how to improve your sand filter

[stevehaigh]

i know there are several old topics about this but most are so old they have been archived

my sand filter doesn't seem to be doing anything, i can run it all night and the water looks identical in the morning. at the moment i clean my pool once every couple of weeks with aluminum sulphate (san som) which is cheap but takes time and lots of water.

so, i don't want to replace my filter, mechanically i think its fine, but i wonder about the media. i've read a lot about zeolite but for everyone that loves it, there are plenty that hate it, especially here http://x.havuz.org/viewtopic.php?f=35&t=8415

i've also heard of people adding a few spoons of DE to a sand filter but in my experience, that can really clog up your filter fast.

i'm seriously thinking about replace the sand with better sand and using an inline cartridge filter after the sand filter. anyone try that?

i know the ultimate answer is probably to replace the sand filter with a DE filter but as always, i'm trying to do this on the cheap.

thx steve

[Chaichara]

Sand filters all work on the same priciple. Apart from imnor changes in design they have used the same principle for decades. Technological advances are usually limited to to the materials used in construction: fibreglass, polyester, thermoplastics, etc for the tanks, and various platsics, usually ABS for the laterals. i'm still running a filter in Europe that is so ancient it has stainless steel laterals. Some very cheap tanks have been known to split, and some brands - even well known ones - of multiport valves tend to wear out quicker than others, and the spider gaskets may not always be easy to obtain. Basically however, sand filters do the job they are designed for.

The choice of filter media is important and so is its maintenance. I've seen filters filled with all sorts of rubbish, but only genuine graded silica sand is guraanteed to provide a reasonably long working life and provide the correct level of filtration.

Zeolite, generally marketed here in Thailand as Zelbrite has excellent filtration properties and various studies claim it to be as good as D.E. In any case, it's my personal choice. D.E. is messy, needs constant attention, while Zelbrite will last for years and will certaily outlast sand by a long time before it comes to the unenviable task of changing your filter media. D.E/.filters are also expensive, and it's my guess that they are destined to goslowly out of fashion.

Crushed glass is also offered as a filter media for use in sand filters. It's more expensive than Zelbrite, but FWIW, I am not aware that it out-performs Zelbrite.

[Hugh Jarse]

Thanks for taking the trouble to post this. Most useful and helps when things go wrong and one needs to deal with local "experts". PM me if you can recommend a competent firm or individual to maintain a 16m X 6m salt pool.

Sand filters all work on the same priciple. Apart from imnor changes in design they have used the same principle for decades. Technological advances are usually limited to to the materials used in construction: fibreglass, polyester, thermoplastics, etc for the tanks, and various platsics, usually ABS for the laterals. i'm still running a filter in Europe that is so ancient it has stainless steel laterals. Some very cheap tanks have been known to split, and some brands - even well known ones - of multiport valves tend to wear out quicker than others, and the spider gaskets may not always be easy to obtain. Basically however, sand filters do the job they are designed for.

The choice of filter media is important and so is its maintenance. I've seen filters filled with all sorts of rubbish, but only genuine graded silica sand is guraanteed to provide a reasonably long working life and provide the correct level of filtration.

Zeolite, generally marketed here in Thailand as Zelbrite has excellent filtration properties and various studies claim it to be as good as D.E. In any case, it's my personal choice. D.E. is messy, needs constant attention, while Zelbrite will last for years and will certaily outlast sand by a long time before it comes to the unenviable task of changing your filter media. D.E/.filters are also expensive, and it's my guess that they are destined to goslowly out of fashion.

Crushed glass is also offered as a filter media for use in sand filters. It's more expensive than Zelbrite, but FWIW, I am not aware that it out-performs Zelbrite.

[tuffy]

Have you tried cellulose fiber? It works as a top coat on top of the sand bringing the filter medium up to DE standards. I have used it a few times. Most of it back washes out it seems to work pretty good.

[SwimmingPoolsThailand]

We fill the filters on our new pool builds with Zelbrite by default which we include in the price of the pool. We started recommending and using Zelbrite 12 years ago and have nothing but the best results and as far as we know, many clients are still using the first fill of Zelbrite filter media.

We occasionally follow links to forums about swimming pool problems but most often the complaints about filters and filter media are the experiences of one owner who is probably not a pool professional, or who has been given wrong advice by a 'professional'. Filter media cannot make your water go green. But an inadequate filter cycle or insufficient filter media in the filter tank, or insufficient backwashing won't improve the quality of the water. Some filter/pump installations may be undersized for the pool volume, and sometimes the pumping/filtration cycles may be set too short on the timer(s).

Most important is to maintain the pH at the correct level, then ensure that your sanitiser (chlorine or whatever else) is at the right level - the performance of the sanitiser depends heavily on the correct pH level.

Flocculant (aluminium sulfate) is fine as a fast remedy for particularly murky water, but it should not be used for regular preventative maintenance. For preventative maintenance consider dosing regularly with a dual-purpose liquid algaecide/clarifier.

Never, never, never use D.E. powder in combination with a sand (or Zelbrite) filled filter. Adding an additional in-line cartridge filter to the system is just doubling the equipment and doubling the maintenance work. Cartridge filters are reasonably efficient and a comfortable solution for owners of smaller pools, but the filter cartridges, which can be expensive, do need to be replaced sooner or later. The cartridges cannot be backwashed and must be removed for cleaning.

