How to Use a Pool Sand Filter: Start-Up and Daily Routine

Using a pool sand filter comes down to one safe routine: with the pump off, set the valve handle to Filter, open the air relief on the tank, start the pump, and close the relief when water sprays out. On day one, write down the pressure gauge reading, because that clean number tells you when to backwash for the life of the filter. After that the handle stays on Filter, the pump runs on its timer, and your daily job is emptying baskets and glancing at the gauge.

Where Is the Pool Filter Located?

On an inground pool, the sand filter sits on the equipment pad: a concrete slab, often beside the house or behind a fence, that holds the pump, the filter, and any heater or chlorinator. On an above-ground pool, the filter and pump sit on the ground next to the pool wall, joined to it by two hoses. Either way, the filter is the largest round tank, plumbed directly after the pump.

Pentair’s Triton installation guide calls for a permanent concrete slab with room to stand clear of the tank, and Hayward’s S200 guide asks for the control valve and winter drain to be easy to reach. If you cannot find the equipment, follow the pipes away from the skimmer.

What order is the equipment in?

Water leaves through the skimmer and main drain, reaches the pump, then the filter, then any heater and chlorinator, and returns through the jets. Pentair’s guide says a chlorinator must never sit upstream of the filter, so the filter is always the first thing after the pump.

How do you recognize each part?

• The pump. A motor with a clear lid over a strainer pot that holds the pump basket.
• The filter tank. The big round tank full of sand, such as Hayward’s ProSeries or Pentair’s Triton.
• The control valve. Usually a multiport valve with a handle and labeled positions, on top of the tank or on its side. Hayward’s ProSeries sand filter ships with a 6 or 7 position VariFlo valve. Some Pentair filters use a two-position slide valve instead: handle down for Backwash, up for Filter. Hayward’s S200 guide labels the ports PUMP, RETURN, and WASTE.
• The pressure gauge. A small dial on the valve or the tank lid.
• The air relief valve. A small knob or cap on top of the tank that lets trapped air out. Hayward calls it the manual air relief, Pentair the manual air bleeder.
• The sight glass. A clear window on the waste side of the valve. Hayward says it shows when a backwash cycle is done.
• The waste line. The pipe or hose that carries backwash water away from the WASTE port.

Why the gauge climbs as the sand catches dirt is explained in our guide on how a pool sand filter works.

How Do You Turn On a Pool Sand Filter Safely?

Turn the pump off, set the multiport handle to Filter, open the suction and return valves, and make sure the pump basket is full of water. Open the air relief valve on the filter, then start the pump. Close the air relief once it sprays a steady stream of water, and check that water is coming out of the return jets.

The one rule that protects the valve: never turn the multiport handle while the pump is running. Hayward’s S200 guide puts it plainly: “always shut off pump before switching Filter Control Valve positions.” Pentair and Intex give the same instruction. Hayward and Intex also tell you to push the handle down before turning it, which Hayward says prevents damage to the valve seal.

Starting a new filter or fresh sand

A new filter starts on Backwash, not Filter, to flush dust out of the sand. Hayward’s S200 guide says to run at least 2 minutes once flow out of the waste line is steady, then stop the pump, set Rinse, and run until the sight glass is clear, about 1/2 to 1 minute. Pentair says to backwash until the waste water is as clear as the pool water. Then stop the pump, set Filter, and restart.

The exception is a new concrete or gunite pool, or any pool with heavy plaster dust: Hayward says to start on Filter, because Backwash would push that debris into the underdrain laterals and clog them. Pentair adds a backwash after about 48 hours of running on a new pool.

Restarting after the pump has been off

1. Turn the pump off at the timer, breaker, or switch.
2. Check the handle is seated on Filter, not between positions.
3. Open the suction and return valves. Hayward warns that starting with them closed can cause serious injury or property damage.
4. If the pump pot has drained, fill it first; our walkthrough on how to prime a pool pump covers a pump that will not catch.
5. Open the air relief, stand clear of the tank, and start the pump. Pentair explains that trapped air gets pressurized and can force the top closure off.
6. Close the relief when it sprays water, then check the returns and read the gauge.

Why Should You Write Down the Clean Pressure on Day One?

The clean pressure is your filter’s baseline, and every backwash decision is measured against it. There is no universal normal number: Hayward’s S200 guide says the clean reading varies from pool to pool with the pump and piping, and Pentair’s start-up steps end by telling you to note the operating pressure while the filter is clean.

Take the reading after the first start-up, with the pump on Filter and the baskets empty, and write it with the date on a tag on the tank. If your pump has more than one speed, the gauge reads differently at each, so record it at the speed you run most.

Repeat the reading after every backwash. Pentair says that if the post-backwash pressure sits 4 to 6 PSI above your original clean number, the sand needs a chemical cleaning. Typical ranges and what high or low readings mean are covered in our guide to what PSI a pool filter should be at.

