Expanded clay & fleece against dirty water from flower boxes
Against dirty water from flower boxes: with expanded clay and fleece.
Who does not know that? In the flower boxes, which have an overflow hole in the soil for excess water, runs out just in heavy rain, a dirty broth out.
On the other hand, there is a simple tip:
Fill the floor with expanded clay to about half the height. Of course, leave the overflow holes free.
Over it put a suitably cut situation fleece (there in the hardware store with garden accessories). Work as accurately as possible, so that no water can run alongside. Then fill in the potting soil and plant the flowers.
If it rains now, the dirty water is filtered, it comes out only clear water!
Try it, I've been doing this for years, because our neighbors directly below our balcony railing with the flower boxes have their terraces.