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Thread: Does Sand Wear Down??

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    Does Sand Wear Down??

    If sand from your filter is blowing back into your pool then something in your filter is broken, if you have the model number I can help a lot better. You say you don't have laterals, and you have a screen. Is there any big holes in the screen or tear or an entrance in to the stand pipe where the sand can go in? Make sure the stand pipe isn't cracked and it goes proper into the multiport as it should.

    Some filters have a tube that goes to the stand pipe that attaches to a screen that releases trapped air and if that doesn't have a screen or the tube is gone sand will blow back into your pool.

    The sand does wear down after time and is suggested to replace every 5 - 10 years. If it's as old as your filter it could have worn down enough to pass thru your screens. (That's rare thou).

    If you can't figure it out 40 years is old for a filter and I would replace it with a cartridge filter. They are very efficient and let's water flow thru them better then sand or de filters. Also they are very easy to clean.

    Any questions just ask.

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    Mod Squad jblizzle's Avatar
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    Re: Is this 40 yr old sand filter working?

    Quote Originally Posted by RedBluePool View Post

    The sand does wear down after time and is suggested to replace every 5 - 10 years. If it's as old as your filter it could have worn down enough to pass thru your screens. (That's rare thou).

    Any questions just ask.
    Sand does not wear out, it is millions of years old. There are high res pix on the forum that prove this.

    Certainly the filters should be deep cleaned periodically, we recommend yearly. But, no need to replace sand except in rare instances (like calcium scaling or if gooed up)
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    Re: Is this 40 yr old sand filter working?

    Yes sand is millions of years old. The beaches actully used to be filled with quartz rocks and during the ice age storms, winds and earthquakes from volcanoes casted much of the rocks into the ocean. Then Glaciers would actully travel and move. Even over land. They ended up grinding up the quartz-es under them creating sand. Its an amazing story and hard to believe but that the world we live in. Sand can get worn down, I don't care if you have hi res pictures on this forum. This is my job and I see bad sand and it has to get changed to get the filter working properly. Trust me i'm not just trying to make money off of someone by changing their sand. There is nothing fun about Removing sand from 2 1000lb filters putting fresh chat and sand back into which i had to carry to the back yard. Then remove the excess sand. I don't know one pool technician that likes doing a sand change.

    So please don't try to spread a misconception on here, I want to make sure people get the right information.
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    Re: Is this 40 yr old sand filter working?

    Quote Originally Posted by RedBluePool View Post
    So please don't try to spread a misconception on here, I want to make sure people get the right information.
    If you were right about the sand wearing down then every beach in the world would be filled with tiny round beads, but in reality sand is very jagged and has been for millions of years. You are the one that shouldn't spread misconceptions. If the sand hasn't worn down in a million years, a few years in a filter isn't going to make any difference to it. Besides, sand captured in a sand filter isn't subjected to anywhere near the movement or abrasiveness that beach sand sees, and it's not wearing down to dust in a few years.

    I know it's hard to accept that you've been needlessly changing perfectly good sand all these years. But you really need to wake up and realize that just because you've always done it doesn't make it right.
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    Re: Is this 40 yr old sand filter working?

    I disagree with you. Sand should only be changed in a filter when it is hopelessly clogged from dirt or chemicals being collected, captured and hardened to a point they cannot be removed. If you keep your filter backflushed and deep cleaned, sand never needs to be changed.

    The 20 years or more you leave sand in a pool pales in comparison to the 50 million years ago that you are discussing. Can you provide us a picture of some sand that is worn down? How long does it normally take? 5 years? 10 years. How do you identify it as bad sand?

    Please be careful about your accusations of misinformation. If you want people to get the "right" information, you are going to have to provide something other than words to convince the thousands of us on this forum who believe otherwise.

    Glaciers don't create sand as a rule. Sand is created mostly by water. That's why sand is found at the beach
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    Re: Does Sand Wear Down??

