I'm planning to use my old tank, which is currently removed from the cab and is in pretty good shape.
I plan on using Tiny's route of cleaning it up by throwing in a few short lengths of galvanized swingset chain that I happen to have, with some solvent. I'm pretty confident this will work for me.
I'm not sure what the crystals are in your tank... sand comes to mind. Did it show up in your filter bowl?
I would have to remove the tank and get that mess outa there.
Jerry

1959 Chevy Apache 3200 Stepside
In the Stovebolt Gallery
Restoration Journal on Facebook

"A government that robs Peter to pay Paul can always depend on the support of Paul." ~ George Bernard Shaw