On Monday, March 11, 2019 at 10:57:31 PM UTC-4, condo owner wrote:
I have 120 "Multy" "Envirotiles" (made from recycled rubber tires) on my outdoor concrete patio slab.

Over the years, dirt, debris, muck, leaves, etc have accumulated under the tiles.

I'm going to take up the tiles, power-wash the concrete slab, clean the tiles and lay the tiles back down.

What is the best way to clean the tiles?
What detergent should I use?
What strength should the solution be (i.e., x part detergent to x parts of water)?

Power wash the tiles too. You can use any of the cleaning products for power washing, but I would just use water. Don't use too much pressure on the tiles.