Can't Figure IT OUT!!

I noticed some additional posts, so I thought I would drop an update. I agree w/ MrGreen that it is a nute lockout due to low pH. I have been pHing my runoff religiously the past 3 weeks. When I initially started, it was reading around 5.6-5.7. I initially did a typical, by the book flush... It didn't help one bit. I used pH=7 warm water (~4 gal), followed by pH=9 warm water flush (~2gal) (adjusted w/ potass hydrox, pH up) for net 2.5 gal medium. I used FF Happy Frog soil, and have used Botanicare Pro line base nutes w/ recently adding CalMag, Liq Karma in the past 3 weeks. Problem seems to persist, although I am not getting any yellowing of fan leaves prior to copper spotting. New foliage looks green and healthy. My runoff has slowly increased to 5.9-6.1, but that is as high as I have gotten it since initial testing. All nutes added have been pHed using appropriate chemicals @ ph=6.8-7.0. Temps are a little low (65 during night), but RH is perfect. Ive also added CO2 since flowering at around 1500ppm, since I have no In or Out vents.

JN811 said:

Where did you buy these ph up chrystals?

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You can find them at most hydro shops. If you don't have one locally, I know you can order them from www.atlantishydroponics.com. They have Ph up and Ph down crystals. I bought both (a bottle should last at least several years because you only need a TINY amount of them to get the desired effect), but I've never needed to use the Ph down. I guess Hydro growers would use that more, but I'm strictly a soil guy and have only encountered issues with low Ph.