Sand filters are the most common pool filter in America, and one of the easiest to operate.
Filter sand is also very common, but not the easiest filter media to replace.
If you are wondering about why, what, when and how much filter sand, you are in the right classroom!
Why Change Pool Filter Sand?
- New filter sand has sharp, crisp edges that stack well into layers. Old sand has rounded edges that don’t filter the water as well.
- Oily dirt, dead algae, and other gummy residues build up and are pushed deeper into the sand bed with each backwashing.
- Small amounts of sand can be lost during backwashing, and over many years time, can add up to a considerable loss.
When to Change Pool Filter Sand?
This depends on the size of your sand filter in relation to the pool, but somewhere between 2-7 years.
Small sand filters of 16″, 18″ or 21″ diameter need to replace the sand more often, every 2-5 years, sooner if the pool is used heavily, or has sticky tree debris, or a pump that is too large for the filter size.
Larger sand filters with 24″ to 36″ diameter tanks can often go longer between sand changes, simply because of the larger filter area. 5-7 years is the normal interval for larger sand filters.
The best time to replace filter sand is before you need to, but… if you notice poor water quality, short filter cycles (time between backwashes), or dirt passing through the filter, it may be time to replace the filter sand.
What Type of Sand for Pool Filters?
Our help files have stories of some who have inadvertently added the wrong type of sand to their pool filter. Masonry sand or Play sand won’t work in a pool filter, use only a high quality Pool Filter Sand.
Our help files also have a few entries of folks who purchased a cheap product ($5) labeled pool filter sand, that turned out to be a very poor substitute. Buying a well known brand of pool filter sand from a pool retailer you trust may make a difference in the quality and cleanliness of the filter sand you buy.
How Much Sand to Add to Pool Filters?
Sand filters are not filled completely full of sand, but only about 2/3 full, to allow “Freeboard” space in the tank, above the sand bed.
Your manufacturer will list the amount of sand required on their website, usually on the brochure or spec sheet, or you can find it with a quick google search with your filter make/model.
Or, you can refer to the pool filter sand chart here. You need to know the tank diameter, which is often reflected in the filter model number, or can be found on the manufacturer spec sheet. Or you can measure the tank with a ruler.
How to Change Pool Filter Sand?
How to actually change the filter sand – that’s a whole ‘nother topic that we’ve talked about here, and also here.You may be interested in a post I wrote about how to improve sand filtration or information about pool filter sand alternatives like ZeoSand or FilterGlass.
That’s all for today students, class dismissed!