RQS Skunk XL on Coco under LED

There's always sunshine after the rain. Week 2 was a struggle, but during week 3 the girls recovered and grew quite a bit. They even start to smell a bit. After I found out the roots were completely underdeveloped in week 2 and also shocked the plants due to transplant, I switched to another fertigation strategy: wet/slightly dry instead of a high frequency fertigation strategy. A day or 5 later, the plants perked up. They were no longer drooping and I saw some fat, hairy, bright white roots growing at the top of the medium. The few roots I saw during fertigation, looked a lot better than when I was transplanting them a day or 10 ago. When they started growing again, a new problem became manifest. On some of the lower leaves, some chlorosis and brown spotting became visible. It looks like a Ca deficiency. I am growing on a well buffered and rinsed coco medium, 35% perlite added, but I didn’t bother using a CalMag supplement. I was under the impression it wasn’t necessary because of a statement on the website of GHE, but, as you can read in the comment section below, the symptoms of the plants show the need of a CalMag supplement. This brings another challenge. The EC of my tap water is quite high (0,5 mS/cm). If I dilute the GHE FloraTrio nutrients mix to 50% of the recommended dose, I already end up with an EC of 1,2 mS/cm. Hence, there’s not much room to add a CalMag supplement without burning the young plants. On day 20, I fertigated at EC 1,3 mS/cm. On day 22 I fertigated again and started using a nitrogen-based CalMag supplement. Diluting the GHE mix 50% and adding 50% of the recommended CalMag dose, resulted in a EC of 1,4 mS/cm. Today, day 24, I noticed the very first (and super small) signs of burned tips. And one of the younger leaves showed the typical too much nitrogen point curved down. Conclusion: an EC of 1,3 mS/cm is the maximum the plants can handle right now. Today I fertigated again, I used the GHE CalMag supplement instead (less nitrogen). Since the symptoms of the Ca deficiency were still spreading (tho, very, very slowly), I gave a bigger dose of CalMag, but therefor, I could only add 33% of the recommended dose of GHE FloraTrio. It resulted in my target EC of 1,3 mS/cm. I think I can start daily fertigation soon, maybe even tomorrow and see how the plants react on it. It will probably be a mix of 50% of the recommended dose of FloraTrio and 50% of the recommended dose of CalMag for now. The girls are now working on their sixth node: it’s time to top them. I will top when the symptoms of the (early stage) Ca deficiency stop spreading. That might already be tomorrow. The same goes for the light: it’s still around 40% power. I guestimate that’s around 300 PPFD in the center; last grow the plants had no problems with 50-60% power. However, since they were in stress, I waited to power up the lights. If everything turns out to be in check (finally), I will also power up the lights a day or 2 after I topped them (unless they are stunted again). Thanks for all the help and advices when the plants were stressed and stay safe!