Its getting better

Let me break it down alittle i have a 5x5 grow space with 6 plants in a deep water cultivation system with a 1000w hps blub in a super sun 1 hood with a peice of tempered glass that was about 3 1/2 ft away from to of plants now ive lowered it to 14 in it is air cooled by the a/c running straight from the vent into the hood and out the other side into the attic its about 89f with the light on and about 85 when the lights off the light is 18hr on 6hr off my Ph balance is between 5.5 & 6.0 im using a purebloom fert (2.5-2-5) i have a fan on 24hr my problem is that the leaves on the bottom are turning yellow from the outside of the leaf to the inside it was worse but is getting better these two pictures are from before i changed everything [attachment=o71988] [attachment=o71989] this is after [attachment=o71990] [attachment=o71991] any suggestions are helpful