A gauge that never moves or is fogged inside cannot give you a baseline. Hayward’s European guide has the gauge screwed in by hand, so swapping a dead one is a small job.

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Which Valve Setting Do You Use for Each Job?

Filter handles almost everything, including routine vacuuming and clarifier. Backwash and Rinse clean the sand, Waste handles heavy vacuuming and lowering the water, and Recirculate mixes chemicals without filtering. The pump is always off while the handle moves.

Clarifier goes on Filter because it clumps fine particles into pieces large enough for the sand to catch; on Recirculate those clumps would skip the sand. If you are dosing a pool clarifier, run the pump on Filter for the time on its label. Hayward’s European guide describes Recirculate as the setting for fast dispersion of chemicals or a heavy chlorine dose; nothing is filtered while it is selected.

Every position, including the Winter notch and what each one does inside the valve, is laid out in our pool filter valve settings guide.

What Is the Daily Routine for a Sand Filter?

Let the pump run its scheduled hours on Filter, empty the skimmer baskets, compare the gauge with your clean number, and look at the return jets for strong flow without bubbles.

The manuals disagree on run time, so set the timer by turnover rather than a fixed number. Hayward’s S200 guide asks for at least one full turnover of the pool water a day. Hayward’s European guide suggests 6 to 8 hours on Filter, Pentair’s Triton guide sets a design minimum of two to four turnovers in 24 hours, and Intex’s operating table works out to roughly 1 hour per 1,000 gallons.

Full baskets are the usual reason a sand filter underperforms: Pentair’s troubleshooting chart blames weak returns with a low gauge reading on a clogged basket or suction line. Hayward’s problem list adds that bubbles coming back into the pool point to an air leak on the intake side. A gauge that creeps up over days is normal; one that jumps overnight often means a partially closed valve, which Pentair lists as a cause of high pressure.

What Should You Check Every Week?

Record the gauge reading, empty the pump basket with the pump off, test the water, and look the filter over for drips or cracks. Backwash only if the gauge says so.

• Log the gauge. Intex’s manual says to check it weekly; a written log shows the climb toward your backwash point.
• Empty the pump basket. Pump off, basket emptied, lid O-ring wiped, pot refilled before restarting.
• Test the chemistry. Hayward and Pentair both list free chlorine at 1 to 3 ppm and pH at 7.2 to 7.6. As Pentair’s guide points out, a filter removes particles but does not sanitize the water.
• Inspect the equipment. Pentair says to replace any cracked or deformed part found during routine servicing, because a damaged closure or fitting can let the top separate under pressure.

When Does the Gauge Tell You to Backwash?

Backwash when the gauge climbs 6 to 10 PSI above your clean number, depending on your manual. Hayward’s S200 guide says 6 to 8 PSI, while its current ProSeries manual says 8 to 10 PSI. Pentair’s Triton guide and Hayward’s European sand filter guide both say 10 PSI. Intex’s gauge has colored zones, and its manual says to backwash once the needle reaches yellow. The widely quoted 8 to 10 PSI rule sits inside that range.

Pentair calls the gauge the most common method but not the most accurate. With a flow meter, it says to backwash when flow drops about 30 percent from clean, for example from 60 GPM to 40 GPM. Without one, noticeably weaker return jets are the same signal.

Do not backwash on a calendar. Pentair warns against a timed schedule such as every three days and says backwashing too often actually causes poor filtration. Its fix is to let the pressure build to 10 PSI over clean first.

In brief: Backwash until the sight glass runs clear, Rinse briefly, then back to Filter, with the pump off for every handle move. Pentair gives roughly 3 to 5 minutes of backwash and 30 seconds of rinse; Hayward’s S200 guide says about 2 minutes or less of backwash and 1/2 to 1 minute of rinse. The full procedure is in our guide on how to backwash a sand filter.

How Do You Use an Intex or Above-Ground Sand Filter Pump?

The routine is the same with smaller parts: pump off, handle to Filter, plunger valves at the pool wall open, air bled from the pump housing, timer set. Intex’s Krystal Clear SX pumps differ from inground systems in three ways: a much lower pressure limit, a gauge with colored zones, and a built-in timer.

Where it sits and how it connects

Intex’s SX1500 manual asks for a solid, level, vibration-free base, placed away from the pool so children cannot climb on the pump to reach the water. Plug it into a GFCI-protected outlet; Intex specifies a GFCI or RCD rated at 30 mA maximum.

The two hoses run to plunger valves on the pool wall. Turn both handles fully counter-clockwise to open them before starting, and close them before opening the strainer or disconnecting a hose, since the pump sits below the waterline.

The 6-way valve, air release, and timer

Intex’s manual lists Filter, Backwash, Rinse, Waste, Recirculate, and Closed; on the Intex SX2100 the Waste position is labeled Drain. Switch the pump off and push the handle down before every turn. To bleed air, unscrew the air release valve on the pump housing until water flows out, then close it.

