First, why would he flush his soil for a cal/mag issue? Secondly, flushing soil with PH issues is a waste of time because: A. by the time you flush, the damage is already done. B. If your using organic soil, you end up flushing out all the nutrients. And lastly, its actually almost impossible to get accurate ph readings from soil, its not like testing coco because of the way ( CEC ) soil retains nutrients. When you see a ph issue in flower, you know the ph is low because of the H+ ions produced by the plant accumulatein the soil, making it more acid. this is why we put lime in our soil mix, to buffer this.
And if your using soil, but run non organic nutrients in it, PH your solution to 6.5 and you should have no problems. Soil doesn't need the high levels that coco or hydro does either as soil retains nutrients. 500-650 ppms works about the best.
Looks like cal/mag deficiency not a ph issue. And he's rtight those soil PH meters are worthless. The moister meter in it however is handy. With soil its hard to read PH. The best method is to water to runoff and test the run off. If the water/solution goes in at 7.0 it should come out about 6.7. More than a .5 difference means your too acid and ph needs to be raised. In soil, you would use garden lime or dolomite lime. You can mix a tablespoon of lime in water ( most won't disolve, thats ok ) just mix it well and pour it quickly over the surface then water it in.
And if your using soil, but run non organic nutrients in it, PH your solution to 6.5 and you should have no problems. Soil doesn't need the high levels that coco or hydro does either as soil retains nutrients. 500-650 ppms works about the best.
Looks like cal/mag deficiency not a ph issue. And he's rtight those soil PH meters are worthless. The moister meter in it however is handy. With soil its hard to read PH. The best method is to water to runoff and test the run off. If the water/solution goes in at 7.0 it should come out about 6.7. More than a .5 difference means your too acid and ph needs to be raised. In soil, you would use garden lime or dolomite lime. You can mix a tablespoon of lime in water ( most won't disolve, thats ok ) just mix it well and pour it quickly over the surface then water it in.
best of luck 
