Still wanting more I think. How high have you been? The Mg looks to be your real issue and it's kind low in your 5:1.5 so you may have to take it up with some epson salts to stop the Ca competing.
Other clues are them chucking out roots to find food, and the low light level plants being happy. I'm actually vegging some great looking plants on 10w per foot of cob and wish they would slow down a bit as I'm not ready for them. That power level would be crazy under hids. It's hard to believe without seeing it. I could want for nothing more.
I have some 5:2.5 and I'm using 1.5ml per liter. Mid bloom I have been sticking 1.5g of epsom in each 10L of water, which is like another 1ml per liter of that 2.5 so I'm really stacking it in. It's Mg I struggle with which seems to be pushed out by the K and if I push up the Ca also it hinders the Mg. Most bottles are between 2:1 and 3:1 and yours is 4:1 and I'm playing around the 1.5:1 mark.
Many people will have a knee jerk reaction based on the published ratio's from long ago. We don't believe in that in the UK. Things just need enough. Whatever that is. LED's are not going to comply with the old ideas as it's not a heat based light. Straight away we add calmag to anything. That ratio stuff says the K must come up, but that's just defeating the object of the exercise. They need Mag. Then perhaps N and P but we need a look at them with the Mg first. All added up... you can see why many people increase base by 40% as a blanket treatment. Or you could lower the illumination. You have seen you can walk but not quite run yet
Just noticed that 1% N in your calmag. I have 3% in both mine. For about 7L in a bucket I'm using 50ml of my base containing 2% then 10ml of my calmag with it's 3% so that's 15% more N from the calmag and my N-acid is offering up 10% more (which helps carry some unknown hard tap) So I have a 25% N increase and I have on occasion added some urea when using my flower up to week 4. My food just worked with HID's but did show Mg if the salts were a bit high.
All interesting stuff, and that may well explain it. However after feeding calmag at full strength for water and feedings there really wasn’t a change, The same issues still maintained and perhaps worsened. I understand they might need more Mag. I stopped using the calmag in the last week, convinced the light strength or spectrum strength was causing the issue and the plants actually seemed to do better not using it.
I’m just having a hard time seeing how 300w of LED is creating an issue that 250-300ppm of cal/mag won’t even show an improvement. I think moving the lights up until I get proper growth surpassing the 20w growth and then coming back to the calmag might be ideal.
Likely a full strength dose of nutes could help.