Sounds like you're drowning your baby, because it should be alot bigger than 5", at 1 month old. No biggie, alot of new guys do it when they first get started, because they can't resist giving them too much lovin'.lol Same thing with fert....if you're using good soil you will need little, if any, fert while they're in veg. I use Fox Farms Ocean Forest, go to 1 gallon pots after week 1, then veg til week 4 and end up with plants that average 16-18". Then I go to 3 gallon pots, let them adjust to the transplant for another week, then go to 12/12 and end up with plants that finish at about 30-36" tall. With that method, I don't use any fert while they are in veg, and never run into any deficiencies. I start feeding after a week of 12/12, as they are going through their stretching period.
Ooops, I got side-tracked and forgot about the overwatering,lol.....The best method is to let your pots dry out almost completely between waterings, then water them heavily(until it just starts to trickle out the bottom of your pots), and repeat as necessary.
Also, it is a really good idea to get used to picking up your pots and feeling their weight, before and after watering, and eventually you'll know exactly when they need watered, by feeling how light they are.