I've been using the mosquito dunk bits in the broms but will try the coffee next, I have to have the dunks muled down from the US, I've never found them here. The type of mulch sold here, mainly at Home Depot, are some kind of wood chips. They are large enough that they could allow small pockets of water to form. I generally add a couple inches of peat moss every year to make up for the soil that has washed down and away, it's sort of a mulch but is small enough pieces that it doesn't trap much water.
