What is a good wick for pro-mix in panda bags?

I am trying to find a good material to use for a wick - I have plastic panda bags filled with pro-mix. I tried using some nylon rope, but it does not seem like it is working. What is the trick, or what is a good material / source of wicks for a wicking hydro system?

Does the pro mix not wick up the moisture on its own? Assuming it doesn't, I can think of a few things.

First I'd try for the wick-mat the sell for use in ebb-flow tables and the like, and cut it up.
Some stores such as craft stores sell lamp wick by the roll
Perhaps thick "shop towel" type paper towels would work.

Go for natural fibers such as cotton when you want wicking, nylon and synthetics often don't soak in n the water as well.

But first, I'd try it as is- have you done that? Have you tried putting more holes in the bags, they seem to just have a few. Tell us more about your hydro system so we can see what you need. . .

So I have a plastic tub with about 6" of water on the bottom. I built a platform right above the water and the bags sit on that (not actually touching the water). I tried running some nylon rope inside the bag, out through the bottom - most hole and in to the water. The rope feels pretty wet, but is not really working.

I switched out my wick on one of the bags (3 gallon bag) with a "100% cotton" strip of towel. It is about 1" wide, a foot long. There is about 6" inside the bag, 6 inches from the bag down in to the water. Still not really seeing any good wicking action....??