I have had the same yellowing on my SeedStockers photoperiod Wedding cake and GG#4 growing in coco/perlite. After careful review and asking several experienced growers we came to the conclusion I was starving my plants. Upped the feed from 1.6 ec to 2.4 ec and they slowly all turned green again. Now back down to 2.0 ec and all is good. I am using Green Planet Dual Fuel nutes.wedding cake photoperiods are on day 30ish in 1.6 litre pots lights on pretty much 24/7 its a 75w Samsung strip on 50% hanging around 16-18 inches medium is plagron coco 30 % perlite with some clay balls on top 9 pots in total using the full shogun fertilisers line watered every 2nd day
Feed in today 2000ml at 22c
E.c 1.4
Ph 5.7
Runoff 1000ml
E.c 0.4
Ph .6.4
Temps 15-20c
Humidity 50-80%
I'm seeing some yellowing and im not sure if it's from a lack of mag or the ph is drifting up for some reason iv given them a 1.5ml per litre boost of cal mag today to maybe help but I'd like a second opinion from someone
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We concluded my ph and ec runoff were stable with good RH and Temps. I had been adding xtra cal/mag every second feed so stronger nutes was the answer for me anyway.