Why do I need to change my pool filter sand? Doesn’t sand last forever? Well, the answer to that is yes and no. Yes, sand basically lasts forever but over time, it loses its potency as a filter media. To the naked eye, the sand used in sand filters look just like any old regular sand out there. But under closer inspection, you would find that the grains of sand are actually rough and textured. This roughness is the component that provides the filtering component. The tiny bits of dirt, algae, dead bugs, and other contaminants gets snagged by the tiny burrs on the sand and clean water passes on through.
Over the years, this texture gets smoothed out due to the amount of water passing through. To illustrate this point, try walking down a beach or a stream, notice how almost all of the small rocks have smooth surfaces? This is called weathering. The surfaces of the rocks (and in our case sand) gets smoothed out over the years, and while you’re left with nice smooth sand, it’s useless as a filter media.
How often do I need to change pool filter sand?
Depending on the usage, pool filter sand can go for years without needing a change. Here are Mr Pool Man, we recommend that you absolutely change your filter media sand at the very least three years and at seven years at the latest. This will not only ensure that your pool water is filtered optimally, but this keeps the stress on your entire pool system low as well. The best way to tell if your sand filter media is nearing the end of its lifecycle is that your pool may cloud up more often and you’ll notice that you’re shocking your pool more often than normal.
Can I just use any old sand for my pool filter?
Absolutely not. Don’t even try to use regular sand in your sand pool filters because at the very least, it won’t filter your water, but what’s most likely to happen is that it will destroy your entire filtration system.
Types of Sand Filter Media
There are basically three different types of sand filter media that is available out there depending on your needs. Here’s a basic rundown of the different types of filter sand out there.
This is the most commonly used sand filter media. It’s affordable and it lasts for years. This is made from ground quartz that’s around 0.45-0.55mm in size. The grinding process creates the silica sand grains with jagged edges that makes it the perfect filter media for trapping contaminants in your water. This is usually labelled as “Premium Filter Sand”.
Although many media filters come with regular silica sand as their initial load, when replacing media filter sand, it's better to go with glass sand media. For a nominal cost, you can enjoy clearer water, less backwashing, and it is actually lighter by weight (meaning you'll buy less). Plus not only that, but it's already compatible with magnesium pool setups!
Glass sand filter media comes in two grades, coarse and fine. The coarse grade of glass sand media is usually 1.7mm to 3.4mm in size and is used to cover the under drain and laterals of your sand filter and this grade usually comprises of 30% of your glass sand filter media requirement. Fine grade glass sand is then layered on top of the coarse grade glass sand to complete your setup. Glass sand, while more expensive than your regular silica sand, works much better. It requires less media (by weight) to fill up your sand filter, uses less water than backwashing, relieves pressure on your pumps by providing superior water flow, and it lasts much longer than your traditional silica sand.
Other Sand Media Alternatives
There are other newer sand media alternatives out there which claim to be better than sand glass sand media but until we see real evidence (not just marketing hype) of the media being used for years, we’re holding our judgement and sticking to tried and true silica and glass sand media.
Glass Sand Media Ratios:
Unlike silica sand filter media where you just fill it up, glass sand has a ratio so it’s good to know how much of which grade to buy depending on your filter size.
- 21" Sand Filter - 60kgs
- 25" Sand Filter - 100kgs
- 28" Sand Filter - 160kgs
- 32" Sand Filter - 280kgs
- 36" Sand Filter - 360kgs
Step-By-Step Guide to Changing Pool Filter Sand
Now that you know about the different kinds of sand filter media, it’s now time to get into the heart of the problem. Changing your pool filter sand.
Turn off the filter and pump. This is important as you don’t want the pump to roar into life while you’re in the middle of changing the sand in your media. To be totally safe, turn of the breaker for your pump and unplug everything totally.
Drain the pool filter by removing the drain plug from the bottom of the filter tank and let the water drain out naturally.
Remove the hoses or pipes that are attached to the multiport valve so you can access the tank itself. If you have unions installed, this should be straightforward. If the pipes are hard-plumbed into the valve, you’ll have no choice but to cut the pipes to remove the valve. If you’re cutting off the pipes, it would be a great idea to install unions so that the next time you replace your sand, it should be as easy as twisting off the union to remove the plumbing.
Once the plumbing is removed, give it a gentle twist and the multiport valve should come off quite easily.
Once the multiport is off, you should see the standpipe in the middle. Cover with some duct tape or cloth fastened with string to prevent sand from entering it. If sand enters the standpipe then it’s going to get flushed into the pool, wasting water in the process.
Carefully scoop out the sand with a plastic cup. Yes, this can take a long, long, time. Alternatively, you can use a shop vac or a wet and dry vacuum to suck out all of the sand. If you don’t have a wet and dry vacuum, bring a cold beer to a neighbor who has one. It’ll save you hours of backbreaking scooping labor. Another option to easily remove the sand from your pool is to use a Venturi Pump, a V-Pump can drain out all of the sand in no time at all (and save you a beer so you don't have to borrow a vacuum from your neighbor). Not only that, V-pumps don't need as much cleaning as wet and dry vacuums, just rinse them out afterwards and you're done.
Once you’re able to see the laterals sticking from the stand pipe bottom, the sand should be all but gone. Give it a through rinse with a garden hose and the remaining sand should exit via the drain plug you removed earlier.
Visually insect the inside of the filter tank for any cracks and damages. If you find any, patch them up or consider replacing the sand filter tank to avoid any emergencies down the line. Once you’re satisfied that everything is in full working order, reattach the drain plug and fill the tank about halfway with water.
Once the pool filter tank is half filled with water, you can now start filling it with sand. Remember to make sure that the cover we attached in step four is tight and secure, you don't want sand to get into the stand pipe. The water is there so that the falling sand will be cushioned by the water and laterals won’t get damaged by the weight of the falling sand.
Note: Wear a mask and ask a mate to help to hold the stand pipe in place until the laterals are fully covered with sand.
Once all of the sand is inside, fill the tank with water and reassemble the connections to your pool filter. Make sure to remove the covering from the standpipe before reattaching the multiport valve. Make sure all of the fittings sit flush and secure to avoid any leaks and accidents from happening.
Backwash and rinse the filter to get rid of any excess sand in the system.
Once backwashing is done, run the filter and check the pressure valve. This is your pool filter’s normal / optimal running pressure. Write it down (I use a sharpie and some duct tape and stick it to the side of the filter) for future reference. If you see that the pressure is about 10 PSI above the optimal running pressure then that’s a good sign that you need to backwash the filter.
That’s it! You’ve successfully changed you pool filter sand! You won’t need to replace them for a few years again with proper backwashing and maintenance. Be sure to bookmark this page so that you'll have a handy guide the next time you need to change your pool filter sand.
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Happy swimming :)