Why is it important to figure out what the make and model of your filter? Because filters get old, break, or need replacing. To find the right part for your filter, you need to know what you have. So, let us start with the easy things first.

### Filter’s Information Tag

Every pool filter comes with spec and model information sticker on its tank. This sticker lists the make and model, the list of sizes for that particular model, and their specs.

The model number of your specific unit should be marked. The label should also list a serial number. If the only thing legible on the label is the serial number, you can contact the manufacturer to have them identify your filter.

### Use the Filter’s Dimensions to Narrow Your Choices

The filter model is usually marked on the manufacturer label by the maker or the installer when it is first put in. If the filter lists the model sizes but no mark is made, you can use the filter’s dimensions to narrow down your possibilities.

##### Sand Filters

In the case of sand filters, calculate the tank diameter. There are a few ways to calculate the diameter of the tank: measure the circumference, then solve for the diameter, or two yardsticks and a measuring tape can be used.

First, measure the circumference of the widest part of the tank, then use this simple formula to determine the diameter:

#### C=πdC​ = circumference, π = 3.14 and ​d​ = diameter

Secure two yardsticks on the opposite sides of the widest part of the tank, then calculate the distance between them in order to use the stick and tape process. With the measuring tape, you are basically making goalposts and building a crossbar, which should give you a precise diameter.

##### Cartridge Filters

Take out the cartridge for a cartridge filter to measure the length and width of the plastic end cap (end cap to end cap, not including the spout/tap used on certain models of cartridges).

Cartridge Part Number on Endcap

##### DE Filters

For DE filters, to classify their size, calculate the length of the curved grids. The grids come in 5 different sizes of 24, 36, 48, 60, and 72 square feet, with lengths of 12, 18, 24, 30, and 36 inches respectively.

You would need to calculate all grids for older models like the Jacuzzi Earthworks and Avalanche, which use non-curved grids because a mixture of two or three grid sizes per model was used for the different model sizes.

### Use Internal Part Numbers to Narrow the Possibilities

Sadly, due to exposure to the sun and materials, model tags fade over time. You may use the part number of an internal part such as a lateral, manifold, or dirt-catcher to decide which family of filters yours belongs to if your tag is bleached out. The exact model you own would probably not be defined by this information because manufacturers prefer to use one component on a couple of different models.

You can check it in Inyo’s part finder to pull up a match when you find a part number on one of these internal bits. The product page will list the model(s) used if we carry the section. You can then display these diagrams of components to decide which is most similar to your model.

If you have any other questions about pool and spa products please do let us know - we are here to help!