Hot Tub Filter Repair and Maintenance page 2

4. Clean / Replace) the Cartridge Light debris can simply be hosed off, but examine inside the pleats of the cartridge. Dirt and oil have a way of accumulating in there. Never acid wash a cartridge. Acid alone may cause organic material to harden in the web of the fabric, effectively making it impervious to water. Soak the cartridge in a garbage can of water with trisodium pq phosphate (1 cup per 5 gallons, or 250 milliliters per 10 liters) and muriatic acid (1 cup per 5 gallons, or 250 milliliters per 10 liters). About 1 hour should do it. Remove the cartridge and scrub it clean in fresh water. Don't use soap. No matter how well you rinse, some residue will remain, and you will end up with suds in your hot tub!

5. Reassemble and Restart Reassemble the filter in the reverse order from which you disassembled it. Open the valves to allow water to flow back into the filter. Check for leaks around the lid clamp. If any appear, go back over steps 2 through 5 and be sure the O-rings or gaskets are properly seated and free of debris and that the clamp is tightened adequately. If leaks persist, review the leak repair procedures described below. When everything is reassembled and free of leaks, restart the pump and bleed the air from the filter through the air relief valve. Add more water to the hot tub if you have partially drained it during the cleaning process.

It's a good idea is to buy a hot tubre cartridge so you can install it and soak the dirty one at your convenience. Replace cartridges when they just won't come clean, when the webbing of the fabric appears shiny and "closed," or when the fabric has begun to deteriorate or tear.