Light-green stripes in the middle of big leaves

Hey all, and thank you so much for all your answers 🙏 I am still unsure what is going on here. Thanks to @Ezzjaybruh and @Jays_Not_Here_Man I looked into magnesium deficiency and what I can see from other pictures on google, it looks very similar to mine. I deffiently think this is the or part of the problem. Thank you @GrowingGrannie for your answer, but fortunately I don't see anything wrong under the leaves (I have added a picture to my diary). I also want to thank @Creepy_Steve for the very detailed answer! I do however have some follow ups Let me start with a answer to your first question. My meter is in the PPM-500 scale (not ppm-700). So 500ppm = 1000 us/cm = 1.0 EC. I always use EC now to be sure everything is right, so the EC level in my diary is correct (about 1.4-1.6 EC, and tap water is 0.4 EC). About the PH level, I always lowering the PH level with a soloution of citric acid / water, added slowly to the mix until around PH 6.0. I added a mix of PH=6.0 and EC=1.5 to the plants yesterday and measured out the run-off today, 12 hours later, and the result was 1.0~EC and 7.0 PH. I don't understand why the PH has raised by 1 point? Is it normal? About the coco I will make more irrigation the next couple of days to be sure

Given specifics.. this is likely mag deficiency starting to show up. If not properly buffered - coco will leach mag and other nutrients from your feeds and they will not be absorbed by roots for your plant to use. This is why cal-mag is recommended with coco.

I don't think it has anything to do with nutes... check for little critters/eggs under the leaves... if you find any, get some Dr. Zymes Eliminator or some Spinosad... both are organic and both can be used straight through to harvest if needed... Good luck!

Hey Growmie, I think it’s easier than you think, I believe it to be the start of a magnesium deficiency. Yellow spots on the edges or between the veins of the plants older leaves, while the veins themselves remain dark green. The leaves may show spots of necrosis (brown spots), and the most affected ones will fold over themselves and die eventually. Increase whatever your using for Cal/Mag supplements and you’ll be fine 👊🇨🇦❤️

It looks like early interveinal chlorosis, but so many things can cause that. Ensure pH is 6 of anything you put in and maybe check runoff too. 700 tds, assuming hanna-scale(500 = 1.4EC), is in a safe range to start.. could need minor adjustments related to this. Another possibility is that coco batch may have needed another wash. the way the leaves are turned down... but if so, a few irrigations would right that ship in no time as it isn't killing the plant or anything -- not too severe. speaking of irrigation habits... first time in coco, so just to be sure -- feed every irrigation. Be religious with a 10% runoff (or more is okay, but can dial back to 10% to limit waste). This will mostly ensure the pH and EC(or ppm) of substrate is in a consistent range relative to what you feed. Better off with 1/3rd perlite with 2/3 coco. soil is better at 50/50. coco holds about 2/3rds the volume as typical soil does, you can see how it is proportional. anyway, promotes better root growth and helps impede compacting of substrate over time.. each irrigation "pounds" it down. This does increase irrigation frequency a bit, can mitigate that with a larger pot if you want to. becareful of ppms.. 1.3-1.5EC is more translateable. yours and my "TDS" pen, if i had one, can calculate the ppm differently. use "EC" to be safe. if your calculations come to 650-700 for that range, we are using the same scale. Depends on the brand of TDS meter. There is an online nutrient ppm calculator at manic botanix. it's worth it in soilless.. you will see upper and lower ranges of what works relative to your pH over time.. know when something is low or high with more confidence and certainty..