HELP! WHY IS PLAIN WATER SO HARD TO PH?
- Thread starter kngblnk
- Start date
One thing is, pH is a logarythmic scale, meaning it will take 10 times the amount it took to get from pH 7 to 6 to get from pH 6 to 5. Second thing is, plain water lacks buffers, mixtures of disolved salts that bind some of the acidity causing ions and prevent addition of acid from impacting the overall pH of the solution up to a point.
churchhaze
Well-Known Member
It's actually easier to change the pH of plain water. The pH of plain water is pretty meaningless. pH readings only becomes meaningful as ppm starts getting higher. It's also extremely hard to measure the pH of such a low concentration solution (pure water). This sort of explains the problems with measuring pH of pure water.
http://www.eutechinst.com/tips/general/16.pdf
Think of pH buffering like a seesaw. If you put 1 pound on one side, it will fall to that side easily, but if you put a 300 pound fat kid on each side, that 1 pound will no longer make a difference in which direction the scale tips. It will BARELY cause the scale to tip toward the 301lb side.
The 2 fat kids "buffer" the seesaw, so the 1 pound difference in weight no longer has any effect.
http://www.eutechinst.com/tips/general/16.pdf
Think of pH buffering like a seesaw. If you put 1 pound on one side, it will fall to that side easily, but if you put a 300 pound fat kid on each side, that 1 pound will no longer make a difference in which direction the scale tips. It will BARELY cause the scale to tip toward the 301lb side.
The 2 fat kids "buffer" the seesaw, so the 1 pound difference in weight no longer has any effect.
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Actually no. Buffers work on the principle of chemical equilibrium. It is a principle that states that a process that is in equilibrium will react to the change of a system in a way that cancels that change. For example, if I put some salt AB in water, two chemical reactions will happen. Salt will start disolving into ions, and ions will begin agregating back into a salt form. After some time ratios of salt and its disolved ions will be constant. If I added some other salt CB, thus increasing the number of B ions, rates of our initial reaction would change so that less of the salt AB was disolved, thus preserving the total ratios of salt AB and its disolved ions.
We can use that same principle to prepare a solution of acids and salts that will react in such a way that if acid or base is added to it, system will react in a way that it will negate the change in acidity.
You can think of buffers as a chemical storage of acidity/alkalinity. If acid is put in a system, its acidity is stored in a buffer instead of being released into the solution. If base is added, some of the stored acidity is released, again negating the change. Ofcourse, every buffer has its capacity and stops working once it is reached. That is why you can notice that sometimes you add pH up/down and see little change, but then add just one more drop and suddenly see a radical change.
We can use that same principle to prepare a solution of acids and salts that will react in such a way that if acid or base is added to it, system will react in a way that it will negate the change in acidity.
You can think of buffers as a chemical storage of acidity/alkalinity. If acid is put in a system, its acidity is stored in a buffer instead of being released into the solution. If base is added, some of the stored acidity is released, again negating the change. Ofcourse, every buffer has its capacity and stops working once it is reached. That is why you can notice that sometimes you add pH up/down and see little change, but then add just one more drop and suddenly see a radical change.
superstoner1
Well-Known Member
PH affects nutrient uptake via the roots. Ph-ing plain water is just a waste of time and chemicals, it does nothing.
superstoner1
Well-Known Member
The only need for pH is for nute uptake. ONLY. Plain water never needs to be ph'ed.
kngblnk
Member
right on!