Testing soil ph is easy

[sproutco]

Hello all,

Can those pH meters be used in sticny dirty slimmy bubbled tea with accuracy?

minds_I

yes but don't scratch the electrode.

 

[the cult]

Once the buffers are gone from the nutrient solution and its sitting at a certain ph, you might find that just a drop of ph down drastically will change the ph.

what causes the buffers to leave the solution? could you pls explain basically what happens?

and just out of curiosity, how do hydrogrowers maintain a ph of 5.2 with buffers in? or are buffers in nutes for hydro that acidic?

many thanks for your help, sproutco!

 

[sproutco]

what causes the buffers to leave the solution? could you pls explain basically what happens?

Its logarithmic the way the ph goes down. So its not like it decreases at the same pace. At first, adding a bit of acid would decrease the ph only a little. Some of the carbonates or the buffer are "eaten" and neutralized. They no longer exist. Here is an acid hcl or hydrochloric acid. It reacts with the carbonate buffer (caco3). Carbon dioxide (co2) and water (h2o) are formed. CaCO3 + 2HCl → CaCl2 + CO2 + H2O. As you add more acid, the ph begins to drop more rapidly at a faster and faster pace. Eventually no carbonates left. They are no longer "active". Then the ph would change dramatically with just a little acid. Having some carbonates in the water can be beneficial to keep the ph from droping too much. Some growers only neutralize a portion of the carbonates and leave some as a buffer. This would be especially important if your fertilizer has a acidic reaction in the soil or when nutrients enter the plant root and subsequently release acidifying h+ into the soil/nutrient solution (like ammonia nitrogen does.)

You can see a logarithmic curve is not straight and does not decrease at the same rate but curves at a faster and faster rate. Eventually it just dives down.

 

[the cult]

thanks sproutco, but i dont get how my ph rises thanks to the buffers, but they are still only a drop away from going way down? as i said, with a low ph of 5.2-5.4 it will increase to about 6.2 over some time (buffers in the nutes), and if i try get it back it drops far below 5, often to 4 or even less. its like the buffers dont really change the ph cos it requires so little to drop on a biblical scale!
so im not asking why the ph drops so much between values of 4-5 compared to between 5-7 but rather... ill give you an example, i have 3 gallons of water (tap water, ph of 7.5), i add nutes, ph is 6.8 after nutes been added, i add 1 ml of ph down, ph is 6.5, 1 more ml, ph is 5.9, 1 more, ph is 5.3 - im pleased. i leave water with nutes for 1 hr, check back on it, take another reading, ph has risen to 6.3, i add 1 ml or even less, and ph is suddently 4.3.

i dont understand why it drops so much from 1 ml (or less) this time, it doesnt make any sense to me?

sorry for such a long explanation.

furthermore,

just thinking, iv seen better results myself with water having a ph of the same that hydrogrowers would use (in bloom phase, 5.2-5.3,) and i grow in soil and/or coco, this i think would be because the soil is completely empty of nutrients and doesnt react much with the water, thus resembling a hydro system a bit.
i veg i have experienced nute lockout/def using such a low ph, but rather aimed at 5.8-6.0, but for bloom phase its done a great deal on yield.

i cant say i in any way made a scientific study, or something even resembling science, and i dont know all the technical details (as you realise from this post even), but can you offer any opinion, experience, details on this? im feeling like im one of the few actually going this low in soil and coco (although eg canna recommend ph of 5.2-6-2 for their soil nutes).

anyway, thanks again for your time.

 

[sproutco]

Real problems start to occur below 5 and above 7 ph.

 

[sproutco]

Added a few pictures to spice things up and suggested ec ratings in ppms for the pour through or leachate test.