Getting some brown dots on a couple leaves on my p...

lower your feed for a week, probably nutrient burning if you used canna 20 years ago, never had problems with it, just don't use too much

I believe its calcium and manganese defiencies. Calcium for brown spots and manganese for black spots. Your leaves are cupping which is a sign of heat stress. Your gonna need better ventilation and more food!

Looks like your growing nft (nutrient film technique) style do you cover the roots and do you keep the nutrient reservoir chilled i know in nft it's better to run cooler water around 18degree c in nft

Your ph is fine. Check out @bigdaddyk he does dwc and his ph is the same as yours. And his plants are always on point. I do t know enough about you nutrient line except it says it has micros. So I’d doubt it’s a deficiency. You might try raising the light a little to relieve the stress on the plant. It’s showing a phosphorus burn so you should probably cut back on the nutes a little. The only other potential issue I see is the roots are not getting enough air or your watering the roots too often that’s why the leaves look puffy

Do you notice how many leaves have the edges curling upward? That's a clear sign that your pH is way off. I had that same thing happen to me last grow, you can check my first diary, I had those symptoms most of the grow until I started measuring pH and correcting it. The correct range for hydro is 5.5 to 5.8, having it a little off is fine, but yours is too much out of range; no it's not just a little, because the pH scale is logarithmic, what this means is that 6.5 pH is 10 times more alkaline than 5.5. Once you correct that, you will see a healthier plant almost overnight.

You're PH is a little high for hydro you've probably locked out some nutes which are better absorbed at a lower PH - Try looking here it will give you a better understanding !!http://www.growweedeasy.com/ph#hydroponic-soilless-pH Hope this helps