    I'd also be curious to see "wornout" sand in comparison to "not wornout" sand. A simple deep clean is all that is needed.
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    Re: Does Sand Wear Down??

    Wish I had seen this *before* replacing my sand...
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    Re: Does Sand Wear Down??

    im glad this thread is titled agree to disagree,
    i am of the belief that sand does at some point need to be changed, if you consider the mfg. of sand filters
    require us to add [ depending on the model / size ] x number of pounds of pea gravel and x number pounds of # 20 silica sand , or all # 20 silica sand around say 300 lbs , if you rub some # 20 silica sand between your
    fingers & some other sand between your fingers you will see just how " sharp " the silica sand is, and when
    changing this sand 5 , 10 yrs ? if you perform this same test you will see the silica sand has lost the sharpness it once had, is this what cleans & polishes the water ? the mfg. could probably answer this question better than any of us, however at $ 10.00 per 100 lb. bag of # 20 silica X 3 , next time those of you that believe that sand is sand , save yourself some money & get just any old sand you can.
    just my 2 cents

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    Re: Does Sand Wear Down??

    Sand is specifically chosen and graded for size and other qualities. You can't just use any sand.

    That said, sand almost never needs to be changed. In virtually every case, people are considering replacing the sand because they are having a water quality issue that they cannot figure out. However, it's almost never due to bad sand.

    In many cases, it's because the cya is way over 100 and the fc is being kept at 1 to 3 ppm. But they're sure that it's not a chemistry problem because right on the side of their bottle of test strips it say 1 to 3 is "Ideal".

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    Re: Does Sand Wear Down??

    Just once I would like to see some pictures and hard evidence of what bad, or worn out sand looks like. Not one person has ever produced any that I am aware of. I'd also like to know what is done to determine that it is bad. Do they pull a sample and look at it under magnification to see if it is "worn out"? I really doubt this being the case.

    But...where do they get this new sand? Are there places in the world where they don't dig it up because its already worn out by nature?
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    Re: Does Sand Wear Down??

    Sharp edges don't make the filter work. Rather the tight space between particles and smooth particles pack tighter. The sharp edges are proof of sand not wearing out. They are created by silica cracking under stress due to ice which has a lot more to do with making sand from granite than the crushing by glaciers. Glaciers, or rather the climate allowing glaciers, did make the sand but by alternating freezing and thawing not by grinding. I've worked with particle based filters for many years and never once "wore out" the media unless other factors contributed. Think about it- if the sand wore out, it would simply be more similar to de and work better!

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    Re: Does Sand Wear Down??

    OMG did noone here take geology?? smh.

    Pool sand is fine ground silica, in the size range of 0.425-0.85mm diameter. This size range equals the US sieve 20, hence why we say to use silica sand 20 in pool filters. Very fine sand would be 0.0625mm and very coarse would be 2mm.

    Pool filters utilise macrotexture for filtering. Macrotexture is the gaps between the grains of sand. The second way the filter works is bacause the sand grains will build up a surface charge attraction, which will also attract contaminants to the sand and hold them there

    When you backwash, water and air are forced through the sand bed, dislodging larger particles and altering the attraction state, whereby all the trapped particulates are released into the water column and out the backwash hose

    Sand also has a microtexture. This is the texture of each individual grain of sand. This microtexture is not considered relevant to the operation of a sand filter as the microtexture does not really capture any particles. This is why we say sand filters can only filter to 400 microns (0.4mm). Silica sand is considered to be a 'rounded' sand as it has little microtexture, compared with other sands

    Sand will wear down over time. However silica sand is composed primarily of quartz, which is the most resistant rock to both chemical and mechanical weathering.

