When you build a false bottom, the water level can't reach above that false bottom height. If your soil is getting wet by water, then either the false bottom is not high enough or the screen layer is letting soil fall through.

If problem is that the water level is above the false bottom; need either raise false bottom height or lower the water level.

If false bottom is below the soil level, then the screen has allowed shredded coco to fall through it. To correct that, you can remove all the coco and add a layer of polyester pad material (from aquarium shops or sewing store) above the screen, then replace the substrate .

Hope this helps, a picture of your set-up would provide more information to understand issue at hand. Good luck !