Yellowing Leaves.. N Def?

[ChunkySkunky]

OK Thanks,

I thinned out below the canopy gradually over the first 2 - 3 weeks after flip, I took away all the sucker shoots, but I didn't want to take the fan leaves away as they were still getting some light. I am losing quite a few leaves from below the canopy on a daily basis, which I expected due to the canopy filling out. These are some of the leaves that are falling off from lower down.

I've emptied the res this morning and filled it with pH adjusted tap water, I'll leave it flushing all day.

I've moved the lights up to 24" away and made up some new nutes to add later. I use a bucket with 10L of water in.

Water EC is 0.5
3ml calmag - 0.7EC
7.5ml A + 7.5 ml B - 1.1EC
3.5ml PK 13/14 - 1.3EC

I'll add more water to that once it's in the res to take it down to 1.0EC and set the pH, sound good?

 

[ken dog]

It's worth a shot. ..hope it helps.

 

[ChunkySkunky]

well, it's been 4 days of low lighting and low feed, and things have got worse :( Still more leaves going yellow.

I read through this thread again yesterday and noticed I had written "everything was fine during veg", so I sat and thought about what I had changed after flipping (apart from going to 12/12), and then it hit me!

I bought a damn pH meter. Before that I was using the drops that came with the NFT tank. The canna nutes turns the solution red, and I thought that was making the pH drops read incorrectly (even though my plants were growing fine) So when I used the pH meter and it gave a different pH reading to the drops I thought I was right about the drops being inaccurate.

When the drops were telling me pH was about 6, the pH meter was reading 7.8, so I was adjusting it down to 5.6 using the meter, when in reality it could have been as low as 4.

The instructions that came with the pH meter said it was pre-calibrated and shouldn't need calibrating for 3 months, THEY LIED !!

Mystery solved, I really could f*cking kick myself, I am so so so pissed right now.

Hopefully I haven't completely fucked the whole harvest up, they still smell good at least :)

Thanks again to everyone who offered their help.

 

[hermit186]

I use drops to watch my meter I have used them for so long it get easy.