Best way to store H2O filter and plate chiller?

I have been using a whole house water filter with cpvc connections to attach to garden hose and outlet tube that 90's down almost the height of the filter housing.

If used in designed capacity it would have water in it constantly. I'm wondering if leaving any water in and the lid tightly closed will lead to mold/mildew issues. I've taken to removing the top and pulling the carbon filter out so it can dry and not be enlcosed with water.

Also have a new (to me) plate chiller. Boiled it for about an hour while I cleaned the last of the bottles from before I started kegging. After the water cooled to around 150F I dumped some PBW in and let it soak for a few hours. Rinsed the outside and then attached hose to rinse the wort side areas. Ran water through forward and backwards to thoroughly rinse. Drained well.

Now, am I wasting my time opening the water filter? Once I use the Schirron plate chiller, I'll rinse well and sanitize prior to use. But are there any other steps I should take and will it be ok in a garage that gets below zero here sometimes in Denver?

It is a very good idea to dry out your filter. Under normal use, there would be frequent flows through the filter, not stagnant water.

I take mine apart. A pain yes but better than using mold to help filter.