Does sand wear out?

[Bama Rambler]

My supposition on why mfg's recommend changing the sand every 3 to 5 years comes from the pool store practice of having people add stuff (clarifier, floc, etc.) to their pool and not backwashing well enough allowing the sand to become "gunked" up and channeled. It's much easier to tell people to just change the sand. I'm sure it comes from years of experiencing customers complaining about the filter not filtering and they figured out that the sand being coated and channeled was the major cause of the problem.

I'd be interested to see what Hayward says about it if they say anything.

 

[UnderWaterVanya]

Science good!

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[y_not]

Corporate propaganda baaadddd!!

 

[Swampwoman]

Bama, that actually makes perfect sense to me. I'll keep you posted.
Cheers,
SW

 

[bobodaclown]

Short answer is NO. Having said that, the sand may gum up, pack, or channelize. It does require some maintenance and there are ALWAYS exceptions to the rules.

 

[Swampwoman]

Okay, so even before I write to the, this is what their FAQ says in a couple of references:

Why is the filter continuing to run at high pressure even after backwashing?

Make sure you are following the instructions in your Hayward owner’s manual. The sand bed may be clogged with mineral deposits or other material that will not backwash away. Some calcium based chlorines and other alternative sanitizers could cause a build-up in your sand bed. You may need to change the sand.
Before you change the sand in you filter, try removing approximately 1” of the top layer of sand, and replace with the exact amount of sand removed. This sometimes rids the sand bed of the deposits clogging the filter.

and

When do I need to replace my sand?

On average, sand should be replaced every 3-5 years. This may be longer if the pool stays clear, or shorter, if the filter runs all the time. The jagged edges of the sand wear down and become smooth as the sand ages. When this happens the sand can no longer trap debris particles and dirt can pass through the sand and back into the pool.
If the pool is chemically balanced, the system is running the proper length of time and the bather load is normal, but the water will not clear, even using a flocculant or clarifier, then the sand needs changing.
As the sand ages, it may start to clump and the water flow can form channels in the sand, allowing the debris to pass through. Channeling is often seen when the pump horsepower is too large and wants to move too much water through the filter.

 

[SebringDon]

Okay, so even before I write to the, this is what their FAQ says in a couple of references:

One of the things I've learned here is that many in the industry are either sorely lacking in specific knowledge when it comes to pool maintenance, or they are intentionally misstating their case to increase revenue. That makes the "appeal to authority" logical fallacy pernicious. I think the science is in and the quotes you included simply reinforce that perception to me.

 

[RobbieH]

I changed my sand last year, only because my filter failed and I wanted to replace everything at once. The filter and sand were installed in 1989, the previous owner left receipts. The filter still worked perfectly fine until the laterals cracked. That's 22 years of service on one filter and sand installation on a large pool.

 

[chem geek]

One of the things I've learned here is that many in the industry are either sorely lacking in specific knowledge when it comes to pool maintenance, or they are intentionally misstating their case to increase revenue. That makes the "appeal to authority" logical fallacy pernicious. I think the science is in and the quotes you included simply reinforce that perception to me.

+1

 

[y_not]

I changed my sand last year, only because my filter failed and I wanted to replace everything at once. The filter and sand were installed in 1989, the previous owner left receipts. The filter still worked perfectly fine until the laterals cracked. That's 22 years of service on one filter and sand installation on a large pool.

YEEEAAAHHH!! That's totally awesome!! No water quality difference in the old one (filter+new sand) vs. the new one, I presume?

Okay, so even before I write to the, this is what their FAQ says in a couple of references:

Why is the filter continuing to run at high pressure even after backwashing?

Make sure you are following the instructions in your Hayward owner’s manual. The sand bed may be clogged with mineral deposits or other material that will not backwash away. Some calcium based chlorines and other alternative sanitizers could cause a build-up in your sand bed. You may need to change the sand.
Before you change the sand in you filter, try removing approximately 1” of the top layer of sand, and replace with the exact amount of sand removed. This sometimes rids the sand bed of the deposits clogging the filter.

I could see this, this one seems quite logical. Considering the "junk chemicals" and "magic soups" that a larger part of the industry instructs people to use in their pools.
Also, if that sand had really "worn down", then replacing the top layer wouldn't work. DUH!

When do I need to replace my sand?

On average, sand should be replaced every 3-5 years. This may be longer if the pool stays clear, or shorter, if the filter runs all the time. The jagged edges of the sand wear down and become smooth as the sand ages. When this happens the sand can no longer trap debris particles and dirt can pass through the sand and back into the pool.

This is the key here, they seem to think that the sand filter is a "rock tumbler", of which it is not.
It's a compressed bed! Seldom moving.

If the pool is chemically balanced, the system is running the proper length of time and the bather load is normal, but the water will not clear, even using a flocculant or clarifier, then the sand needs changing.

Wait, if a flocculant doesn't even clear it, isn't that kind of contradictory? Not that I'm saying flocculants are AWESOME or anything. That just sounds funny to me. That's like blaming algae on the filter.

As the sand ages, it may start to clump and the water flow can form channels in the sand, allowing the debris to pass through. Channeling is often seen when the pump horsepower is too large and wants to move too much water through the filter.

Aaah, this is where the reeeeaaalllll truth comes out. Hidden inside that paragraph.
If it's channeled and clumped, well then..... *points finger in air* JUST REPLACE IT!!
Surely that's the solution, YEAH?
Hello??? Try breaking it up and hosing it out 1st. Then if it's still wonkers, replace it. But if you find damaged laterals, or something else when you dive in there. Fix it and put the old sand back.

Unless it's icky and can't be cleaned.
I think that's the key here, the sand can get so raunchy in some situations that it's just not feasable to clean it. So replace it. Doesn't mean the sand is "worn down", it just means it's too gummed up. If you send that sand off, with all the other rescued pool sand, to be cleaned in a plant that does that. Guess what? It'll be juuuust fine!
In fact, they should do that, they should recycle it, have collection stations for that purpose. Then, once the sand is cleaned up, they should sell it at a cheap rate as recycled pool sand.
Makes perfect sense!! But I'm kinda a hippy too.

 

[chem geek]

Channeling in a sand filter is most often caused by bacterial growth forming biofilms. It has nothing to do with the roughness/smoothness of the sand or any "wear" over time. There are strong surfactants on the market designed to get rid of biofilms and/or to prevent them. You would add these to the sand filter on occasion, but in practice this is only needed for higher bather load situations such as commercial/public pools. Residential pools rarely get enough organic material to have significant biofilm channeling problems. We've got thousands of pool owners with sand filters and I only recall one or possibly two that had channeling and those cases could be explained by the improper maintenance of active chlorine levels that had occurred prior to coming to this forum.

 

[UnderWaterVanya]

Richard, what about too much pump for the filter? Is that another time when channeling may happen?

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[chem geek]

I'm not sure if an oversized pump would cause channeling per se, but it could cause material to be pushed through the sand bed and back into the pool.