That is quite normal especially if the plants are eating more than drinking, just like when you add nutes to the water the ph goes down so if the plant absorbs more nutes than water your ph should rise and now if the plant drinks more than eats it should lower a bit, there are other causes that make ph fluctuate but a point either way is normal. That is where ec meters come in very useful.

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I have never grown marijuana or intend to. Anything I post is knowledge gained from reading, not personal experience. Any pictures I post were aquired on the web or are fakes.