Deficiency problems

[Spirit Cloud Star Chaser]

Hi Roll it up crew,
I've got a bit of a problem. My leaves at the top of the plant are yellowing in the veins and eventually turning brown and dying. I tried fixing it by upping the base nutrients and adding cal-max and that hasn't seemed to of fixed it. I'm growing in rec coco and currently in 5th week of flower. The coco (nutriefield) was a premium buffered blend (I did not buffer the coco).

Nutrients: Advanced nutrients sensi bloom coco, Monsta bud and Cal-max (calcium Magnesium)
EC 1.1
PH 5.8-6.4
I have had problems with rising PH, I've had to use PH down every night as it rises to 7.3. I'm watering 2 hours after lights on and 2 1/2 before lights out. If there's any other info needed let me know.

 

[boilingoil]

I'm growing in rec coco and currently in 5th week of flower.

does this mean recycled coir?

 

[Spirit Cloud Star Chaser]

does this mean recycled coir?

Yeah man recycled coco. I've done recycled coco before with no problems.

 

[boilingoil]

Yeah man recycled coco. I've done recycled coco before with no problems.

OK, just trying to clarify. normally fast pH rise is a indicator of the plant being hungry.

 

[hotrodharley]

What kind of light and how high is it over the tops?

 

[Spirit Cloud Star Chaser]

I've got a 1000 watt over 4 of them with a cool tube and that's about 1ft above them and a 600 watt above 2 of them without a cool tube and thats about 1 1/2ft above them. Ive got a 100ltr reservoir feeding them all.

 

[Spirit Cloud Star Chaser]

Ok so I just got my PH pen tested and it was way out. It was showing a ph of 7.3 when in fact it was 5.8 so I have been dropping it 1.5 everyday bringing it to a ph of 4.3, that sucks big time. If anyone knows the deficiency please let me know. I was thinking calcium. I will do a flush and start again.

 

[polishpollack]

I'm thinking... low pH is your problem.

 

[70's natureboy]

PH pen strikes again.