Changing filter media in pool filter - how often

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Changing filter media in pool filter - how often

Postby pattayapope » Mon May 23, 2011 11:48 am

On my pool filter it has a lable attached which says the filter media should be changed out once a year, any advice or recomendations as to frequancy of change out would be appriciated.
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Re: Changing filter media in pool filter - how often

Postby otis-a » Mon May 23, 2011 1:14 pm

Typical cartridge filters are changed based on pressure drop (pump performance and pump electrical cost vs filters cost being the true criteria)
the typical allowed dP at change out ranges between 10 and 20 psi or 1 atmosphere pressure drop
for sand filter types- the backwash cycle is empirically determined. it is based on volume passed, particle load of filtered volumes and sand bed volume. Also dP can be used but is typically measured in inches water or cm water for u metricators
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Re: Changing filter media in pool filter - how often

Postby jazzman » Sun Jun 12, 2011 2:58 pm

A little less technical:
Let's look at the kind of filters that are used because you don't say what kind you have:

Cartridge filters
A bit like printer ink cartridges, it's a captive market - you'll forever be paying for cartriges.

Diatomacious earth
Still sold, but no obvious advantages over any other systems except it's better than standard silica sand. The DE needs changing,sooner or later, but in spite of 30 years on and off in the pool business, it's a system I avoid so don't know much about it.

Sand
The most widely used system and media. Fine silica sand should be used, but some filters have been found to have been filled with anything including general purpose building sand and even grit. Sand needs changing, sometimes as often as every 4 or 5 years or even sooner if the pool has a permanent algae problem. Changing the sand is problematic because the very heavy filter unit full of damp media can weigh as much as 100 Kg and has to be removed completely and carefully to avoid damaging the unit and surrounding plumbing. Not something you really want to do too often.

Sand filters can also be filled with alternative media - best done with a new pool. Zelbrite® and DiamondKleen® are the commonest and while only around two thirds by weight is required in contrast to sand, they have infinitely better filtration properties, will last for a very long time and are worth the investment. DiamondKleen is crushed silicone dioxide and costs about 1,000 - 1,200 baht per 15 Kg bag depending on the retailer. Zelbrite is a volcanic product and costs around 600 - 900 baht per 15 Kg bag. A typical domestic pool filer for a 32 - 40 sq. m. pool will need 4 - 6 bags. Can last as long as 10 years or more. Saves money on filtering time and backwashing. Excellent results when used with salt water chlorinators. See other threads in this swimming pool forum for more details of these products.
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Re: Changing filter media in pool filter - how often

Postby pattayapope » Mon Jun 13, 2011 9:42 am

Jazzman

I waited a while for you reply, guess you have been offline for a while, anyway it is one of those big fiber glass tanks with screw on top and multiport valve on the side. Just wanted to know if I follow the pool suppliers recomendation or what signs would I get that filter media needs changing?
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Re: Changing filter media in pool filter - how often

Postby jazzman » Mon Jun 13, 2011 4:09 pm

Hi. yes, I've been away on a big pool project in a remote area with almost no Internet possibilities. It sounds as if you have a standard traditional sand filter, but it would be unusual for the manufacturer or supplier to recommend changing the media once a year - it really is a tricky job. There are generally no signs that the media would need changing unless over the years you have noticed a perceptible drop in filtration performance. Just to be sure, could you post a photo of it or let me know the brand and type?
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Re: Changing filter media in pool filter - how often

Postby jazzman » Tue Jun 14, 2011 10:16 am

I've searched the board and found this earlier thread of mine:
http://www.coolthaihouse.com/forum/viewtopic.php?f=19&t=782&p=11370#p11370
It might help. I still swear by DiamondKleen® but for for practical reasons of product supply and price I have switched to Zelbrite®. A very large and complex pool (720 m2) I was a design consultant for 10 years ago uses Zelbrite (DiamondKleen hit the market later) which still has not needed changing. There is a supplier of DiamondKleen in Pattaya, and the Zelbrite importer is in Lad Krabang near the Bang Na highway.. E-mail Dozer for details.
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Re: Changing filter media in pool filter - how often

Postby pattayapope » Thu Jun 16, 2011 8:12 am

Jazzman

As requested a photo of my filter system for the pool

DSC05688.JPG
Picture of media filter not sure what is inside probably regular sand


DSC05689.JPG
Lable indicating media needs changing
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Re: Changing filter media in pool filter - how often

Postby jazzman » Sun Jun 19, 2011 11:13 pm

Yes, a standard sand filter. This will be a complex affair to change the media, because the filter unit, even after it is drained, will weigh about 100 Kg or more with the damp media, and the surrounding pipework will have to be removed to get it out. It needs to be turned upside down to remove the old media. No media in this kind of filter that I know of needs changing yearly. Labour time for the intervention: about four hours. Refilling with new media at around the prices I mentioned previously. Get quotes from plenty of pool service firms before doing anything, and let us know here what they quoted. I see you have a good quality Hayward® pump and the installation looks quite new, if very cramped. (a lot of 90 degree elbows rather than wide radius corners in the pipework too, but professional ball valves and screwed barrel unions that may make the work easier).
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Re: Changing filter media in pool filter - how often

