Cal - Mag Deficiency????

I grow in DWC and keep the PH at 6.2 throughout the entire grow. You will not experience deficiencies at this level as long as you provide what is needed. It is very tricky adding a single ingredient to your solution, easy way to over correct. I’d start with a new solution change that included what you thought was missing. Your plant looks very healthy, if it is a minor problem just wait until your next scheduled solution change, don’t panic! Hope this helps!

you want to mix everything al at once. when you add a gallon of something else itjust dilutes what is there. you want 100+ ppm of Ca. Your tap water may need more or less, but 100+ is a good starting spot. Mg is 50-75 ppm.. again, your tap water may have some say in this matter. I find i need more Mg in vege than flower. overall concentration should be around 1.3-1.5EC and you can observe and adjust from there. If you don't want a full water change, guesstimate volume of what is there... Add a specific volume, like 1/2 gallon or 1/gallon, whatever is convenient. Add the incremental difference of the rest of your nutes for that small volume, but also add enough calmag that you needed in the entire volume for what remains + incremental volume. This would be like adding calmag to start. fertilizer should be cheap. just drain it and re-do your mix including the cal mag + other fertilizers for refill, in my opinion.. throwing out a few gallons to be a bit more precise is an easy choice. soilless / hydro is all providing all that the plant needs in the right ratios and concentrations available at all times.. any time the roots draw in water. You may need slight changs at different times and for different strains I would disagree with pH suggestion. Going that low will impact availability of Ca -- which if that was low to start, would obviously exacerbate the problem. Since you are in hydro, start tracking ppm of each primary/secondary nute etc. N-P-K-Ca-Mg-S. there are apps.. there are online calculators etc. If you are already giving 100-120ppm of Ca, you probably don't need more, for example. If it's significantly lower than that, adding more is probably wise... Knowing and trackign this stuff is not always going to give a clear answer, but it is an incredibly useful tool to have in the bag. It does help eliminate choices when assessing leaf symptoms. If systematic, you'll quickly refine the formula to avoid nearly all problems in future.. at least anything related to nutes.

Your pH is a little bit high for DWC, I would try to get it down in the 5.2-5.5 range to see if that helps before adjusting your nutes. Different things uptake better at different pH ranges.