Sand filters | Filters

Sandfilter Troubleshooter

- when Sand-filters go wrong . . you need to find out what's wrong quickly and rectify it even more quickly because without a filter you've got a problem that can, andalmost certainly will, rapidly escalate to even more expensive problems

Warning: - Due to the possibility of residual pressure in the filter itself, or back-pressure from the pool, take these simple steps before opening the filter

Switch the pump off

Open the air-relief valve (or loosen the pump lid)

Close all the valves

Cloudy water possible causes -

The filter is full -
Cure: - Backwash and rinse the filter

The media is old, tired and needs replacement -
Cure: - replace the media but think about using Zeolite instead of sand

Some of the media has escaped from the filter leaving insufficient to catch all the suspended dirt, some of which returns to the pool via the Jets. Particularly noticeable when vacuuming the pool
Cure: - Well, it’s not simply a matter of topping up the media because there is always an underlying reason WHY the media has escaped

It could be any of the following: -

The pump is too powerful for the filter and, during a backwash, some of the media is pumped out with the waste water

Pool builders sometimes offer a bigger pump as a 'free upgrade' when trying to outsell their competitors and, consequently, many pools have pumps that are far too big for the filter

Check online with the manufacturers for the recommended pump size for your filter model

The media has eroded due to turbulence when back-washing

The tiny fragments of media are likely to be caught by the remaining media and then flushed out of the filter during the next backwash, with a gradual reduction of the total media within the filter

Sand is coming into the pool at the return jets

One or more of the collectors in the lateral assembly is worn, cracked or broken - allowing sand to be pushed through and into the pool or
The breather (pressure relief) tube in the filter has broken

Cure: - empty the filter and examine the collectors and breather tube; replace as require
You may as well replace the media whilst you're at it!

Filter need frequent back-washes possible causes -

Insufficient time allowed for each backwash
Cure: - Backwash until the water in the sight-glass runs clear

Insufficient flow through the filter
Cure: - First check that the pump strainer basket and impellers are not clogged as either of these will severely reduce flow - and backwashing will ineffective

Tip:- Run the system on Filtration and observe how much water is returned to the pool at the Jets. You can do this just by feeling the force of the water with your hand. Then stop the pump and turn the Rotary Valve to 'Circulate'. Now run the pump again and decide if the force of the flow has increased

If there is an increase - the filter is the culprit
If there is no increase - the pump is the culprit

Incorrect water balance
Cure: - maintain a pH of 7.4, or as close as possible, and maintain free Chlorine at 1-3ppm
This will stop algae from growing in the filter and also prevent calcification of the filter bed
Check and adjust Total Alkalinity and Calcium Hardness levels

The filter is calcified

Cure: - Remove the sand and replace it with new media

Calcification is caused by high pH of the water so check and adjust pH as required; aim for a pH of 7.4

Leaking filter

The course of action to take depends on where the leak is coming from: -

From the seal between lid and filter

Cure: - Remove the lid and examine the rubber sealing ring ('O'-ring gasket)

If you spot any damage at all, and this includes any breakdown of the rubber (it will leave black stains on your hands), replace the sealing ring

Clean the seating and sealing ring thoroughly, smear them both lightly with silicone grease or Vaseline, replace the lid

Note: - Some older types of filter lid can become distorted over time, particularly if the pump is over-sized

In this case, replace the lid with a new one and check that the pump is the correct size for the filter

From one of the compression fittings to the Rotary Valve

Cure: - Tighten the clamp-ring of the offending item, but be careful not to over-tighten because they can split

Filter connectors are sealed by squeezing a rubber 'O'-ring between 2 flat flanges

Eventually, the 'O'-ring can flatten, reducing its ability to seal the joint

Replace defective or damaged 'O'-rings as required

Tip: -

Usually 'O'-rings are retained in a groove on one of the flanges and the flattening occurs on the side of the ring that is pressed up against the other flange

In a emergency you could try removing the 'O'-ring and putting it back other-side-up

You'll still need to replace it at a later stage though

From a crack or split in the filter body

Cure: - Do not attempt to repair a cracked filter - replace it with a new one

Pool filters are 'pressure vessels'; meaning that they are under pressure during the filter sequence

We have seen filters that have literally been blown apart by pressure from the pump

If your repair fails you could have a catastrophe on your hands. This could include: -

A flooded pump-room - causing further damage to the pump and/or other electrical items

An empty pool - if the water is not being returned to the pool because it is escaping from a split filter

