I purchased a bucket from Walmart that fits the Grit-Guard completely to the bottom. It may have a 1/4" space between guard and bucket. It is blue in color and manufactured by Encore for a price of $2.58.
I'm talking about the screw top lids that you can purchase at homedepot. If you don't have them they are available without having to go online and purchase them. I wish they sold the bucket dolly. Grit guard and autogeeks are asking alot for a two bucket system. I may eventually break down and get the two dollies with the diamond plate attachment.
I actually took my grit guard in to homedepot and did test fits until I found one that the guard went all the way into. Some buckets were tight other were just right.
I don't see why you guys use a grit guard or even two buckets........just like the rinseless method, put 6-7 microfibers in the bucket and use them one at a time to do a single or two panels, then just discard them for the wash. That way your solution stays 100% complete virgin with no dirt in it, and you have no need for two buckets or a grit guard. It works very well