The Best Grit Guard
Grit Guard Analysis
The purpose of a Grit Guard is to keep contaminants down in the bottom of the wash bucket so that they cannot be recaptured by a wash mitt and then rubbed on the clear coat and cause damage.
I believe the Detail Guardz Dirt Lock is the best device for doing this.
From a performance standpoint, the Dirt Lock was clearly shown to be extremely effective at keeping contaminants at the bottom of the bucket and not letting them back through. The design of the filters using the venturi effect to channel the water flow down and make it very difficult for things to flow back up worked excellently and even in the food dye example, managed to maintain a higher concentration of the coloring beneath the guard, showing how it effectively traps whatever is beneath it.
From an ease of use perspective, the Dirt Lock was not the easiest to use, but was better than the Dirt Trap. The foam tabs help make a snug fit in almost any bucket and even if it is tightly wedged into the bottom, the finger holes around the center make it much easier to pull out than something like the holes on the dirt trap which offer no real grip at all and I had to use pliers to get out.
The Chemical Guys Dirt Trap is good at keeping contaminants down, but was just not nearly as user friendly thanks to its lack of grip to pull it out if it gets stuck in the bottom of the bucket. I would not worry about contaminants if this was in the bottom of my bucket.
The original grit guard was very disappointing. The mesh design did hardly anything to stop the flow of contaminants back up into the top part of the bucket. Maybe if you used a very tall bucket this would be enough just to keep things in the bottom, but if the mitt thrashes the water around anywhere near the guard, it is going to stir the contaminants back up.
I will be doing a part two (and update this) to discuss the ease of cleaning each guard, the ability to help remove contaminants from the mitt and whatever other feedback I get from this discussion and the video.