Shut off the water before the filter and leave the softener alone.

Open a faucet in the house to relieve the water pressure in the system. The red button should also relieve the pressure but I prefer opening a faucet.

Unscrew the blue canister counter-clockwise (looking at it from underneath). Remove the old element and clean the inside of the canister and dry. There may be a filter wrench lying around that looks like this picture.

Replace the filter element with the same style and specification element. If you can't identify the element a water treatment store can if you take it to them. Buy one to use and one to have as a spare.

There's an o-ring that seals the canister. Lubricate that o-ring with FOOD GRADE silicon grease. Do not use any petroleum product to lube that o-ring. Good idea to buy a spare o-ring.

Screw the canister back in till it bottoms and hand tighten only. Close the faucet you opened and turn on the water. Inspect for leaks.

thanks for the clear explanation.

So is a replacement o-ring specific to that model filter or can I take it down to the hardware store and match one up?

Silicon grease as mentioned, thats just a tube or cannister of plumbers grease like you would use on a faucet right?

If you can match ip the o-ring then that's fine.

Silicon plumber's grease for potable water (food grade).

So long as the o-ring is undamaged, replacement is not necessary. I have one that has been in use for 20 years. Before replacing or cleaning the filter, I fill two 5 gallon buckets with clean water and use that in a smaller bucket to wash all the reusable components before reinstalling them.

The best way to insure that the o-ring is doesn't need to be replaced is to lube it with silicone grease and to have a spare o-ring in your toolbox .

Thanks again, I swapped it out today. You should have
seen the old filter. It was oozing with rust, disgusting.

Picked up a tin of silicon grease and some replacement o-rings.... was able to use the old one though for now.

Still now identification whatsoever on my model, lucky there was one replacement filter here so I know what kind to get:

Purtrex PXC05-20

hopefully I can find these locally, cheap.

NOw the question is, how long between filter changes?

"NOW, the question is, how long between filter changes?"

The way you KNOW for sure is to look at the pressure gauges the installer should have put before and after the filter so you could see the pressure drop across the filter. When there is a 10-15 psi difference before and after the filter it is time for a change.

But, there's no gauges to look at so you have to take a look and decide. Inspect the element after one month and then after two months and so on. when it looks like it's coated time to replace. Don't wait till it's plugged. Then replace the element routinely at that interval.

If you know a plumber or ever have on in to do a job ask them to add a pressure gauge before and after the filter. It is worth the money.

Find a place to buy the filters 6 at a time to get the price down.
That's the downside of inline filters... constant maintenance.

WAIT A MINUTE... in your other thread you said you are renting for $20 a month and that includes service calls.

Why are you changing filters if service calls are included in the rental price?

Have them come and change the filters and they should be providing the filter elements.

Thanks justalurker for your through explanations. Good eye too about the rental. The filter isnt part ofr the rental, we own it.

So judging by the crud in the filter, I am assuming its in place not just for "taste" rather as a sediment trap (rust) that would otherwise screw up my fittings. I guess my idea of installing a basic one under the sink instead and getting rid of the whole house in line filter isnt a smart idea.??

Purtrex PXC05-20 is a 5 micron sediment (dirt) filter not a filter for taste. With a filter filtering dirt particles that small it will be changed frequently and will restrict water flow and pressure as it packs with sediment.

If you have a sediment problem than a backwashing sediment filter (like a softener in appearance) might be prudent in the long run. As you are now, when the filter restricts water pressure and flow the softener can not regenerate correctly and you'll get hard water leakage.

You have compound problems and require more than a simple solution. There is no magic bullet.

You need to do what I recommended in your other thread and get the water people out there to prove to you that you are getting soft )ZERO hardness) water all the time till regeneration. Ask them about your filter.

There's no more anyone can do for you until all the details of your water supply, water quality, and water treatment hardware are posted.