Great article in the first post of this thread! Thank you.
A strip of simple cotton flannel, like 1" wide, makes a wick that will move more water than cotton string. But you may not need that much water.
When I have a potting mix that needs better aeration and faster drainage, I screen some clean, OK-smelling medium pine bark mulch through a 1/2" screen. Use the bits that DON'T pass through easily to really open up the soil in a big pot.
If you remove what passes through a 1/4" screen - rub hard - what's left may still be coarse enough to lighten potting mix for small pots. I even use it to lighten seed-starting mix in 72-cell trays.
That also makes any potting mix much cheaper, since 2 cubic feet of really high-quality mulch can be bought for $7-8. And the fines are great for lightening outdoor soil.
