Buying guide for best pool sand filters
A pool sand filter is a popular choice for both home and commercial swimming pool owners. These filters are generally cheaper than cartridge-based alternatives and have lower overall maintenance costs.
While there are lots of good reasons to install a pool sand filter, it’s worth looking at the other options and their relative pros and cons, too. If you decide to purchase a pool sand filter, there are a number of technical aspects to consider. Each is important in ensuring you get the right level of performance and top value for your money.
Helping you get the information you need is exactly why BestReviews was created. We’ve been looking at the specifications of all the latest pool sand filters so we can give you a straightforward but comprehensive buying guide. If you’re ready to buy, one of our recommended models might well be what you’re looking for.
Key considerations
Filter type
You have three main choices when it comes to pool filters: diatomaceous earth (DE), cartridge, and sand.
DE filters offer the highest level of filtration, but it’s an expensive option and demands more time for maintenance. There are also health concerns surrounding the type of diatomaceous earth used in pool filters. It’s a severe irritant if inhaled or if the dust gets in your eyes. Some sources suggest that it’s carcinogenic. While others disagree, it’s not something we would recommend.
Cartridge pool filters have a large surface area thanks to their pleated material. In general, they can filter out smaller particles (10 to 15 microns) than sand filters, thus making your pool water cleaner. However, the differences are rarely noticed.
On the downside, if the water pressure isn’t carefully controlled, particles can be forced through the filter material. Slow flow rates are recommended for best performance, so these filters don’t work well in a large pool. And while cartridges can be cleaned easily, often simply by rinsing with a hose, they need to be replaced more often than sand filters. Cartridge filters cost considerably more, too.
Sand pool filters are usually cheaper to buy than an equivalent cartridge model. Many are more compact, too. They are mechanically simple, so most are very durable. Regular cleaning is simply a question of backwashing, which is easy and takes just a few minutes.
On the downside, they don’t filter particles quite as small as cartridge filters (20 to 40 microns), and some water is wasted when you backwash, so you might have to top off the pool and occasionally rebalance the chemicals.
In summary, cartridge filters cost more to buy and maintain, but there’s no doubt that if they’re running properly, they take more debris out of the water. The question is whether the difference in filtration is enough to trouble you.
A micron is tiny, roughly 0.00004 inch. To give the difference some context, most pollen is between 20 and 35 microns. Anything smaller than 35 microns can’t be seen with the human eye. Both kinds of filters trap something that size, though neither filter is fine enough for drinking water. It’s a personal decision, but you can see why many people are happy with the cleanliness that pool sand filters provide.
Features
Your choice will depend to some extent on whether you’re doing a complete pool, pump, and filter installation or just replacing an existing filter. If you’re starting from scratch, it’s possible to buy a filter/pump combination, which simplifies the process somewhat. If you already have a pump, you’ll need to make sure that the pool sand filter can cope with the flow.
Flow rate
Flow rate is given in either gallons per hour (gph) or gallons per minute (gpm). To get from one to the other you either multiply or divide by 60. For example 40 gallons per minute equals 2,400 gallons per hour. Most setups are designed to pump the entire contents of the pool through the filter once every 8 hours.
You should know the flow rate of your pump (it’s usually marked on the body), so you can make sure your pool sand filter matches. While it’s not a bad idea to have a filter that’s a little oversize, it certainly shouldn’t be too small. Too low a flow rate means the pump is working harder than it should to push the water through, and that will shorten its life.
Tank size and construction
Size: This is another important factor. You’ll usually see that a pool sand filter has an inch rating that tells you the diameter, which is an indication of the amount of sand it contains. This rating can be anywhere from 12 inches on very small models, through 16 to 24 inches in the middle range, to 30 inches and above for large versions.
Pool specialists caution against trying to save money by installing a model that’s too small, because the filtration will be reduced. The following are general guidelines:
- 12- to 20-inch tank: Under 10,000 gallons
- 21- to 24-inch tank: 10,000 to 20,000 gallons
- 24- to 30-inch tank: 20,000 to 30,000 gallons
- 30- to 36-inch tank: 30,000 to 50,000 gallons
Construction: This is either two-piece (with a seam down the sides) or molded as a single unit. While the two-piece tanks aren’t necessarily a problem, there is a potential weakness in the construction, so many prefer paying a little extra for a one-piece model.
Motor size
This is worth checking, though with power seldom below 1 horsepower, the filters are usually well specified.
Multi-port valves
These are common and offer a variety of functions at the turn of a switch. Exact function varies, so it’s worth making a comparison. It’s common to have six or seven positions, including backwashing, winterizing, and bypass (so if you’re draining the pool the water doesn’t actually go through the filter at all).
Timers
These are sometimes built in but more often an option. They certainly offer added convenience (when running the filter overnight, for example), though in many cases they’re an additional cost.
Aboveground and in-ground
You’ll usually find a pool sand filter described as either aboveground or aboveground and in-ground. The difference in the pool type is straightforward: one requires an external shell of some sort to support the water container, and the other is sunk beneath the ground’s surface. As far as the pool filter is concerned, there’s no technical difference, it’s simply that aboveground pools need a smaller filter/pump combination. Hence, you find aboveground pool sand filters as small as 12 inches, with flow rates of under 2,000 gallons per hour. These devices work just as efficiently as larger models; they’re just designed for smaller pools.
"Check the filter’s water pressure once a week. It only needs a quick glance. If it starts to rise, it’s a good indicator that it’s starting to clog and needs backwashing (cleaning). "
STAFF
BestReviews
Pool sand filter prices
Inexpensive: The cheapest pool sand filters are those for aboveground pools and can be under $100. Those that can also serve as in-ground pool filters start at around $150.
Mid-range: You have tremendous choice between $200 and $500, with a wide variety of reliable models from all the top brands. It’s likely that most pool owners can find what they need in this price bracket.
Expensive: High-capacity filters and filter/pump combinations can push prices to as much as $1,500. Care is needed at this level, because some larger filter bodies don’t include valves, which need to be specified and purchased separately. That said, few installations of that capacity will be DIY jobs.
FAQ
Q. Is a pool sand filter difficult to install?
A. If you’re a competent DIYer who is comfortable with a bit of plumbing and sorting out electrical connections, there’s nothing very complex, particularly if you’re replacing an existing filter. It’s a little time-consuming, but it isn’t technically challenging. There’s a lot of helpful information available online, much of it from the filter manufacturers. However, if you’re not confident, it’s always better to call in a qualified installer.
Q. Does a pool sand filter need much maintenance?
A. No. Backwashing (a simple job that briefly changes the direction of the flow) flushes out most of the collected debris and is done every few weeks (depending on pressure buildup). Changing the sand should only be required every few years, depending on the pool type. This is just a general guide. It’s important to check your owner’s manual and adhere to the manufacturer’s recommendations to ensure your filter works efficiently for a long time.
Q. Is the type and quantity of sand important?
A. Yes, though there’s understandable confusion between silica sand (which is widely recommended) and zeolite products (which are often suggested as an alternative). The problem arises because zeolites typically take up twice the volume (so you only need half the amount). For example, if a pool filter normally uses 150 pounds of silica sand, you’d only need 75 pounds of zeolites. Yet despite having bigger granules, zeolites are claimed to offer better filtration of fine particles and dust, which is why they’re popular.
It’s important to follow the advice of the manufacturer or pool installer (if you use one). Given how infrequently you change the sand, any savings won’t be huge, and using the incorrect product or quantity will reduce the effectiveness of the filter and might even cause damage.
