Nutrient solution prior to feeding was tested at a pH of 6.7 and 615 PPM. The run-off from the feeding was measured at a pH of 8.8 and 1250 PPM. It should be noted, that the run-off tested was taken from the total run-off available, and not the earliest run-off possible. For the pH, I am thinking of feeding (next time) with a nutrient solution at a pH of 6.0 Is this too much/not enough of an adjustment, to get my run-off closer to the desired range of 6.5-7.0 (soil)? As far as the PPM, the grower that I got the clones from said that I wanted to keep my PPM below 800 for run-off. How do I adjust for this, or do I? I know that some will say that you do not need to adjust the pH of the water in soil; however, from all that I can read and from those I have spoken too, pH must be adjusted to prevent nutrient lockout. The grower was particular in noting this as the tap water here is quite alkaline. I am new and have plenty to learn, so as my grows progress, I may learn differently, but for now, I will be adjusting the pH of my nutrient solution to the recommended values.
Sure, check and adjust the pH of the solution you're feeding - why not? If you're using hydroponic nutrients you SHOULD be adjusting the pH of your solution to the desired range. The problem is that you are growing in soil and not in an inert hydroponic medium such as rockwool, perlite/vermiculite or coco. Of course your pH is going to come out much differently on the bottom end than the end it went in - it's soil. As your solution filters through your soil it's picking up dissolved solids and various types of organic matter. Testing the runoff of soil will have you chasing your tail. It is not an accurate measurement of anything - at all, whatsoever. The only time testing and gauging the pH or PPM of the rhizosphere is going to be accurate is when you're using an inert medium that contains zero nutrition or dissolvable solids. IMO if you want to use hydroponic nutrients then use an inert medium. If you want a soil garden then use organic fertilizers. My $.02c. J