Installing Your Pool, Stage 9: Setting Up The Filtration System

Where you are: pool full to mid skimmer, structure complete, safety labels on. If you are not there yet, go back to stage eight.

What you will have finished with: pump and filter set up, plumbed, and running.

This is the last assembly stage. After this, everything left is water chemistry.

It is also the stage where a small mistake costs you a wet equipment pad rather than a damaged pool, which is a relief after the last few. Take your time on the connections and you will be fine.

Before anything else: where the equipment goes

Your assembly instructions raise this in the safety section and it is worth deciding before you put a stone down.

Filtration components must not be positioned where someone could climb on them to gain access to the pool. The instructions ask for at least four feet of clearance for anything climbable, and that includes the filter, the pump and a heater if you have one.

This is not a technicality. A filter tank next to the pool wall is a step, and a child who cannot reach the ladder can absolutely reach the top of a filter.

So pick a spot that is:

At least four feet from the pool wall
Level, or able to be made level
Reasonably close to the skimmer and return, so hose runs are short
Near your electrical supply
Somewhere you can get to for backwashing and maintenance

Build the pad

This is where the patio stone from your stage one materials list gets used.

Level a 24 by 30 inch patio stone on a little stone dust or sand before installing the motor and filter.

Do not skip the levelling. A pump sitting on an uneven base vibrates, works loose over time, and stresses the connections. Bed it properly, check it with a level, and adjust the stone dust underneath until it sits flat and firm.

Then position the motor on the stone and insert the two nozzles that the hoses will connect to.

Then install the filter tank beside it.

Pump first, then filter. Doing it the other way round tends to leave you working around the tank.

Setting up the filter tank

The inside of a sand filter is simple but there is one step people get wrong, and the consequence is sand in the pool.

Fit the lateral assembly properly in its channel. The laterals are the finned arms at the bottom of the tank that let water out while keeping sand in. Sometimes they need installing individually, sometimes they come assembled.

Plug the center hole of the lateral assembly before you add sand. Your instructions are specific about this, and it is the critical step. That centre hole is the top of the standpipe, and if it is open while you pour sand in, sand goes straight down the pipe. You will then be picking it out, or living with sand blowing back into your pool every time you run the filter.

Cover it, then pour.

Add the sand. Use the quantity specified in your filter's own documentation, since it varies by tank size. This is the filter sand you bought in stage one, because the tank ships empty.

Pour steadily rather than dumping, and try not to knock the laterals out of position.

Remove the plug once the sand is in.

Install the joint in the cavity and secure the filter head.

Which way the filter head faces

One easy detail with a practical reason behind it.

Orient the filter head so the backwash position is on the opposite side of the pool.

When you backwash, dirty water comes out of that port. You want it pointing away from your pool and away from where people walk, not toward the wall you are trying to keep clean and dry.

Get this right now, because rotating a filter head later means draining and disconnecting.

The three hose runs

Your instructions give the order plainly. Install the necessary nozzles, then connect the hoses with their collars:

Hose one: from the top of the pump to the side of the filter head.

Hose two: from the motor to the skimmer, or to the bottom drain valve if you have one.

Hose three: from the front of the filter head to the water return. If you have a chlorinator, this run goes from the front of the chlorinator to the water return instead.

A backwash hose can be placed behind the filter head.

The logic, if it helps you remember: water leaves the pool at the skimmer, goes to the pump, gets pushed through the filter, and comes back to the pool at the return. Skimmer, pump, filter, return.

If you have a chlorinator or a heat pump, they are assembled at the filter outlet. Always after the filter, never before. Filtered water through your heater, and chemicals dosed after filtration rather than into your filter.

If you would rather run rigid PVC than flexible hose, our hard plumbing guide covers the benefits and the method.

The teflon tape technique

This is the most useful small thing in this entire stage and almost nobody does it properly.

Your instructions specify that all threaded nozzles must be wrapped with teflon tape before installing, to prevent leaks. But they also specify how:

Little or no tape on the first few threads, to make the fitting easier to start. Several layers toward the end threads, for better watertightness.

That is the part people miss. Wrapping evenly along the whole thread makes the fitting hard to start and can cross-thread it. Wrapping heavily only at the far end gives you an easy start and a tight seal where it matters.

Take the extra thirty seconds. Threaded connections at the skimmer and pump are where slow leaks start, and a slow leak at the pad means constantly topping up your pool and a permanently damp patch by your equipment.

If you have a drain valve, the same applies. Insert the threaded nozzles so the valve can screw into the skimmer, connect the drain hose to the bottom nozzle and the motor hose to the side nozzle, and tape every thread the same way.

Electrical

Your pump needs power, and this is licensed work.

Your pool should already be grounded from the wall stage, and the whole equipment area needs correct bonding and a GFCI protected supply. Requirements vary by jurisdiction and this is one of the things an inspector will look at.

Get a licensed electrician to do this part. It is not the place to save money, and our cost guide has this in the budget for a reason.

Starting it up

Not covered in your assembly instructions, so this is general practice.

Check every connection is tight before you switch anything on.

Prime the pump. Most above ground pumps need water in the housing to start. Fill the pump basket area with water, close it up, and make sure the water level in the pool is above the skimmer opening so water can feed in.

Set the filter head to the correct position for normal running, which on most multiport valves is Filter.

Never move the valve handle while the pump is running. That is the single fastest way to damage a multiport valve.

Switch on and watch. You are looking for water moving at the return jets, no air bubbling into the pool, no leaks anywhere on the pad, and no unusual noise.

Walk the whole system once it is running. Check every hose collar, every threaded fitting, the skimmer, the return and the pump lid. Any weep gets dealt with now.

Backwash once at the start, then set the valve back to Filter, to clear any fine dust from new filter sand.

What good looks like

Equipment at least four feet from the pool with nothing climbable
Pad level and firm
Laterals seated, sand in, standpipe plug removed
Filter head secured with backwash facing away from the pool
Three hoses connected in the right order with collars tight
Chlorinator or heater at the filter outlet
Every threaded fitting taped properly
Water moving at the returns with no air
No leaks anywhere

Before you move on

Equipment location chosen with the four foot climbing rule in mind
24 by 30 patio stone leveled on stone dust
Pump positioned first, then the filter tank
Lateral assembly seated in its channel
Center hole plugged before adding sand
Correct quantity of filter sand added
Plug removed, joint installed, filter head secured
Backwash port facing away from the pool
Hose one: pump to filter head
Hose two: motor to skimmer or drain valve
Hose three: filter head or chlorinator to return
Chlorinator or heater fitted at the filter outlet
Teflon tape light at the start of the thread, heavy at the end
Electrical done by a licensed electrician, bonded and GFCI protected
Pump primed, valve on Filter, system running with no leaks
Backwashed once, then back to Filter

The short version

Equipment goes at least four feet from the pool and must not be climbable.
Level the 24 by 30 patio stone on stone dust before anything sits on it.
Pump first, then the filter tank.
Plug the centre hole of the lateral assembly before pouring sand, then remove it. This is the step that keeps sand out of your pool.
Orient the filter head so backwash discharges away from the pool.
Hoses: pump to filter head, motor to skimmer, filter head or chlorinator to return.
Chlorinators and heaters always go at the filter outlet, never before it.
Teflon tape: little or none on the first few threads, several layers toward the end.
Electrical is a licensed job. Bonding and GFCI are code, not optional.
Prime before starting, never move the valve while running, and walk the system for leaks.

Next in this series: your first week of water care. The pool is built. Now it needs to become swimmable, and that takes a few days rather than a few minutes.