In this article we look at how to maintain and troubleshoot your pool’s sand filter.

How does a sand filter work?

Although it might seem odd, sand is actually an extremely good filtering agent for pool water.

The sand that is used is ground down to a specific size – about 0.45 to 0.55 of an inch – and has a rough surface to help each grain trap debris.

The pool water enters the filter through a diffuser at the top of the unit and is then drawn down into and through a bed of sand.

A clean sand filter will trap a particle which is only 50 microns in size but, as the sand filter gets dirtier it actually gets more efficient trapping particles down to 20 microns.

Of course, as this happens the sand filter becomes clogged with dirt and then needs to be backwashed. You can tell that the filter needs backwashing when the pressure gauge shows about 10 lbs of backpressure, although it is good practice to backwash the filter weekly.

Changing the sand in a pool filter.

The sand in a sand pool filter won’t need changing very often; perhaps once in every five years or so.

If you do need to change the sand then you will need to buy special pool filter sand. It may be an idea to seek advice from your local pool professional as new and more efficient forms of filter media are available.

Turn the pump off and turn the Multiport selector to ‘Close’.

Open the lid on top of the filter. If the Multiport sits on top of your filter, this will mean disconnecting the pipes attached to it first.

Your filter instruction manual should show you how to do this for your particular make and model of pool sand filter.

You can then either scoop out the old sand from the filter or use a swimming pool filter sand vacuum that connects to the end of your garden hose and uses a Venturi effect to suck out all the sand.

Before you start to add new sand, you need to drain the filter by opening the drain plug and then check the filter laterals.

Laterals are finger like pieces of plastic that are pierced by small slots and distribute the water through the sand.

If any of the laterals are damaged or broken filter sand can get back into the pool. If you see sand on the pool floor below the outlet pipe, that’s a sign that the laterals may need replacing.

How to change sand filter laterals.

The laterals radiate out from the pipe that runs down through the middle of the filter and on first look, it seems as if they won’t be able to get out through the hole at the top of the filter.

In the majority of cases, each lateral is removable and replaceable individually, although there are models where this isn’t true and if one lateral is damaged the whole array must be replaced.

Once you are satisfied that all the laterals are in good shape you can begin to fill the tank with new sand.

If you have a Multiport valve that sits on top of the filter then make sure to tape over the top of the pipe the valve sits on so that sand doesn’t get in and clog the laterals.

Replacing the filter sand.

Fill the filter tank with water so that the laterals have at least 6 inches over them to protect them from the weight of sand being poured in.

Carefully and slowly pour in the filter sand making sure not to disturb the pipe.

Your filter instruction manual will tell you how much sand to add but the final level is likely to be about 6 inches from the top of the filter.

When you replace the Multiport valve it’s a good idea to replace the o-ring on the bottom of the valve and any other connections and lubricate it with a little silicon lubricant. Don’t forget to remove the tape that you applied to the top of the pipe before replacing the Multiport.

When everything is reconnected and the pump is primed and turned back on, backwash the filter for a couple of minutes to flush out any sand dust that may be there. Run the ‘Rinse’ cycle for 2 minutes and then switch the Multiport to ‘Filter’.

The pressure gauge setting that you get at this point is your clean sand filter pressure and so acts as the bench mark for when to backwash your filter again – when the pressure is 10 psi above that.

You backwash your filter in order to clean it. The more dirt and debris the filter collects, the more often you need to backwash, and backwashing increases the amount of water your pool uses and therefore the amount of chemicals that the pool uses.

Anything that you can do to decrease that water usage will make your pool cheaper and more environmentally friendly to run.

Making things more efficient.

A MultiCyclone is a pre-filter that water passes through before it gets pumped into your filter. The unit creates a vortex that spins out dirt and debris and retains it in a sediment chamber that can be easily emptied using very little water. Less dirt gets to your pool’s main filter so it needs to be backwashed less. As much as 80% less.

Triogen UV water treatment destroys organisms in your pool water by passing it through a chamber where it is dosed with UV light. The compact units have been designed for quick and easy fitting, so that installation is inexpensive.

The main benefit of switching to UV disinfection is improved water quality, as the Triogen TR2 unit controls algae, chlorine-resistant organisms and other unwanted life forms without having any harmful residual effect or leaving any by-product in the water.

Waterco Micron Bobbin Wound Filters are an innovative and efficient alternative to the traditional pool filter. The filter features a fishtail configuration that offers superior filtration by eliminating the dead areas commonly associated with a traditional star design.

This highly efficient design reduces the amount of water used during backwashing by up to 30%.

Waterco Micron Bobbin Wound Filters are manufactured from the highest grade of non-corrosive materials and are designed and built for many years of trouble free operation. The filter tank has a 10 year warranty on residential installations.

We hope that this article has been useful to you.

The maintenance of a sand filter can be tricky and if you need the help of a pool professional then we can help you find one in your area. If you click the ‘find a supplier’ link at the top of this article, that will get the process started.