Hot Tub Filters

How to identify a hot tub filter when the brand page is not enough

Every spa filter is defined by five things, and they are all on the cartridge in your hand: diameter across the end cap, length end to end, the top style (open hole, handle or closed), the bottom style (open hole, male thread, female thread or slip fitting) and the thread size if it threads in (1-1/2″ or 2″, coarse or fine). Manufacturers round these differently — one calls a 4-15/16″ cartridge 5″ — so a 1/16″ to 1/4″ difference between what you measure and what a page lists is normal. A different end style is not.

Our product titles use plain names for these: Drop-In (open both ends, sits in the well), Outside Thread (male thread on the bottom, screws into the well), Inside Thread or Teleweir (female thread inside the bottom, for skimmer weirs) and Open Bottom. Square footage is the pleat area — a bigger number means longer between cleanings, not a different fit.

Which filter brand should I buy?

Most spa brands never made their own cartridges; the same pleated filter is made by several manufacturers and sold under the spa brand’s label. That is why every EZ filter page offers the same cartridge in more than one brand: Hurricane (made in the USA, our stocked value pick), OEM Factory Direct (the spa maker’s own label), ProAqua and Darlly (drop-shipped budget and mid options) and Ego3 (a reusable canister you refill instead of replace). The pill buttons on each product page switch between them and show the price, so you can compare on one screen.

Not sure which filter brand is right for you? Compare Hurricane, OEM Factory Direct, Pleatco, ProAqua, Darlly and Ego3.

Buy the set, not one filter. Spas with two or three filter wells load them up at the same rate; replacing one and leaving the others is why a tub still looks cloudy after a “new filter.” 2 packs and 4 packs are priced below the same number of singles.

Filter care that actually extends filter life

• Own two sets and rotate: install the clean set, rinse the dirty one with a high-pressure nozzle, let it dry completely on the shelf.
• Once a month soak the off-duty set in a filter cleaner solution — rinsing alone never removes oils and lotions.
• Replace pleated cartridges about once a year; sooner if pleats stay grey after a soak, the end cap cracks or the pleats collapse.
• A dirty filter is the number one cause of freeze damage in winter: low flow trips the heater and the water stops moving. Clean filters before the first cold snap.

Keep your filters working longer: High Pressure Filter Nozzle | Filter Cleaner | Water Care — and every order over $99 ships free, so a spare set plus cleaner usually rides along at no extra cost.

Hot tub filter questions