over watered?

This is my first grow I was growing in coco coir with added nutes I think the nutes were a bit strong because as my seedlings are getting bigger the leaves are just dying off it, some of them are over watered this happened because I dont spend much time home and I was worried they would dry out, any advice to help fix over watering also can overwatering cause yellowing in the leaves and can it cause spiked leaves to fall off leaving the water leaves untouched any helpwould be good cheers also how can I add pics?

You fix over watering by watering less.

If you are away from home a lot try setting up some sort of drip feed system. Other than that as smokinrav said, lol!