If the water table is high your pool could float up out of the ground and you'll never get it back down again

Subsidence - if the water is flowing near the pool, or even worse near the foundations of the house, subsoil can be washed away, causing subsidence

From the pressure gauge or drain plug screw-thread

Cure: - Remove the offending item and wrap 20 turns of PTFE tape around the male thread before re-fitting

We supply all plant and equipment featured on this website. All our work is Guaranteed; Parts and Labour

For free and unbiased advice, a site visit or no-obligation Quotation*, please make initial enquiries by email. Tell us a little about your pool problem and include a daytime phone number. Thanks, we look forward to meeting you soon

Note: - Please contact our recommended pool professionals for supply and installation of all pool-related services: -

Andalusia and the Costa del Sol - Pool Safety Spain

Nerja area - This email address is being protected from spambots. You need JavaScript enabled to view it.

*We only offer Quotations: - a fixed, agreed price that cannot, and will not, be increased. We do not give 'estimates', as an estimate offers the client no guarantee of final price

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Ken Walker - MyPoolGuru©

Replacing Sandfilter Media

- every 4 years or so it's time to replace the sand in the filter, and this is how you do it: -

Switch the pump to ‘Off’ and close all Valves

Set the Multi-port (Rotary) Valve to the ‘Closed’ position

Remove the lid of the filter and, immediately underneath, you will seea plastic fitting that looks like a large-hole watering-can sprinkler rose

This is the ‘diffuser’ and must be removed from the filter by gently twisting and pulling, to allow access to the inside of the filter

Notes: -Some filters incorporate a screw-thread fitting to attach the diffuser. Some filters have a specially shaped underside to the filter lid which acts as a diffuser, so don’t worry if you don’t have a separate diffuser

Normally there is air relief tube extending up through one of the holes in the diffuser - this tube allows pressure to be balanced between the top and bottom halves of the filter - take care not to damage the tube or breather-cap which is fitted to the top of the tube

Now you can get at the filter media for removal

Wear rubber gloves and use an empty can or plastic jug to scoop out the sand

Put the removed sand into a bucket for later dumping

Take care not to damage the plumbing inside - feel your way until you are familiar with the layout of components

Once most of the media has been removed unscrew the collectors from the central hub of the lateral assembly for inspection and possible later renewal

Use a little residual media and water to scour the inside of the filter vessel and then remove the remainder of the media

Wash the top and outside of the filter and the screw threads of the collector hub with a hose to remove any grains of media

Check, and if necessary change, the 8 or more ‘collectors’ or ‘laterals’ in the lateral assembly, which are fitted like spokes on a central hub at the bottom of the filter; buy them at your local pool-shop but take an old one along with you for comparison because there are several sizes

A typical collector from the lateral assembly

Replenishing the filter media: -

Consider changing the media to Zeoclere-30 - it's a little more expensive than Silex but filters much better and last for 10+ years - far longer than Silex, and also strips ammonia and dissolved metals from the pool.

There may be an information label, on the outer surface of the filter, which details the filter Make/Model and the quantity of Silex within it

Very often this is missing or illegible and you will have to guess how much you need, using the amount removed as a rough guide

Note: Zeoclere-30 is approximately 80% the density of sand so you need only 80%-by-weight: - thus if your filter contains 100Kg of Silex you need only 80Kg of Zeoclere to re-fill the filter

Place a can or plastic jug over the upward-facing opening to the inlet pipe to avoid filling it with the new media

Pour new media into the filter and add water to help it to settle

The correct level is to the top of the horizontal section of the upper pipe. (It’s simple once you see the inside of a sand-filter)

If you add too much media the level will adjust automatically during routine back-washing, when the excess will be gradually flushed out

Rinse any grains of filter media from the filter lid, nuts and caps, or lid screw thread as applicable

Examine the filter lid ‘O’ ring and replace if it is damaged in any way

Smear the ‘O’ ring with a thin coating of silicon grease or Vaseline and thoroughly clean the underside of the filter lid and the filter seating

Fill the filter with water, replace the lid and tighten down carefully

Set the Rotary Valve to ‘Backwash’ and open the Bottom Drain and Waste valves

Backwash the media for several minutes to remove dust, and then Rinse as normal

If you are re-filling with Zeolite you should backwash each bag thoroughly before putting the next bag in - it’s more time-consuming but the results are worth it

Check for leaks during the 'Rinse' process and rectify them

Repeat the cycle until the water runs clear

Set all the Pump-room Valves and switches to ‘Filtration’

Congratulations! - you have just renewed the filter media and collectors!

