Should I use cal-mag?

sorry brain fart-- "In the case of Mg related symptoms..." They are not visible until 30+ days after inception of the problem inside the plant. If there is a deficiency occuring, it will take 30+ days before you see interveinal chlorosis with spots on leaves caused by the Mg deficiency. Not everything happens overnight and caused by the most recent event. Take notes. Be smart.

Unless the soil has all the calcium it needs, and can last until the end... you need to supplement Ca and Mg.. they are 2 different nutrients. That's a pro and con of soil wrapped in one... it's nice that your soil provides some, but you need to learn the balance of slowly supplementing what the soil doesn't provide over time. Taking notes helps greatly. In the case of Mg related symptoms (again, stop thinking of Ca and Mg as a combination.. they are not any more than the overall combination of NPKCaMgS - they are all needed at all times even if something may be needed less or more in flower -- most of that anecdotal stuff has not held up under experimentation, though) led or hid, doesn't matter. Coco or not doesnt matter -- if it does you got a shit-ass batch of coco that was not properly buffered and that is a fault of the manufacturer. Misattributing causality is rampant in the community. You can make 'super soils' that require little to now supplementation throughout entirety of grow. it takes some time to refine but it is definitely possible. You put in a lot of work refining it, but requires little work after that point. Just water and walk away.. maybe some sort of top dress at various points but that can be avoided too. i'm a big fan of soilless... 100% control over the diet of the plant.. knw what it was fed and makes for easy diagnosis and adjustment of formula... hit the ground running with great results from first grow by comparison. Each has pros and cons.. depends on personality... no reason for feelings of superiority or insecurity you often see out there about soilless/hydro vs soil.

Yes, I follow recommended dose on my bottle. Most of the times it is actually too little so around the 2nd - 3rd week of flower I up the dose slightly. It’s actually amazing how much they consume so it’s a must have in my opinion. Hope this helps.