Help me diagnosis a possible issue with these leaves

Plants 4 weeks old today (autoflower)
Coco coir / perlite (70/30)
Watering (RO water) every other day w/ Mega Crop dry nutes (1/2 teaspoon) 1.2 EC

Mars hydro TSL 1000 at 25% intensity about 2 feet above canopy

I’m thinking that I’m over watering a bit but I can’t put my finger on that discoloration I’m seeing in the leaf. Perhaps magnesium issue?

Thanks for any advice!

Are you supplementing cal/mag with the RO water?

I don’t think your over watering. I grow in coco/perlite and have a recirculating system that runs 4 times a day for 15 minutes. Check your ph, but if using ro water it’s probably ok. Use cal mag if not already, ro water has none obviously. I don’t use dry amendments so can’t help much there, but if using GH or something similar it’s near impossible to water coco/perlite too much.

HydoDan said:

Are you supplementing cal/mag with the RO water?

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Thanks for the question. No I’m not. The megacrop I’m using is suppose to be a “all in one” supply. However, I’m seeing a ton of mixed reviews on it so I’m not confident in that. Does the leaf look as if it could be a cal/mag issue? Thanks again

Hook Daddy said:

I don’t think your over watering. I grow in coco/perlite and have a recirculating system that runs 4 times a day for 15 minutes. Check your ph, but if using ro water it’s probably ok. Use cal mag if not already, ro water has none obviously. I don’t use dry amendments so can’t help much there, but if using GH or something similar it’s near impossible to water coco/perlite too much.

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Thank you for your reply and for that information, I really appreciate it. Now, I’m wondering if I’m watering too little then lol. I think I’ll go ahead and try adding cal/mag see if that does the trick. Are you feeding every watering?

5.5 to 6.5 run off ~ideal, what is yours? Also ec /ppm of runoff.

Thank for you the question.

6.3 Ph and 900 ppm.

BUT that’s because these last 3 waterings I’ve given them straight Ph water with cal/mag because the run off ppm before was around 1600-1800. So I think my issue was perhaps nitrogen tox and cal/mag deficiency. I could be totally wrong but that’s what my research is telling me. What are your thoughts?
Thanks again!

Sounds really high for r/o. Ph okay ppm way to high.

I like 700ppm (always, start to finish), with r/o and I’m even at that using 300 ppm tap now. 6 ph but mine usually rises so I start 5.6 or 5.8 and you get some movement in ph which is according to some good.

just my opinion.

For my meters 1600ppm would be Around 2.0 ( possible a bit higher), ec. But apparently there are different ppm scales which is why I think ec is preferred. I believe 1.3 ec is ideal when everything else is dialed in.

could be wrong about everything but I don’t think so

Thank you I appreciate that. This is solid advice. I’ll work on getting the ppm down and give less nutes when I do feed again