Step 2: Phase 1: Prepare the Astroturf!!
Let me also stress that before you start gluing and cementing everything together, please do a dry run and make sure everything fits correctly and is the right size/threading/etc, otherwise you'll end up wasting parts.
1. First off, you should start by taking the tape off of the Astroturf sample.
Remove the sticker on the back that marks its model number and information. Otherwise this will become wet and get all gooey, and you don't want that seeping into your rope. It should be fairly easy to remove with your fingernails. If that fails, try bending the astroturf to break the glues grip, or perhaps using the steam function off of a laundry iron.
2. Next, fold the Astroturf piece like a taco (or 'Hot Dog Style" ) and try slipping it into the PVC Tee. It should preferably fit fairly snugly, not so tight that you can't push a sharpie through from one of the other, but not so loose as to not provide contact with the full circumference of the rope. Remember that the astroturf will mat down once it becomes saturated, so you can make it moderately tight. I recommend building the scrubber without cutting the astroturf first and testing it before you decide to increase the interior diameter. Also, you can now call this "The 'Turf Tube"
3. If you must cut the astroturf down to size, do so in small increments down the entire length of one side, so as not to over do it. Remember, measure twice, cut once.
4. Once you are fully satisfied with the interior diameter the rope will pass through, cut two small triangles on opposite sides of the 'turf square. Cut them right in the middle if you can. See the photo for details. These triangles open up a hole once the 'turf is in the PVC tee so that the water will come through more quickly, increasing the amount of water that is contacting the rope and reducing the amount just spilling out the sides