only fully backwash DE filters monthly or when pressure rises 8 to 10 psi above clean, not weekly.
Teardowns are where DE filters really demand attention. Grid filters need annual disassembly to inspect for tears, manifold cracks, and calcium buildup. A torn grid sends DE back into the pool through the returns, which means an emergency call. Carry spare grids and manifold O-rings in your truck if you service more than a handful of DE units. When evaluating pool routes for sale, check what percentage of stops are DE versus cartridge before signing, because a DE-heavy route demands either higher pricing or fewer stops per day.
Sand Filters: Simple But Coarse
Sand filters are the legacy option, still common on older inground pools and most above-ground installations. The filtration ceiling sits around 20 to 40 microns, which means visible particulate clears fine but fine algae and dead-cell debris often pass straight through. For pools with heavy bather load or persistent algae issues, you will fight clarity battles all summer.
Operationally, sand is the easiest filter type to maintain on a weekly basis. Backwashing takes five minutes, the media lasts five to seven years before needing replacement, and there are very few moving parts that fail. The multiport valve is the main wear item, and a $40 spider gasket fixes most leaks. For budget-conscious accounts and rental properties, sand filters keep your service costs predictable.
The catch for route operators is selling clarity-sensitive customers on what sand can actually deliver. If a homeowner expects gin-clear water in a pool with a sand filter, a heavy oak tree overhead, and three kids who swim daily, you will lose that account. Set expectations during the first visit, or recommend a flocculant routine, or upsell them to a cartridge swap.
Cost Comparison Across A Full Route
Run the numbers across an average 50-account route. If you carry 30 cartridge, 12 DE, and 8 sand pools, your annual parts spend looks roughly like this: cartridge replacements at $300 average across 30 pools every 2 years equals about $4,500 per year, DE powder and grid replacements run about $80 per pool per year for $960, and sand media plus gaskets average $25 per pool per year for $200. Cartridge filters dominate your parts budget but DE filters dominate your labor budget.
This is why route valuation conversations always include filter mix. When buyers review pool routes for sale, the equipment inventory across accounts is one of the strongest predictors of true profit margin. A route that looks profitable on paper can collapse once you realize half the pools have aging DE grid filters needing $400 rebuilds in year one.
Recommending Upgrades To Your Accounts
Filter swaps are one of the cleanest upsells in pool service because the homeowner sees an immediate result: clearer water, less work for them, fewer calls to you. The best candidates for an upgrade conversation are sand filter owners frustrated with clarity, DE filter owners tired of the price of powder and grid rebuilds, and any pool where the existing filter is undersized for the gallonage.
Quote the upgrade as a turnkey service with the new filter, install labor, and disposal of the old unit included. Margins on filter installs typically run 30 to 45 percent when sourced through your distributor, and the recurring service revenue often increases slightly because you can justify a small monthly bump for the new equipment.
Picking The Right Default For Your Service Model
If you are building a route from scratch or absorbing new accounts, lean toward standardizing on cartridge filters wherever possible. They give you the best balance of clarity, weekly labor time, and predictable parts cost. Reserve DE recommendations for high-end pools where the homeowner values clarity above all and is willing to pay for the maintenance overhead. Keep sand on the table for budget accounts, rentals, and large commercial pools where flow rate matters more than micron rating.
The filter choice on each pool quietly shapes how many stops you can fit in a day, how often you carry parts, and how often a homeowner calls because the water looks off. Audit your current route, classify each pool, and use that data to price renewals and pitch upgrades.