Sand Filter Calculator: How Much Sand Do You Need?

Written by Michael Dean

calculator next to pool filter sand

Pool water must be circulated through the filter to remain clean and clear. The pool pump will push water through the filter media, which is made up of sand, diatomaceous earth, or a cartridge.

If you have a sand filter, it is important to determine how much sand to add to your filter to optimize the effectiveness of the sand. Too much or too little sand in the filter can cause all sorts of problems.

In this article, I will show you how to calculate the amount of sand to use depending on the size of your filter. I will go over some popular filter models and how much sand is needed in each of them.

How to Calculate How Much Sand You Need to Add to Your Filter

The manufacturer of your pool pump will almost always include instructions that will guide you on how much sand to put into your pool filter. But if you are unsure, here are some helpful tips for determining the correct amount.

The two-thirds rule

Most sand filters are designed to be filled about two-thirds of the way. This allows for a bit of space above the sandbed, but still catches all the water flowing through it. This is a good basic rule to follow, but it is still good to know exactly how many pounds of sand your sand filter requires.

How much sand to put in the filter?

Here is a table showing the amount of sand that should be poured in each sand filter size. Make sure to measure the diameter of your filter, so that you can easily calculate how many pounds of sand to add.

Sand filters generally start at around 16 inches in diameter. For a 16-inch sand filter, you should expect to add around 100 lbs of sand. For every inch in diameter larger than 16 inches, you add an extra 25 lbs of sand until you reach 20 inches. From 20 inches, you add 50 lbs for every 2 inches in diameter until you reach 24 inches. From 24 inches, you add 50 lbs for every 3 inches until you reach 27 inches. For every 3 inches above 27 inches, you will add 150-200 lbs. The largest sand filters are generally around 36 inches.

Here is a helpful chart:

Diameter of the TankPounds of Sand to Add
16 inches100 lbs
18 inches150 lbs
19 inches175 lbs
20 inches200 lbs
22 inches250 lbs
24 inches300 lbs
27 inches350 lbs
30 inches500 lbs
36 inches700 lbs

This table will not translate to every pool pump model. Some may have slightly different volumes, and some will require more sand than others. So always check your model’s instructions first.

If doing all that math makes your head hurt, here’s a calculator I put together to figure out how much sand you need to add based on your tank diameter.

What happens if you add too much sand to your filter?

Adding too much sand to your pool filter can cause the pressure in your filter tank to rise and negatively affect the performance of the sand filter. If there is too much sand in the filter, it may cause certain components to break when putting the filter back together.

Always follow the manufacturer’s instructions when adding sand to your filter.

What happens if you add too little sand to your filter?

If you don’t add enough sand to your pool filter, your filter will not filter the pool water as effectively. The dirty water will easily create pathways through the sand or bypass it completely, meaning the sand will not filter out debris and the water will become cloudy.

Common Filter Models and How Much Sand They Require

Here is a breakdown of some of the most common sand filter models on the market and how much sand to put in each one.

ModelSizeLbs of Sand to Use
Hayward Pro Series Sand Filter18 inches150 pounds
Hayward Pro Series Sand Filter21 inches200 pounds
Hayward Sand Master16 inches100 pounds
Hayward Sand Master23 inches250 pounds
Pentair SD40 Sand Filter19 inches150 pounds
Pentair SD60 Sand Filter22.5 inches250 pounds
Intex KrystalClear Sand Filter14 inches77 pounds
Carvin “Laser” Series19 inches150 pounds
Carvin “Laser” Series25 inches325 pounds

Bottom Line

It is common for pool owners to misinterpret the amount of sand needed in their pool’s sand filter. Make sure you pay attention to the instructions and your filter will likely run smoothly and catch all debris running through it. Most filters should be filled about two-thirds of the way, but depending on the diameter of your filter, you’ll need to purchase more sand to fill the filter. Pool filters could need anything from 100 lbs to 700 lbs of sand, so plan accordingly, and your pool will sparkle throughout the season.

More questions about sand filters? Drop me a line or check out some of my related guides below.

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