I don’t believe that, first time hearing. Please share the source
This is from Canna Gardening, and I think covers what I was referencing.
"The proportions (ratio) of the various nutrient elements are more important for recirculating systems then with any other system. This is because the plant directly influences the composition of the nutrient. Not all nutrients are absorbed with equal ease by the plant.
Potassium (K), for example, is absorbed much more easily than Calcium. In a recirculating nutrient solution, the potassium concentration will drop much faster while calcium might accumulate. Another important aspect of the nutrient is the type of nitrogen. If nitrogen is offered in the form of nitrate, the absorption of potassium and calcium will be stimulated while at the same time the
pH in the nutrient solution rises; if nitrogen is offered chiefly in the form of ammonium, the result will be the opposite."
here is the whole article linked for reference
There are a few things you have to take into account when you're growing on a
www.cannagardening.com
Based on the info here I would also agree with DaFreak that the OP is using far too much CalMag based on his feeding ratio. The high CalMag is likely causing other nutrients to be locked out, and then causing further imbalance in the nutrient solution. Remember that PPM is just an overall valuation of dissolved solids, so even at a low PPM there could still be a toxic level of one or even several nutrients.
Based on this additional information I feel pretty confident in my original diagnosis and suggested treatment.
Good luck!