Thinking Mg problem..

Hi All,

My plants are starting to show signs like this:

https://www.sensigarden.com/wp-content/uploads/2017/05/mag-deficiency-cannabis.jpg

Everywhere I look it says sign of Mg deficiency and I am looking for some options.

I am using a new soil recipe, basically subcool's but a local hydro shop has a kit with #4 sunshine mix, worm castings, and a mix with kelp, bonemeal, lime, etc etc. I transplanted about a week ago and am seeing the above symptoms starting to show.

Thing is.. I know the soil has Mg but not exactly how much. After cooking for 2 months the soil pH still tested around 7.4. I used pH 6.4 water when transplanting. My guess is this high soil pH is locking it out, but was wondering if any of you guru's out there may have a suggestion.

I know how to bring my soil pH up.. but cant find a lot about bringing it down. Maybe flush with low pH water until runoff is where it should be? Any help is greatly appreciated!

Thank you!

a pic would help but anyway, not really sure what all that stuff in the soil mix translates to property wise, maybe the soil is too hot with stuff, how old are your plants?
not sure on the soil ph, if thats too high or not, have to admit ive never ph tested my soil

Pics