[PoolDoctor]

We had a challenging pool filter problem last month. We replaced the DE filter (headache to clean and manage) with a sand filter in a difficult underground equipment room. Trouble was, the original pump has simply too much for the new sand filter to handle. In a new pool water filling, it was simply blowing debris thru the sand media. No matter what we tried, we could not get the water clear. Operating pressure on the filter was 9psi, well within normal. As an afterthought, we re-installed the original DE filter just behind the sand filter with a by-pass valve for controlling the amount of water. Voila. Clear water in 6 hours. Now, they backflush the sand filter once a month, and clean the DE filter once a year. Once the pool settles down, we will slowly turn off the DE filter. If we can maintain clear water, we will remove the DE after that. TBD.

Gil

[kamalabob2]

I now use Zelbrite in the sand filter at my home. I had to replace the original unit that JD Pools installed at no small cost in 2008. I used a Buriram Water Pump shop to source the swimming pool pump, filters, salt and zelbrite. They had the staff who are familiar with out water cleaning tanks to come and install the not so expensive swimming pool pump and filters in a small town about 40 minutes from Buriram. I noted it was only a few baht more to buy swimming pool salt form this Buriram company than if I drove to the TRS factory in Korat. Pool and Spa seems to be the source of much of the equipment at this Buriram store, but the owner told me he sources swimming pool chemicals from several wholesalers in Thailand to be able to offer a lower price than most swimming pool companies. Mr. Pichai has the contract to supply swimming pool chemicals to several Buriram Hotels and a sports team pool which allows him to offer lower prices to private residential swimming pool owners in Buriram.

[KittenKong]

How much would this Zelbrite cost to replace the sand in a filter for a large condo swimming pool?

Is there anything that would make it unsuitable for such a pool?

We are being quoted 5000B for new "good" sand, but for all I know they are going to dig it up from Pattaya beach at low tide.

[sappersrest]

As an alternative crushed glass is an excellent filter media, I have used many hundreds of tons during filter refurbishments at local authority pools in the UK never had one complaint ,we are talking about 1.8m - 2.4 dia filters. with a bed depth of 1.2 m so would have no problem recommending crushed glass.

Just as a side note the best filter sand in the world comes from a place called Leighton Buzzard in the UK It is shipped all over the world including Saudi Arabia!!!

[edgarfriendly]

any ideas which sandfilter i might use on a 1000Gal pool?

so bored of scrubbing every 2-3 days...

would i still need to scrub/maintain anyway?

[sappersrest]

Flter size and type depends on the filtration rate required

and turnover time required.

The volume you gave equates to a pool 2.5m x 2m x1m deep are you sure your calcs are right?Most pool professionals work in litres or cubic metres not gallons now..

[SantiSuk]

Have had no issues with proper silica sand. I only need to backwash when the pressure gauge or fine sand round the return vents (towards the expiry of the sands lifetime) tells me to - every 2 or 3 months typically. I don't find replacing sand every 2-3 years a chore either if I choose a cool day/cool time of day. By all means go for the Zelbrite stuff, but let's not pretend that the older fashioned approaches are problematic or even inferior in quality - ie I cannot see how the performance of Zelbrite would improve my pool other than in the longer replacement cycles - for which you pay more money of course.

If someone wants to tell me what the Zelbrite equiv of 200kg of pool quality silica sand would cost and several people* can confirm what a realistic mean replacement cycle is* I could do the maths on whether it's worthwhile in the long run taking into account the time value of money as well. I'm guessing we would find that it is worthwhile if you pay someone for the labour to replace your sand/zelbrite but not if you are retired with time on your hands and the inclination to DIY!

* ie more than one guy, none of whom have a vending interest

[sappersrest]

Just found this very interesting article /advert on Certikins website. 

 

http://www.certikin.co.uk/oc-1-filtration-media.html

 

Will try and find out more Certikin do not mess about, or make false claims so will be very interesting

[SantiSuk]

I don't claim any expertise other than the fact I was a financial adviser to the UK government on water privatisation a couple of decades ago and therefore was shown round more than a fair lifetime's share of sewage treatment works.

 

Looks like the type of media they use for 'digesting' $hit - not to put too fine a point on it! The multitude of surfaces of plastic spheres like those pitured is there to leave multiple alighting points for bacteria to do get to work on impurities. Seems a bit odd it would be used when the main objective of pool filtering is to collect matter for later disposal to waste rather than purifying the water. Don't want to nay say it though - like i said I'm not really an expert.

[NickJ]

Backwashing often helped me. You can develop cavitation in the sand so the water pretty much just goes straight through. I got rid of the sand and used the stuff that comes from Australia.  

[sappersrest]

11 hours ago, NickJ said:

Backwashing often helped me. You can develop cavitation in the sand so the water pretty much just goes straight through. I got rid of the sand and used the stuff that comes from Australia.  

 

The reason for cavities /holes through the filter bed are usually due to one  of the following or a combination of

 

That pumps are two powerful for size of filter.

Infrequent backwashing i.e. fluidizing the bed.

Incorrect use of clarifiers i.e. alum especially used in conjunction with dry acid.(Causes a plaster of paris style substance to form at the bottom of the filter and around the laterals)

 

Any new technology or using technology from another industry is worth looking into, In general most swimming pools throughout the world  are still using roman methods of 2000 years ago i.e. sand filtration, think we should move on and try different technologies.

[sappersrest]

Sorry a bit of bum info typo error. Should read

Infrequent backwashing i.e.not  fluidizing the bed properly.

[madmax2]

I saw 2 men filling bags with beach sand at Phuket, i asked them what they were using it for and was told swimming pool filters

Using the correct grade of sand would probably fix the problem