it's not light burn, no worries, but moving light higher will reduce demand for nutrients on plant, so kinda helps as long as it doesn't cause stretch.
now, coco *can* leach your Ca++ and Mg++ cations out of your ferts, but this would also dump out K+. if it isn't a reputable brand, this isn't likely and i don't see a K-tox.. possibly the burned tip? K-tox can present symptoms of Ca and Mg deficiency too...
OR, there's an imbalance in feed / lack of something etc. You'll need to consider what you've been feeding your plant. a nutrient calculator is linke (2 of them) in my profile page. check it out. Also, watch dr. bugbee's video on maximizing yields. great info on nutes.
if irrigating properly, you can feed every single time you water and you should. ~10-20% runoff is key for this not to cause issues. Not too large of a pot relative to plant is also a big factor for that to remain true too. Don't quit treat it like soil.. top 1" should not dry, but maybe it could start to turn a lighter color and that's good eough. I would water couple times a day in coco, if you have the time. Fresh water brings fresh nutes and O2 to roots. Unlike soil, you cannot overwater due to lack of water retention.
Occasionally you may need a water-only irrigation, but shouldn't happne more than every 4-6 week if at all.
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