any idea? w/pics

Hi everyone-

Strain- Cheese
ph- 5.6
hydro- waterfarm
Light- 400mh
hours 24/7
watering- 2 times a day for 30mins
growing in- rockwool + clay peletts
location- 2.6 x 2.6 x 5.5 grow tent
nuts- Dutchmasters - part a&b gold - full strengh
temp-80-86F
water- bottled water.

So this is happening to my older leaves- not the oldest- but somewhere inbetween, the tip start burning and then the leaf starts getting lighter till it just burns off- it is growing new leaves on the top- but i'm just wondering what can be causing this.
Any idea on what this might be??
I have 3 plants int different water farms- and its happening to all of them.

Nute burn bro...

That is, at least primarily, Potassium def.

so to much nuts? hmmm

yeah i'd say nute burn (too high ppm in your nute solution). im strictly a soil grower so i cant say for sure in your case but i would try cutting your solution in half....ive never been able to use full strength without burning the plants...for that reason i quit going by what the label says to use a long time ago.