What's with the yellow veins?

Looking for the cause of this yellowing of veins on upper leaves. Three weeks since potting clones and seeing similar symptoms on most of the plants. Using FFOF with Cali hot soil in the bottom third of 5 gal fabric pots. LED 400w fixture at 50% (recently lowered to 25% after seeing some tacoing) with 24" clearance on 18/6 schedule. Temps 68-70 night 72-76 day. RH 60%-70% and VPD .6 to .9 most of the time. No nutes so far. soil ph is 6.2 and using rain water with ph 7.1 when moisture meter approaches DRY about 4" down. I haven't found pics that really match what I'm seeing and would appreciate advice from anyone familiar with this.

Looks like pics of sulfur deficiency. Epsom salts may fix.

thanks simpleaf. would you spray or add when watering?

I'm not a fan of foliar feeding, but have occasionally used it. Good luck.

Could also be iron deficiency, or iron being locked out by high soil pH. Conveniently, elemental sulfur can also be used to lower the soil pH... however it looks you're gonna want something fast-acting, so foliar sprays would be my first course of action (either epsom salt and/or some micronutrient product like TM-7)

K Mag or Gypsum

Try to get your temps up in there. 72-76 is quite low for lights on

I'd be suspicious of the accuracy of the PH tests given by the OP.
It's possible his rain water is 7.1 as it happens in certain areas, but it is rare. Rainwater is usually below 6.
This would make me wonder if the soil PH is really 6.2.

Kushash said:

I'd be suspicious of the accuracy of the PH tests given by the OP.
It's possible his rain water is 7.1 as it happens in certain areas, but it is rare. Rainwater is usually below 6.
This would make me wonder if the soil PH is really 6.2.

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Used a pool test kit and a digital probe to verify the water ph. Tap here is lower, but still close to 7. Would you switch to that? My rain water is collected from a new concrete tile roof so maybe that's affecting it.

Boatguy said:

Try to get your temps up in there. 72-76 is quite low for lights on

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thanks boatguy. that's an easy one to fix

flowrrpowrr said:

Used a pool test kit and a digital probe to verify the water ph. Tap here is lower, but still close to 7. Would you switch to that? My rain water is collected from a new concrete tile roof so maybe that's affecting it.

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Thanks Kushash. I didn't question the soil ph result because I've read that FFOF is supposed to be 6.2-6.4, but I will retest. My wife's miracle grow ps also tested at about 6.2 with my vivosun ph probe

flowrrpowrr said:

Used a pool test kit and a digital probe to verify the water ph. Tap here is lower, but still close to 7. Would you switch to that? My rain water is collected from a new concrete tile roof so maybe that's affecting it.

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I don't know anything about roofing tiles but maybe the calcium in the new tiles is affecting the PH. I would compare it to rainwater caught away from the roof.
Tap is used by many growers as is rainwater. If you have soft water with a low EC it should be OK. If you have hard water with calcium build up on nozzles it's sometimes better to lower the EC or ppms by mixing tap with RO.
This link will help.
PPM: What It Is and How To Track It | Grow Weed Easy

PH of your soil makes little difference, unless its extremely high or low. FFOF is buffered. What's important is the PH of the water with nutes that your adding. After adding calmag, wait 15 minutes, then add nutes, wait another 15 minutes, then PH the mixtue to 6.2 and water to runoff. The plant will immediately take in the nutes available at PH 6.2, then as the PH rises the plant will take in the nutes that are available at the higher ph level.

flowrrpowrr said:

Used a pool test kit and a digital probe to verify the water ph. Tap here is lower, but still close to 7. Would you switch to that? My rain water is collected from a new concrete tile roof so maybe that's affecting it.

Click to expand...

https://www.amazon.com/General-Hydroponics-Test-Indicator-8-Ounce/dp/B003Y3F34I/ref=sr_1_3?crid=4BHHH5VIYP8A&keywords=ph+test+fluid&qid=1674921757&sprefix=ph+test+fluid,aps,124&sr=8-3&th=1

not accurate to within .01, but more than sufficient for growing weed, and as long as you don't contaminate it, it's NEVER wrong...
no recalibration required.

If op is using one of those silly moisture /ph meters you stick in soil
Throw it away
I bet your runoff is much to low if you were adjusting ph in hot soil
Not really sure as my medium has no nutrients from square one
And my tap water is 8.2 and I don’t ph but nutrients do lower it
Edit @flowrrpowrr
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