Now go and rest your back for three days

The old media should not be used for building purposes, in a garden or in a sand-pit

We supply all plant and equipment featured on this website. All our work is Guaranteed; Parts and Labour

Note: - Please contact our recommended pool professionals for supply and installation of all pool-related services: -

Andalusia and the Costa del Sol - Pool Safety Spain

Nerja area - This email address is being protected from spambots. You need JavaScript enabled to view it.

*We only offer Quotations: - a fixed, agreed price that cannot, and will not, be increased. We do not give 'estimates', as an estimate offers the client no guarantee of final price

Zeolite

- an exceptionally good Pool Filter Media

What is Zeolite?

This naturally occurring mineral was formed aeons ago when volcanic ash fell into saltwater lagoons.

Our zeolite is marketed as ZEOCLERE-30

Zeoclere has many advantages

over normal sand-filter sand (Silex) due to its porous, 'honeycomb' structure

With its open structure Zeoclere-30 has a surface area over 400 times greater than filter sand

Additionally, Zeoclere-30 helps strip ammonia from the water by absorption, and removes metals by ionic attraction

Filtration to better than Diatomaceous Earth (DE) standards, with the convenience of Silex

Reduces pool chemical usage and enhances Chlorine performance

Reduces pool odour, eye and skin irritation

Zeoclere-30 offers significant savings in the cost of maintaining pool water in optimal condition

Keeps your pool sparkling clean - cleaner than a DE filter (2-3 micron filtration)

Zeoclere-30 lasts much longer than ordinary filter sand - at least 10 years and often even longer

Simple to install, and it works in all sand-filters

Filters need 80% of the weight of Zeoclere-30 (compared to Silex) i.e.- if your filter takes 100 Kg of Silex sand you'll need only 80 Kg of Zeoclere

Zeoclere-30 is the most advanced filter media to be introduced to the Swimming Pool industry in many years

When compared to traditional filter sand Zeoclere-30 has many advantages

We supply all plant and equipment featured on this website. All our work is Guaranteed; Parts and Labour

Note: - Please contact our recommended pool professionals for supply and installation of all pool-related services: -

Andalusia and the Costa del Sol - Pool Safety Spain

Nerja area - This email address is being protected from spambots. You need JavaScript enabled to view it.

*We only offer Quotations: - a fixed, agreed price that cannot, and will not, be increased. We do not give 'estimates', as an estimate offers the client no guarantee of final price

Silex

The commonest filter media used in sand-filters is Silex - it's cheap, available and familiar

(It's also not the best thing to put in a sand-filter; more on that subject here)

The vast majority of sand in the world, when examined under magnification, can be seen to be rounded

This is because it has been formed by rocks banging into each other in water in rivers, on beaches, etc., which tends to knock the sharp edges off

It's pretty - but it's absolutely no use at all in a sand-filter

The rounded grains do not pack together very tightly (imagine a box full of basketballs - and how much empty space there is in between them)

Silex

Pool-filter sand, on the other hand, is produced by crushing and sieving silica rock, leaving the sharp Angular Sand Grains edges intact

These sharp edges help the sand to 'pack down' tightly, leaving tiny gaps and passages between the grains

It is the size of these gaps that determines how small a particle the filter can trap

When newly installed to a filter Silex will remove particles down to around 15 microns but, over time, the passage of water (bearing particles smaller than 15 microns) will erode the sharp edges and therefore the spaces between the grains will become larger

The particles that are knocked off the individual grains during this erosive process get flushed into the pool and are unlikely to be trapped by the filter during vacuuming, so they will be returned to the pool and make the water cloudy

After 4 years or so the sand will be unable to trap particles smaller than 25 microns and the water will never appear completely clear again until you change the media

A micron is one-millionth of a meter and it is impossible for humans to see anything smaller than about 35-40 microns but, in huge numbers they can impart a cloudiness to the pool

We supply all plant and equipment featured on this website. All our work is Guaranteed; Parts and Labour

Note: - Please contact our recommended pool professionals for supply and installation of all pool-related services: -

Andalusia and the Costa del Sol - Pool Safety Spain

Nerja area - This email address is being protected from spambots. You need JavaScript enabled to view it.

*We only offer Quotations: - a fixed, agreed price that cannot, and will not, be increased. We do not give 'estimates', as an estimate offers the client no guarantee of final price