By all means....start your CalMag asap. I start CalMag the first time I introduce nutes to my seedlings. You could raise their general number as well....but props for not pouring every thing you can get your hands on into your res and frying them. That's generally the biggest mistake folks make. :thumbsup:

Good luck.....sounds like you've really put some work into it.

PS....when your ppm drops like that (140-110) they're hungry!