Little bit of leaf damage. What is it?

What’s up fellas, noticed a little bit of yellowing on the edges of some fan leaves the last couple days. It’s not a yellowing i recall experiencing before. Not crispy just a little discolored. Only seeing it on a couple of plants in a batch of 15. Temps are a little higher then normal at about 80. Humidity is between 45-55. Putting an ac in today. Was planning to go into Flowering tomorrow so I want to fix this issue. The are getting advanced nutes coco a and b grow. What are your thoughts?

As always, any advice is much appreciated Thanks in advance

Looks good , flip when ready. Sometimes overthinking a random discolor can lead you doing things that might cause more issues.

Budzbuddha said:

Looks good , flip when ready. Sometimes overthinking a random discolor can lead you doing things that might cause more issues.

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Thanks man. Initially that’s what I was thinking. Maybe it’s nothing. But then it became more then one plant which is what concerned me. I am kind of leaning towards it being a magnesium deficiency. Looks like the early stage of the picture I attached on this post. I know a lot of people have had calcium or magnesium deficiencies with advanced nutrients ph perfect and ro water. And the company says not to add anything else to the feed schedule. I was having calcium def earlier in veg so I started using my ro with a little bit of tap water to bring the Ppm up to 125-150. And up until now that was doing the trick for me. So now I’m not sure what I should try. Maybe I just need to up the base nutrients a little bit. I’ve been feeding at half strength because the leaves are always perky so they didn’t seem to need anything more then that. Around 800ppm. What would you reccomend. I’m still going to make the switch to flower because I can’t let them get to tall on me but I do want to address the issue before it gets out of hand on me.