leaves turing yellow / buring - need help ASAP

I am having an odd problem. I am growing 3 plants under one 1,000 bulb; 1 is Yum-Yum and the other 2 are Voodoo Everything was going well, until at about 45 days, I've noticed that leaves on Yum-Yum started to turn yellow. About 5 days later on one of the Voodoo plants started to turn yellow and started to burn. Even the leaves that are about 1 FT away from the light started to burn. Now I am at 55 days any leaf that sees bulb light is pretty much burned.

What is going on? I have use this set up last year, at the same time of the year, and everything went flawless. There is not much heat under the lamp. Over-all temp in the room is about 65 to 68 F. Please help. I can not cut the plants yet, as they are not done yet. Trichomes are just stated to get milky. So I figure I need at least 2 more weeks, just not sure if the plants will make it.

Here is are some pictures.

Just let her go the two weeks then harvest.

I am afraid that they won't make it.........They look scarier and scarier every day.

Any ideal what could have caused this burning?

soil, hydro, are you flushing ?

Soil (FOXFARM).
Started to use water 5 days ago.

you got some measurements for your ec and ph, if your flushing anyway, iwould personaly stick with that untill harvest, looks like you went a bit over the top on the nutes, are these clones of your plants from your previous grow ?

my PH is 7.5, which is could be a little high. i think ideal is 8+. am I correct?
i have been using water for the last 5 days and planning to continue to water until the end.

the most interesting part is that leaves that don't get much light, are nice and green. only leaves that are getting light are burning.
and plants are not that close to the light, so i can not image that it would be heat related issue, but i could be wrong. still learning.

ph your water to 6.5 and just give them that, the damge is done i think on this one, although they look like reasonable sized buds considering your ph. 8+ on your ph is waaaaay out. i cant really make it out from the pics, but do you still have a lot of white pistils, either way give them a good run through with ph adjusted water. .. peace

no dude ur ph needs to b more like 6.5 flush and make sure its phd water

OK. I think I've been measuring my PH wrong. I've been sticking meter in the ground and getting my readings from that. (i have a basic meter)


Right now I am giving just water, but I will change to PH6.5-Water

Thanks.

sorry forgot; I do not have many white pistils. only on the lower small buds and buds that did not get a lot of light. Trichomes stated to get milky on the top buds about 5 days ago.

im guessing if your measuring the ph of the soil directly it would want to be more like 5.8 or 6.0. next time round buddy get yourself a ph pen, it will save you a lot of trouble and can be had for about £40. ive had mine for about 18 months. you can get a ph test kit for next to nothing if pennies are tight, just a pain in the ass i find compared to a pen. i tend to harvest mine just as i see amber, always down to personal preference

Thank you everyone for useful info. This is my 2nd time growing, so I am still at a learning curve.