Postby domino » Tue Jun 21, 2011 4:49 pm

well it surprises me that a so called expert as jazzman doesn't know anything about a DE filter ,( sorry) it is common knowledge ( you can google ) that a DE filter filters a lot better than a sand filter,you can not even compare ... as i have one all ready 8 years , and i never had any problem with the pool and always very clear water , i wouldn't advice anybody to buy a sand filter ( even with zeolite) as of the inadequate filtering , as of maintenance of a DE filter , very easy , i take out out the element , clean it with the water hose, put back , coat with DE powder all takes about 30min....( you even have DE filters you can backwash same system as a sand filter , but i prefer the system i have ..)i have a friend with same size pool as me , with sand filter( zeolite) and he is always surprised when he visit us how clear the pool water is, as he has always many problems, and finally is going to follow my advice and replace his sand filter with a DE filter as i am sure all his problems will be over.... :wink:
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Re: Changing filter media in pool filter - how often

Postby domino » Wed Jun 22, 2011 12:34 pm

first i did not mean to insult anyone , i was only surprised of the one sided story...
and indeed leave the readers choose for them selves...
as info read also this: Q: What is the difference between a Sand, Cartridge, or D.E. filter

A: Sand – Filter Range 20 to 40 microns. The oldest and most popular method of filtrations is sand. Sand filters use a special filter sand, normally .45 to .55 mm (also known as pool-grade #20 silica sand), because it has sharp edges that serve to separate particles, allowing filtration to take place. Sand filters are the least expensive of the three types of filters but only filters particles down to 20 to 40 microns in size.

Cartridge – Filter Range 10 to 20 microns. Cartridge filtration has been available for a relatively long time, and recently has begun to enjoy rapid growth and acceptance. When water passes through a cartridge filter, dirt is screened out at the surface of the cartridge element. When clean, the element will trap larger particles, with finer particles being filtered out as the pores of the element become clogged by the larger debris. The cartridge element can be removed and cleaned by pressure washing inside and out with a garden hose.

D.E. (Diatomaceous Earth) – Filtration Range 1 to 3 microns. Many pool professionals consider D.E. filtration to be the finest, because it is capable of removing smaller particles than either sand or cartridge. Diatomaceous earth is a porous powder with microscopic openings, that, when magnified, look like tiny sponges. Clear water can pass through these openings but particles, as small as one to three microns are trapped the first pass
through the media. All D.E. filters have internal elements that become coated with D.E. It is this “filter cake” that strains dirt, dust, algae and some forms of bacteria from the water. Similar to sand filters, when a D.E. filter becomes dirty, it is cleaned either by back washing the clogged D.E. to the “waste” line or regenerating and draining. To restore filtration, a fresh “charge” of D.E. is added to the filter.
you can find several websites telling the same story......
and as of expensive , my pump and filter from sta-rite ( american made) has cost me 36.000 baht ( set) , price now 40.000 baht...,
1 HP pump adequate enough for my pool from 10 x 5 M...i clean the filter about every 2-3 months depending the usage of the pool, using each time ,2.7kg of DE powder, 1 bag 20kg = between 900-1200 baht ....
as my friend bought his stainless sand filter alone at 40.000 baht? ( and it is thai stainless, he also all ready had to fix it...)
no matter what system you choose , as long as you are happy...so for me DE filter , and never sand filter.... :wink:
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Re: Changing filter media in pool filter - how often

Postby jazzman » Tue Sep 24, 2013 8:17 am

An old thread, but 'ike so many, it could do with some updating.

I was being a bit superficial when i said I didn't know much about D.E. filters. in fact I know so much of them that I have changed many of them for sand filters filled with Zelbrite, and heartily discourage anyone from buying one and to choose instead something that is far less expensive, far less prone to malfunction, and far easier to maintain. Zelbrite has filtration properties almost identical to those of D.E. plus a couple more. It almost never needs changing, and sand filters do not need the messy addition of D.E. powder of the expensive, regular replacement of grid elements.

I have no particular agenda in recommending one system over another apart from practicality, performance, and cost. My business is to sell whatever the customer demands. The advice based on the experience of a long-time professional who is acquainted with all systems may however carry more weight than that of a one-off report from an end user who has never made any side-by-side comparisons.

i frankly don't understand why some brands are continuing to manufacture D.E. filters. Perhaps until they have amortised the cost of the plant, after which they will drop such equipment from their catalogues. Nowadays there are very few serious arguments in favour of D.E. - except of course for the makers' marketing hype.
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Re: Changing filter media in pool filter - how often

Postby Greenside » Mon Oct 28, 2013 7:35 pm

Our pool is now built and has been filled for almost a week now with no apparent leaks so they are going to drain it and install the equipment later this week. A sand filter was in the original spec but as the contractor asked if they could use a different model of pump, I'm using the opportunity to review most of the components. I was recommended glass beads as a filter medium which, as I understand it, go in the same equipment as a sand filter but are longer lasting and more efficient.

Your thoughts?

Image
Pool during testing last week
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Re: Changing filter media in pool filter - how often

Postby jazzman » Mon Oct 28, 2013 7:54 pm

Sand filters:
What you are probably referring to as 'glass beads' for pool filters, is crushed, recycled glass (or silicone dioxide, to give it its chemical name). That's why when you look at it closely the grains are mostly a mix of brown, green, and white. It's actually quite good, but its claims to near D.E. performance have been eclipsed by Zelbrite™ (a volcanic product , Zeolite, from Australia) which is also cheaper.
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Re: Changing filter media in pool filter - how often

Postby Greenside » Mon Oct 28, 2013 8:06 pm

Many thanks, Jazzman. I've got the pool guy pricing the glass beads and will have him do Zeolite as well. Any idea if there is a supplier in Chiang Mai?
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