No doubt you will get a landslide of how to for the ICE!
I put some in the toilet, open the valve, let it slide in (don't put a lot at a time or you may have to get it started) add more until bag of ice is gone.
This past season I bought a clear elbow, short one and had to turn it sideways to hook up since the Pod drain is so low. Then I hooked up the hose ( one that cleans, not water hose) to the elbow. I put water up it, full force, then let it drain. UNTIL what comes out is clear. The gages are not the most accurate. Never had that problem with motorcoach, the gages. When I KNOW it is on empty, by the time I get home it may register with some in it. AND I am not stopping along the way to use it. Dang thing!
My last trip out, gone for 20 days, I put Calgon water softner in with plenty of water, it sat about a week with full hookups, waiting until it was full, dumped, then did the Calgon thing again and let it set until I was ready to dump and leave. After using the little clear elbow, I did Calgon and water again before I left. I also put a cup of low suds Tide in. Next part of trip I was boondocking, so sparing on the use, but it had the Calgon and Tide in it. Did not put ice in that time.
I think someone on the forum has the exact formula of how much Calgon and water.