Yellow at 3 weeks in bloom

[Electrified]

Not sure why but my plants keep turning yellow at around 3 weeks into flower. I’m using double ended hps bulbs air conditioning and co2, I’ve tried switching nutrients, I’ve trying adjusting the ph up and down, temps I don’t know what going on.
Strain purple candy
temps 82’
co2 1000
current nutrient green planet 3 part

any help would be appreciated!!

[DoctorJohnson]

It's hard to evaluate leaves that are shot under unnatural lighting--the yellow cast in this case makes it hard to evaluate the yellowness.
I'll guess magnesium deficiency, though. http://www.growweedeasy.com/magnesiu...iency-cannabis Maybe a little Ca too? (Brown spots) If so, a slug of Cal/Mag ought to fix you up (and you should probably keep using it till harvest). Do you have really soft water or are you using RO?

Pretty flowers!

<edit>One more thought... does your nutrient regimen really cut back on nute levels when you go into flower? I suspect maybe (just maybe) some might cut back a little too much?

[Canuck147]

I'm agreeing with the Doctor here - should also make them greener.

[Jr83]

Have u tried lowering ur nutrient levels and flushing out excess salt build up more often?

[DoctorJohnson]

If you're fertilizing right, "flushing out excess salt build up" shouldn't be necessary.

[Electrified]

I was already using a bit of calmag but after checking the amounts on the nutrient bottles I decided to up the dosage a bit. I have been giving them fresh water every second time so there shouldn’t be much for salt buildup. I have been using recycled dehu water and tap water together, ppm is usually around 100 when I start mixing. I have never used the double ended bulbs either, how far from the canopy should they be?

[DoctorJohnson]

100 PPM isn't a lot of mineral content. Assuming the the dehu H20 is 0 PPM, maybe skip using that and just use tap to get a little more mineral content? (And/or dose with CalMag. That's what I do. With our super soft water (20 PPM), if I don't add Ca and Mg regularly to my coco, the leaves start looking bad fast.

Dunno 'bout DE bulbs. Wish I did!

[Electrified]

I think this all stems from a high heat low humidity issue, I put my thermometer at canopy height and found heat at 35 and humidity as low as 25!

[DoctorJohnson]

That's not ideal, but it's not going to cause those color symptoms--more like taco'ed, even crispy leaves.

https://www.growweedeasy.com/wp-content/uploads/2010/10/leaf-edges-tipped-up-from-heat.jpg

https://www.growweedeasy.com/heat-light-stress

[Harry]

First couple weeks of flower is the transitioning stage. You need to mix your bloom and grow nutes together for about 2 weeks. The plant still needs nitrogen to make it through the stretch and the bloom will be there for your budgets to form

[PaganRich]

I have been having the same problems myself...half my tent is great, other half yellowing. I use organic compost tea and very happy with my nutes spectrum. Added extra fans for greater airflow, raised my lights slightly to remove potential light stress. Still getting this issue which is fairly recent and the only thing I can think it could be is temperature fluxuations between day and nght temps. I use a 6" fan to bring air into a 120x240 tent and this is an increase on the 5"`s I used to use. My thoughts are , cold air comes in, hits the girls near input (3-4ft)at a temp of around 8-10 celius during night then temp rise during day. Weirdly, when moved and after some time, some green does return to the leaves. Not sure this is what`s happening with you but looks similar. Anyway, hope you get a solution

[Electrified]

They are still a bit hurting but I added another fan and raised my lights too, I hope it helps.

[PaganRich]

Hope that sorts the probs out. Be interesting to see the outcome. I found potency to be the same if not a bit stronger, funnily enough. As a thought, another thing I do is to aim the air intake near an oscillating fan which is near a dehumidifier in the tent which has it`s hot air exhaust panel aimed in the same direction. Now I`ve only just started this so I don`t know the outcome however when lights go out and heat drops, I turn the dehumidifier on. My thinking is the venting hot air from it will rise and meet the intake fan`s descending cold air and mix, making it more neutral and less harsh before moving around the girls. I really recommend also hanging strips of paper around to check air flows for any gaps missed that may become stagnant.

[PaganRich]

Electrified Couple of pics to show idea of fan/ dehumidifier from above