rkymtnman
Well-Known Member
Here is someone explaining in better detail and understanding then I was able to explain why ph can drop during flower and rise in veg normally.
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Something for you to consider mate, especially if your plants are looking healthy and no obvious signs of other problems.
The plant itself may be the largest contributor to pH changes in the nutrient solution.
The solution is made up of positively and negatively charged ions, called cations and anions. As the plant takes up these charged nutrient ions it gives off an H+ or OH- ion via the roots in order to keep the charge balanced between the solution and the plant tissue.
When a positively charged cation, like K+ is taken up, the plant puts out an H+ ion.
When a negatively charged anion, like NO3- is taken up, the plant puts out an OH- ion.
pH is a measure of the H+ concentration, so you can see how the plant can affect it depending on what nutrients it is most using at any given time in the grow.
For example, during the flowering period cannabis uses relatively more K+ than it did during vegetative growth. So the plant is putting out more H+ ions, which will cause the pH to drop.
Conversely, during vegetative growth the plant is using more N, which is in the form of NO3- mostly in hydro nutrients. So the plant is putting out alot of OH- ions, which will tend to increase the pH.
makes sense to me. another reason why i love drain to waste!!