So it looks like damage has stopped for now and all I've been seeing is what's already been done. Decided not to flush, just lower the amount of nutes and wait for 1 more week to see in what way plant's condition will change. One of two plants looking decent even with all the yellow\brown spotted leaves, second one looks a bit less good, but still buds keep forming and getting bigger.
Ok so it is actually kinda difficult (NOT IMPOSSIBLE) to give them too much Ca or Mg. Magnesium deficiency CAN take up to 4 weeks before you even see the first signs. When you give the plants more, the damage will slow or stop almost immediately HOWEVER, if they were already deficient and you give them, for example, 1 gram of magnesium sulfate per gallon and they eat it and the problem is solved ,right? Except that when already deficient, they eat what you give them to recover but then they go deficient because they already ate the food and no more is left and then in 4 weeks you will start seeing yellow tips again. ANY nutrient, pH, or environmetal imbalances WILL slow the growth rate of flowers. Too much magnesium will resemble excess nitrogen without the burnt tips. Also, the ability to absorb Ca and Mg drastically decreases as the pH gets lower than 6. Oh and 1 morething that you might find useful, plants get up to 80% OF THEIR MASS FROM CO2. So enriching your grow with 900-1400 ppm CO2 will greatly increase your yield. Ify ou cant acquire a CO2 system just yet, then there are 2 things you can do that make a huge difference. Add carbonated water (pure carbonated/sparkling water from grocery store, just make sure the only ingredients are water and carbon dioxide) add the CO2 water to your nutes (it will lower your pH, btw) and put some in a spray bottle and mist them withCO2 water. I even do this in flower but only when the lights are on and with proper air circulation to prevent mold. Different strains require different things. My white widow supreme, for example, eats 2 grams of magnesium sulfate per gallon while my sour blueberry didnt show the deficiency at all. If she wants it, give it to her. Just make sure that the symptoms you are seeing are not caused by a pH imbalance or a different nutrient being too high or low