1. Should I take out my cartridges or leave them in the filter through the winter?
2. I have a heat pump (Heat Siphon) and I noticed a little standing water in the bottom. Is there any danger from this freezing? Should I just pour a little RV antifreeze in there to be safe?
3. My water level is currently below the jets. I have a mesh cover. Now over the course of the winter, I expect rain and snow meltoff to bring the water level up over the plastic parts. This is my first closing, but I opened last year and the water was around normal summer levels, so I'm guessing this is what happens over the winter. I feel I've done everything correctly as far as the skimmers and lines go. Would I be safer or just wasting my time if I checked the water level every 4 weeks or so and drained it below the jets again if it was coming up?