Leaves with yellow spots

I reckon it's calcium deficiency. You said you're adding CalMag already, but even so it's not uncommon to suffer from this when using RO water. You might have to double your CalMag feed - when it comes to RO water, I find that the recommended dosage of Cal-Mag is "prevention" rather than to actually fix a deficiency. If you're already using Cal-Mag at higher than the recommended dosage, then it may be being caused by your PH being too far out. Calcium and many other elements (e.g. Magnesium) are more easily taken up by the plant if the PH is at the higher end of the acceptable PH range. Try increasing PH to 6.2 in that case and see if that helps. Type "cannabis PH nutrient uptake chart" into Google if you want to see a chart showing the uptake PH ranges for each element. I haven't used Advanced Nutrients myself personally as they always seemed ridiculously overpriced to me for a clever name and a picture on the front of the bottle... plus I see people having far more problems with these than any of the other major "premium" nutrient brands on here! However, maybe someone who uses them regularly will have some brand-specific knowledge they can drop on you which might help. Good luck!