PH is driving me nutts

Okay I Ph my water at 6.5 after adding my Grow big 2tbs per gallon once a week Before my next feeding I re check the Ph again now its up to 7.2 what the hell causes it to jump up after just setting for a week .and yes I recalibrate it at 7.0 solution just to make sure the Ph tester is working correctly .

pH of nute solution will continue to change if it sits. That’s why you adjust pH just before using it.
Even water will change pH as it sits.


Well slap me stupid no wonder thanks Drinkslinger I was about to lose it !!


Just to add to that, in larger automated hydro grows a sensor and doser is used to keep the ph in the desired range. As the plants consume the food and water at slightly different rates it can not only upset the nutrient ratio but also the ph.
So too you will need to adjust water especially with additives the longer it sits.
One other word of caution, if the solution sits for a while, re stir it generously as some minerals may fall out of solution and in some cases can be re constituted if only long enough to water with. Many people use a bubbler stone to both oxygenate and stir. You can also speed up dechlorination tjis way.

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Water when sitting out will absorb CO2 from the air.
So over time it will change the PH of the water upward.
Do a test and PH some plain water and then check it the next day and it will have risen back up.

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