Yellowing on leaf tips

That looks like nitrogen burn to me. I’m not sure what you’re feeding the ladies but seems as though you fed them too much nitrogen and with the addition of cal mag that will make the nitrogen levels of the plants increase. Try flushing for a week Or so with Water. The discolouring and ‘clawing’ of the leaves probably won’t disappear but watch out for the rest of the plant. After say 10-14 days flush start to feed again gently, go with 1/3 to 1/2 of what you was feeding and gently increase. Hope this helps. Less is definitely more!

what gmslave said with maybe the exception that EC 2.0 for veg might be much too high if your light isn't strong enough.. (and with a strong light over 850PPFD it's best to add co2).. Most my grows under a COB don't need a higher EC than 1.4 during veg.. if you're in an DWC, just measure the EC of what you put in, and then again the next day. If the EC goes up you feed too much (which could cause nutrient burn and such tips), or there's a lot of evaporation happening.. if the EC stays the same, you're good, and if the EC goes down, then you should bring it up..

It is also essential to keep water cool with dwc. Freezer packs if you don't have a chiller on hand

Are they just starting to bud? If so then you have things wrong. When you first turn lights down and the stretch begins is when you increase your veg nutes until you see nice button size nugs starting. Ph until that time should be 5.8 and maybe 1000 ppm 2.0 ec. After button nuggies appear then drain your water clean everything and relill with half veg nutes and half bloom for the next few days ph 6.0 0r 6.2 max. Ppm now should be lower than veg, not higher. 600 1.2 ec to start 800 1.6 ec max if your plants need that high. Some do some don't. Hope this helps