Flowering Stage 4th week in need of help

So I have a drain n fill set up with 175watt hps set up. I have recently switched out the res and started using a different chemical solution. I switched to Advanced Nutrients Jungle. The ph is around 6.8. The issue is that the leaves are starting to develop brown spots, tips are curling down, edges on some are also curling down into themselves. I was watering 4 times during lights on and switched it to 2 times during lights on. This helped the brown spots out a lot but the browning of the tips and curling did not change. I even added an additional gallon of distilled water to the res to lighten the strength of nutrients. Should I try to flush for a day? Should I water more? Should I dropp it down to feed only 1 time? Im at a loss. The plant looks good otherwise. I do know that during the lights out cycle sometimes it gets chilly (64degrees). Would this cause it? I need advice from fellow members cause im lost. I will take pics when lights come on if it helps.

The only thing that jumps out at me is your PH is too high. You want it around 5.8, not 6.8 and that can cause deficiencies of things that only get absorbed below 5.8.

Sorry I meant 5.8 for the ph. Also here are a few pics. It is hard to really get a clear iamage of what is going on but you can see the tip curling and the browning. Should I clean out the res and just flush with water for a day or 2 watering 4 times during light cycle? I always thought that curling under meant overwatering but I do not really know.

wow im surprised you picked up on that. You can barely notice.

yeah its hard to see in the pics but when you look at the overall its noticable.

Looks like nute burn, tips look burnt