Here’s a message from a conversation I was having
@MDguy.
Our environment is very clean. Not a lot of debris gets blown or carried back into the box. That said, some does, and it accumulates over time. I have probably cleaned my pit once in 9 years and it probably needs it again now. Thanks for the reminder! So with low debris, 3-5 years isn't unusual. Others could see it need cleaning every year if leaves and debris are blowing in, or being carried in on a cover that is not cleaned prior to closing it. What I'm referring to there is that when the cover pump is on, water accumulates around it, and so do leaves and worms, etc. If you just lift the pump off and open the cover, that stuff ends up in the pit. I always take a leaf net and scoop of what is remaining and toss it prior to opening the cover.
Do I like the walk-on lid? Yes, very much. Our stones are 12" wide. And the brackets are probably extended (they are adjustable IIRC) to 11". Would you want a 300 pounder diving off of the lid, no. There could be some tipping of the stone with significant weight on the edge, depending on the weight of the stone and the amount of overhang.
Covers can be sort of a complicated concept if you haven't seen them in action before. At least when you get down to the nitty gritty of using them day in and day out, the safest/best way.
Additionally, I did put a lining of sorts on the bottom of the pit. The bottom is rough concrete in our case and would (did) scratch the cover a bit when new. The cover doesn't wrap tightly against the drum, at least on the last, or last few wraps. So it can drag on the bottom. I put that industrial or garage type of mat that has circles of about 1 - 1 1/4" in diameter. It comes in 3' x 3' matts with grooves at each 12". I cut them in 3' x 1' strips and lined the pit. When I clean it (all one time so far), I reach in and grab them all out to rinse them and rinse out the pit to the 4" drain at the end opposite the motor.
