Questin About Laterals in a Sand Filter

[Pointyhead]

Since I'm new to this pool stuff (heck, we haven't even closed on the house yet) I'm just learning all I can about everything related to keeping it up. I am an old aircraft mechanic and I always want to know exactly how things work, so I will know when they don't.

OK, inside a sand filter, the laterals are what collects the cleaned water from the bottom and redeposits it back into the pool, but what exactly keeps the sand out of the laterals and going back into the pool? I would think that they have some sort of fine mesh a few microns large to keep the sand at bay. If this is so, what is the purpose of the sand? Not having a lateral handy, and I can't locate a good picture of one on the web, I am deferring to the experts-you!

 

[JasonLion]

99% of the answer is that it works, so no need to worry about it.

Most laterals have slots instead of mesh, but it is the same idea. Using sand gives you a vastly larger surface area and since the sand grains can move apart any debris can be washed out easily, while debris would get caught in the "mesh" and some of it would be impossible to remove.

 

[Icehawg]

Welcome PointyHead.

This post, a few back, shows two pictures of my laterals and assembly if you want to see what they look like.

filter-sand-excreted-during-rinse-t45533.html

 

[Pointyhead]

Thanks, Icehawg. Great pictures, and I can zoom in on them to see what I had suspected-that the slots are small enough to let the water molecules enter, but not the grains of sand.

Not for the age-old question, does the sand ever wear out? Searching the web, I can find all kinds of opinions about the subject, but there's no empirical evidence from any one that shows difinitive proof that the sand wears out, just anecdotal stories about it.

You would think one of the pump companies would get some hard evidence one way or the other.

 

[JohnT]

The sand will probably eventually wear out, but it's likely you'll need to get inside the filter to do something else long before that happens.

Often, people use so many additives in their water that the sand gets sticky and channels form through it which reduces its filtering ability. Changing the sand fixes it, so they assume it was the sand. You can stick a hose in it and churn the sand around and fix it too.

 

[Bama Rambler]

There are some microscopic pictures on the site of new sand and sand that's several years old and you can't tell a difference. Like JT said, you're going to have to tear into it for some other reason way before it actually wears out. Think about it this way. The same sand has been on the beaches for millions of years being pounded by the surf and it isn't wearing out.