On the SX1500, press ON/OFF until 00 flashes, set 01 to 12 hours with the TIMER button, and lock the keypad; the pump then runs at the same time every day, and FP mode runs it continuously. Intex’s table allows 1 hour per 1,000 gallons on non-Intex pools, and lists 4 hours for a 15 ft x 42 in Easy Set (3,284 gallons) and 7 hours for an 18 ft x 48 in Metal Frame (6,423 gallons).

Reading the gauge

Record the reading with clean sand, check it weekly, and backwash when the needle reaches yellow. Intex adds a useful check: after vacuuming, remove the vacuum and see whether the needle drops back to green before you backwash. The maximum working pressure is 20 psi (1.4 bar), far below the 50 psi Hayward and Pentair list for their inground tanks. Intex backwashes until the waste outlet runs clear, then rinses for about one minute.

Assembly, hose routing, and the first fill are covered in our guide on how to set up an Intex pool pump and filter.

Which Mistakes Damage a Sand Filter?

The costly ones are turning the handle under pressure, running against a closed valve, skipping the air relief, running the pump dry, skipping Rinse, and using the wrong sand. Each has a documented consequence in the manuals.

• Turning the handle while the pump runs. Hayward says this strains the piping and valve. The handle moves a diverter that presses on a rubber seal, and dragging it across the ports under pressure wears the seal until water slips between ports, often as a trickle from the waste line on Filter.
• Running on Closed or against a closed valve. Hayward’s European guide says never to use Closed with the pump running. Pentair warns that running with no flow seriously damages the equipment, and that a closed outlet valve disables the tank’s internal air relief and risks the tank separating.
• Skipping the air relief or touching the lid under pressure. Pentair says pressurized air can force the top closure off the tank and cause severe injury, and that the closure must never be tightened or loosened with the pump running.
• Running the pump dry. Pentair’s start-up steps begin by checking that the pump pot is full of water. The shaft seal relies on that water for cooling, and a dry run can ruin it.
• Skipping Rinse. Hayward’s S200 guide says Rinse sends the dirty backwash water to waste instead of back to the pool. Skip it and that dirty water goes straight back out through the returns.
• Using the wrong sand. Pentair lists improper sand size as a cause of sand loss to waste, and both Hayward and Pentair specify No. 20 silica. When the bed needs replacing, buy bagged #20 silica pool filter sand, not play sand.

How Do You Start a Sand Filter After Winter?

Start it in the reverse order of closing: refit the drain cap and pressure gauge, pull the winter plugs, refill the pool to the middle of the skimmer opening, set the valve to Filter, then prime and start the pump with the air relief open. Get the filter running cleanly before you balance or shock the water, because shock mixes poorly in still water and the filter cannot catch what the shock kills until the system is moving.

1. Refit the drain cap and gauge. Hayward’s S200 guide leaves the drain cap off for the whole winter, so it goes back on now. Check its O-ring, and wrap the gauge threads with PTFE tape before screwing it in.
2. Pull every winter plug from the returns and skimmer lines and reconnect any unions you opened. A plugged line is a closed valve, and Hayward warns that starting against closed valves can cause serious injury or property damage.
3. Refill to mid-skimmer so the skimmer cannot gulp air.
4. Seat the handle on Filter with the pump off.
5. Prime and start using the restart steps above, closing the air relief once it sprays water.
6. Read the gauge once it settles and compare it with last season’s clean number. If the sand ran poorly at the end of last season or looks gray and clumped, check our guide on how often to change pool filter sand before you start chemical treatment.

For above-ground pools that were taken down or had the pump stored indoors, reassemble the hoses and plunger valves first; the Intex pump and filter setup guide walks through the connections.

How Do You Shut a Sand Filter Down?

For a normal day, turn the pump off at the timer or switch and leave the handle on Filter. For service work, Pentair says to turn off the pump and any automatic controls, open the air bleeder, and wait until all pressure is relieved before touching the lid or valve. For winter, the tank is backwashed, drained, and left open.

If your equipment sits below the pool’s water level, Pentair’s guide says to close the appropriate valves before opening anything, or the pool will drain through the open pump or filter.

Pentair’s winter order is backwash, pump off, air bleeder open, multiport on Winterize so the diverter puts no pressure on the rubber seal, and the drain plug out for the whole season. Hayward’s S200 guide also leaves the drain cap off, with the handle between two positions so the valve can drain.

Related Guides

• How Long Should a Pool Filter Run?: set the timer by pool size and pump flow
• How to Vacuum a Pool With a Sand Filter: when to vacuum on Filter and when to switch to Waste
• How to Backwash an Intex Sand Filter: the Intex 6-way valve sequence step by step
• How Often to Change Pool Filter Sand: the signs a sand bed is worn out
• How to Winterize a Pool Filter: the full shutdown for freezing climates
• Pool Filter Multiport Valve Problems: leaks, stuck handles, and a worn valve seal