Are you talking about one of these type of brushes? If so, I agree that they are a "must have". Especially for reaching under toe-kicks and edging.
Do you scrub all the grout lines exclusively with a pole brush?
Btw, I went totally ballistic on the last grout job I did a couple weeks ago. The lines where badly stained so I didn't hold anything back.
1. Scrubbed with 20" CRB with white bristles (just for fun)
2. Scrubbed with 20" CRB with green bristles (good results)
3. Scrubbed with 10" CRB with white bristles (best results)
4. Scrubbed and edged with chiseled grout brush on a pole (no noticeable improvement except under toe kicks and edges)
5. Rinsed with spinner
Afterwards, I still thought the grout looked dingy but the client was ecstatic with the results.
(I forgot to mention earlier that in the past I have tried using a weighted Square Scrub with grout pads... no weno).
So far, out of all the different techniques I have used my favorite is still those crappy little 10" Host CRB's. They are light weight, high RPM and work well. Also, for larger jobs you can chain two of them together to make a 20" crb.
The Mytee OPM can't be beat for performance but is guaranteed to damage grout using their 1.5 hp machine with grout brush attachment. Ask me how i know... not cool.
I would definitely be willing to try the groovy grout. Especially, if it's high rpm. Besides, it's compact, light weight and will fit perfectly with the rest of my grout tools hanging in the rafters of the van.
I would order the groovy grout tool today but I need to order a replacement Cat Pump now! Also, the Mercedes dealer sent me a quote on Friday to repair my Sprinter van. The quote was 5k to get it running or $12k to pimp it out. lol.. So, I'm arranging for a tow truck to bring it back to the yard so i can fix it myself for under 500 bucks.
Also, I'm knee deep in tax prep so all discretionary spending is currently on hold.