Hello and welcome to the forum. Please discontinue the soaking, it may be part of the problem and will lead to other problems. I suspect that you are experiencing a problem with Fungus Gnats. The adults are winged but the juveniles are worm like and live in the soil. Have you noticed small flying insects?
These pests live in damp, organically based soils and feed on the roots of your plants. Try Google for some images to confirm and then you can search the forum, there have been previous discussions on this topic. If I am incorrect perhaps you can provide some more details.