Why does my ph'd water keep changing overnight?

So I ph'd my water to 6.5 and then checked it a few more times and it was right on, so I go to check it right before I water my plants like 1-2 days later and now the ph is back up in the 7.0's again, is it because of the air stones I have going in the water or is it just because it's sitting and evaporating, It's sitting in a trash can with no lid but does have several air stones going in it, any ideas? Also what are some natural ways to PH down the water, and how many have ever been told not to PH the water since it will change in the dirt and you should test the run off water, so should the run off water be the same ph you want or what do you go by?

I am too new to hydro to help, but hope for good answers. :0)

Good luck,

JD

My water and nutrients that are sitting in open buckets with air stones do the same thing.. Not sure why though.

Not adjusting your PH and letting the soil do the work is called "soil buffering" I'm not an expert but I think this would be more of a common practice when growing outdoors as the ground has better ability to buffer compared to plants in pots, but I do know people make their own "super soils" that require no feeding or PH adjusting of any kind from start to finish, Just not my preference.

I would recommend setting the PH of your water and nutrients every time before giving them to the plants if growing in pots/soil or any other medium for that matter, If you were growing outdoors in the ground you could get away with not adjusting PH I have done it before with no issues, this is why you can water outdoor plants with tap water and they do just fine, the soil straightens out the PH on its own.

IMO Don't bother testing the run off its more trouble than its worth, just adjust the PH of your water/nutrients going in and let the medium do the rest, I like to set my PH towards to lower end of the safe zone since PH tends to constantly want to rise in my experience.

From what I remember, the pH swings are from the movement of the water caused by the air coming from the air stones. I don't know scientifically why this happens but it is 100% natural.

If I take water straight out the tap and let it sit, the ph changes over the first day or two by a good amount. I believe it is theclorine evaporating out of the water. The ph will continue to change slowly for a few more days but not as fast. Idk why exactly

I've read water has dissolved Co2 which creates carbonic acid, lowering the ph. Exposed to air it dissipates.

But, that doesn't explain why it goes up after lowering the ph with ph-down. (I've seen that too.).

ryan1918 said:

So I ph'd my water to 6.5 and then checked it a few more times and it was right on, so I go to check it right before I water my plants like 1-2 days later and now the ph is back up in the 7.0's again, is it because of the air stones I have going in the water or is it just because it's sitting and evaporating, It's sitting in a trash can with no lid but does have several air stones going in it, any ideas? Also what are some natural ways to PH down the water, and how many have ever been told not to PH the water since it will change in the dirt and you should test the run off water, so should the run off water be the same ph you want or what do you go by?

Click to expand...

lemon juice will lower your ph

Doesn't PH change when the temperature of the water changes?

Yeah temp can affect ph, a lot of ph meters have that accounted for though. I'm pretty sure disolved oxygen affects ph.
Vinegar works as ph down also

az2000 said:

I've read water has dissolved Co2 which creates carbonic acid, lowering the ph. Exposed to air it dissipates.

But, that doesn't explain why it goes up after lowering the ph with ph-down. (I've seen that too.).

Click to expand...

What I read is that a bubbler drives off CO2 from the water. How I don't know. Sounds weird to me but that's what it said.

If you've RO filtered the water it will swing pH wildly, as there are few ions to stabilize.

If not RO then it's likely dissolved gasses causing this

alright thank you

Ph changes because the contents of the water changes rofl plants use part of the nutes as part run off over and over again larger res will slow the ph Flux the constant change of ph is due to the constant consumption of the water and nutes by the plant