How come the Ph will change?

[kdspecial]

I have noticed that when I mix my water and nutes I will test the Ph. and bring it to desired measurement. The next day when I test it again I notice it drops a couple points. I check cal on the Oakton tester Pen and its perfect.

I've read on the forums to always check and re-check the Ph again and again. Does the PhUp/Down just disappear and disolve in the water? should I even bother to set the Ph of my water a day ahead of using it,or before i leave it to sit for a few days?

I use a One Gallon plastic Jug that is similar to a big Jar(Science Jug) with a plastic lid not sealed.

I'm using
Botanicare Pure grow pro Grow/Bloom
GroteK Ph up/down
Bio-Genesis High-Tide

Any help is greatly appreciated.

kd_special

kdspecial Reviewed by kdspecial on 12-14-2006. How come the Ph will change? I have noticed that when I mix my water and nutes I will test the Ph. and bring it to desired measurement. The next day when I test it again I notice it drops a couple points. I check cal on the Oakton tester Pen and its perfect. I've read on the forums to always check and re-check the Ph again and again. Does the PhUp/Down just disappear and disolve in the water? should I even bother to set the Ph of my water a day ahead of using it,or before i leave it to sit for a few days? I use a One Rating: 5

[BlueBear]

Let the water sit for a day then mix the nutes if that is what your not doing right now. Some water will have a PH drop after sitting for 24 hours.
Adieu

[Perp]

The plant takes up the nutes at different rates which will cause ph fluctuations.

[stinkyattic]

Does the PhUp/Down just disappear and disolve in the water? should I even bother to set the Ph of my water a day ahead of using it,or before i leave it to sit for a few days?

The reaction between the pH up/down and the acids may not be instant... especially since you're using organics... I'd pH it and then use it right away. One thing you don't want is to let mixed ferts sit in just water where they can interact chemically.
Another reason that I am careful to start with SOIL at the right pH so it's not such a delicate operation. It's all about the humic acids, baby!

Oh yeah and what bluebear said, let the water sit and equilibrate with the atmosphere BEFORE adding ferts.

[justaseed]

are you groing soil or hydro. if i understand right you are mixing nutes and letting them sit for a few days and using it to water your soil/soilless plants. if that is the case this is a big nono. it says right on most fert bottles to use the ferts after you mix with water and discard the leftovers. saving the leftovers for watering a few days later can cause problems that you don't want to deal with.

if you are growing hydro just ignore my rambling.

[kdspecial]

Cool thanks for all the help guys and Gals.. I was mixing before hand then letting the water sit then Phing. From now on I will let the water sit for a day or two then add nutes and PH it right before use.

Thanks for the tips,,

I will be sure to discard the left overs,,,,

kd_special

[harris7]

i've acutely found odd pH changes in my water bottles.

I let them all sit for at least 24 hours at about 30 C
The water is all in 4L mil jugs (but ones that never held milk)

So if i pH my water to 6.4 and use it. a few days later i test it again the pH often goes up above 7. I find this very odd. Is it related to the plastic? is plastic basic or something. or could this be due to the reasons above:
-acids reacting slowly
-pH of water just changing with time as blue bear said

[dusto2k3]

The water is all in 4L mil jugs (but ones that never held milk)

Is this important? I use many 1 gal containers that i clean after i drinks me my milk. Is this bad?

[stinkyattic]

The water is all in 4L mil jugs (but ones that never held milk) a water jug rinsed well 3 times with warm water, as long as ther was nothing crusty and gross dried onto it, is fine even if there was milk in it at one time

So if i pH my water to 6.4 and use it. a few days later i test it again the pH often goes up above 7. .....
Is it related to the plastic? .....
or could this be due to the reasons above:
-acids reacting slowly yes

The plastic material that milk jugs are made of, polyethelene, is ridiculously nonreactive chemically.
My lab requests that all water samples be sent in LPE, LDPE, or HDPE containers only... not even glass!
In fact, glass is more reactive.
Micronutrients, Cu in particular, form chemical complexes on the surface of the glass that can only come off at a very low pH.
If you are pH ing your water and it returns above 7, my first insticnt is to say that you have something in there acting as a buffer, such as CaCO3. Very common in surface waters and groundwaters.
Now, I wish my boss were around to explain the various equilibria that Carbon has with water... but atmospheric C goes into water and does a number of things, like forming carbonic acid, Carbonate ion, etc. I believe that if you have Calcium in your water (which is virtually always the case to some extent) you will get some level of CaCO3 but I think it depends what form the Ca took... Ca+n ion... whatever charge... anyway uh.... yeah.... Im'a go shush now.

[dusto2k3]

Thanks for the info stinky...