    When you rinse your sand bed, you pack down all the sand particles as tight as the filter can make it. The volume will be approximately 65% sand, with water making up the rest of the gaps. The water is gradually displaced over time, with debris, you backwash and rinse and the whole process starts over. This packing severely limits the sands exposure to mechanical weathering

    Even so, all the mechanical weathering or chemical weathering would do is break tiny pieces of sand off of each sand grain. When these pieces get too small to be held by the filter they would be ejected via a backwash, constantly lowering the amount of sand in the filter. If weathering was a major player in making your sand go bad or wear out, everyone would be talking about how many bags of sand they have to top up each season.

    All grains of sand start out angular and become more rounded as they are polished by abrasion during transport by wind or water. Quartz grains, however, resist wear. One trip down a river is not enough to thoroughly round an angular grain of quartz; even a long sojourn on a beach, where grains are repeatedly tumbled by waves, does not suffice. The well-rounded state of many quartz sands can be accounted for only by crustal recycling. Quartz grains can survive many cycles of erosion, burial, cementation into sandstone, uplift, and re-erosion. Recycling time is on the order of 200 million years, so a quartz grain first weathered from granite 2.4 billion years ago may have gone through 10 or 12 cycles of burial and re-erosion to reach its present day state. An individual quartz grain's degree of roundness is thus an index of its antiquity.

    I dont think 20 years in a filter is gonna matter one jot to the sand considering its lifetime to get there
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    Re: Does Sand Wear Down??

    If the sand isn't "working", it's probably gunked up with products or another substance.
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    Re: Is this 40 yr old sand filter working?

    Quote Originally Posted by RedBluePool View Post
    Yes sand is millions of years old. The beaches actully used to be filled with quartz rocks and during the ice age storms, winds and earthquakes from volcanoes casted much of the rocks into the ocean. Then Glaciers would actully travel and move. Even over land. They ended up grinding up the quartz-es under them creating sand. Its an amazing story and hard to believe but that the world we live in. Sand can get worn down, I don't care if you have hi res pictures on this forum. This is my job and I see bad sand and it has to get changed to get the filter working properly. Trust me i'm not just trying to make money off of someone by changing their sand. There is nothing fun about Removing sand from 2 1000lb filters putting fresh chat and sand back into which i had to carry to the back yard. Then remove the excess sand. I don't know one pool technician that likes doing a sand change.

    So please don't try to spread a misconception on here, I want to make sure people get the right information.

    Great suggestion!

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    Re: Does Sand Wear Down??

    My 7 year old commercial pool sand turned almost to mud by the end of its life. I replaced it with two stage quartz. My home pool is cartridge so i only have one pool and one tub to compare to. The last filter for my tub exploded so most of the sand went down the drain. I replaced that sand with normal sand
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    Re: Does Sand Wear Down??

    Sand can't turn to mud. That doesn't even make sense.

    And, you can't use normal sand in a sand filter.

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    Re: Does Sand Wear Down??

    I deep clean sand with the filter running in backwash mode. Yes it's wet and dirty, but really the only way to go. I have sand filters 15- 22 years on my route, never changed, run 12 months a year. Pools are fine.

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    Re: Does Sand Wear Down??

    Interesting. My pool guy thought my sand needed to be replaced, it's been 10 years. Also, a bunch of playground sand got into the pool that may be in the sand filter.

    How do you go about giving it a deep clean? For how long?

    Thanks!

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    Re: Does Sand Wear Down??

    Quote Originally Posted by tallen234 View Post
    Interesting. My pool guy thought my sand needed to be replaced, it's been 10 years. Also, a bunch of playground sand got into the pool that may be in the sand filter.

    How do you go about giving it a deep clean? For how long?

    Thanks!
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    Re: Does Sand Wear Down??

    Quote Originally Posted by Patrick_B View Post
    Just once I would like to see some pictures and hard evidence of what bad, or worn out sand looks like. Not one person has ever produced any that I am aware of. I'd also like to know what is done to determine that it is bad. Do they pull a sample and look at it under magnification to see if it is "worn out"? I really doubt this being the case.

    But...where do they get this new sand? Are there places in the world where they don't dig it up because its already worn out by nature?
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