Ok. Plants are on day 27 of flowering, day 57 overall.
I water typically once a day sometimes every other it just depends on when the soil gets dry. Even when the soil isnt dry yet I pick up the pots and if they are light like an empty pot I water them. I was using MG blooom Booster its a 30-15-30. I diluted it to like 10% and used it every other watering until last week I was up to using it at 40% strength and every watering... I went up gradually every watering the last 27 days. I let tap water sit 24 hours before using. I am using a 600w HPS and 10 23W 2700k temp CFLs. I have an exhaust fan that vents to the roof and an intake fan that either brings it under the door of the room, or brings it in from an external source under my house. Any other questions fire away
Over watering mixed with possible nute burn. Unless your growing in like a 32 ounce cup you should not be watering every day.
What size container?
I use 1gallon grow bags and I water every 3-5 days. I suggest you get a cheap soil moisture meter and water when the needle says dry. No way it feels light when the soil isn't dry as you stated. I did not trust myself till I got a meter and trust me when they are dry they are really really light.
Next you should never feed every water. Feed once a week and ever other watering.
Do you ph your water before you give it to your plants. This i suggest you do as well. especially after you add nutes to your water. My nutes drop my water to as low as 5.2. That would lock out mad nutes in soil. So you need to be on top of that.
I suggest you flush when the soil gets dry if they can wait that long. Go get a moisture meter and flush 2 to 3 times the container size. The next watering feed them 1/4th strength nutes and than if they take that fine the next feeding you could try higher nutes or stay at that level for another feeding.
This is the best you can do for right now. I would also suggest you find nutes with a high p and k and a lower N. As you might have a deficiency well but I think nute burn and over watering are your most immediate issues and why your plants are dying.