Here's the way I see it. I don't know what the instructions are on the back of the container for calmag, but you want to follow those directions. It sounds like 3 tsps in just a few days is alot, maybe too much. I've never heard of plants suffering from too much of either cal or mg, but that doesn't mean it can't happen. Usually when you have lush green leaves with some tips turning yellow/brown, they have too much fert and you're getting fert burn. So the question is, what soil did you put them in, and have you given any other fert?
At this point I would leave them alone and see what happens. If the browning of the leaves worsens, then you have too much fert in the soil and I'd probably give a plain water flush, then let the soil dry out some. If you use a fert like ocean forest, it probably has quite a bit of fert in it, so since you've put them in large enough containers, what you can do is just leave them be until the start to show something other than green growth. Toward the end of flowering and their life cycle, usually about 4-5 weeks into flower, the leaves will start to turn yellow as the plant begins to die. Give nothing during this period except water, to flush out ferts from the plant and let it die. Then cut her down after about a week or so of this.
Do I have this right, that you've given nothing other than the cal mag? I think you've given too much actually, so I'd probably give a bit of a flush and then leave them be and see what happens. Meded saying "feed in two weeks" is not a bad suggestion but depending on what soil you're using, you need to be careful how much, if anything, you give at this stage as it looks like from the leaf tip burn, there's fert in that already. But that's just how things look in the photos and from what you've written. If you buy good potting soil, it can be difficult to screw up a grow (unless you really don't know what you're doing and never ask advice).
Oh shit, I just re-read your older post and saw you've used bat guano in the past. If this was retained by the roots and then put in good potting soil, this could create an over-fert condition. A flush is probably called for, about a gallon of water per pot, if the guano was retained. Or you could simply do nothing and just let it ride to see if it gets worse. If so, then flush. Also, it's a good idea to wear sunglasses when working with metal halide lighting because they put out hard UV rays which are bad for your eyes.
polishpollack Reviewed by polishpollack on . Ok, I expected problems! What is your experience level? (first timer, novice, experienced...) First time grower Your Equipment: .1) Type and wattage of lights. (MH, HPS, CFL's, tube fluorescents, LED's) Sunburst 250W with a 250 WMH .2) Distance from tops? roughly 2 feet .3) Reflector type? (cool tube set-up, bat wing, enclosed reflector, bare bulb...) enclosed reflector .4) Is there a consistent fresh air supply? yes .5) Do you have an exhaust fan and a circulation fan? I have a circulation fan and leave my Rating: 5