Imhigh85
Well-Known Member
Yes because you could pH the water today and tomorrow the pH will be different you can mix up your nutrients and keep it ready but just pH what you are going to use
Slinks
Well-Known Member
the nutrients react with the ph up or down creating salts and causes ur ph to go back up normally. thats why you need to check ur ph before feeding or at least once a day if using a resevoir. that being said for first few years of covert growing I didnt check my resevoir ph for weeks n weeks n had no problems. soil is very forgiving.
Scientific
New Member
Um, but isn't that a good thing? You're giving time for everything to equilibrate (i.e. for the pH Down or pH Up to interact with the buffers and stabilize, which can take some time).
I don't think there's any problem with mixing nutes a day or two in advance.
Imhigh85
Well-Known Member
Ph up and PH down are only active in your water for a few hours then it starts to go back to its normal pH so if treating his nutrient water now 4 pH he will just have to do it again when he goes to water the next time this is the reason I suggested that he only pH what he is going to use nutrients are flying to be mixed together but you don't want them to be left for more than 7 to 10 days mixed
Scientific
New Member
Hmmm, that runs counter to everything I learned in chemistry. If you add phosphoric acid (the main active ingredient in pH Down) or lye (the main active ingredient in pH Up), those chemicals don't go anywhere, and being very a powerful acid or base, they don't stop working either.
Commercial fertilizers are made with buffers that stabilize the pH, so if you're seeing a change in pH, it's most likely just the time delay for the buffers to work.
> you don't want them to be left for more than 7 to 10 days mixed
That is my understanding as well.
Imhigh85
Well-Known Member
Google does water change pH over time
It would surprise you the answer
It would surprise you the answer
Slinks
Well-Known Member
in my experience with hesi nutes n desalinated sea water from my tap. my ph fluctuates between 5.5 after an hour of mixing nutes n ph down - to about 7 every 24 hours.
Imhigh85
Well-Known Member
I don't pH my water it doesn't need to be done after I add everything it's it's at 5.8
Slinks
Well-Known Member
if I leave it longer I get almost 8 which is ph of my water out tap. therefore the water n nutes must be breaking down the ph buffer
Slinks
Well-Known Member
are you measuring the run off from ur plants?
Imhigh85
Well-Known Member
No I'm not measuring the run off either I have been doing this long enough with the same kind of setup that I have pretty much gotten it down to a science I know what time of year my water fluctuates
Imhigh85
Well-Known Member
It's actually the the carbon dioxide in the air and what gets trapped inside the bottle that actually causes the change
Scientific
New Member
Sorry IH, I don't mean to be contrary, but CO2 is only present in very small quantities in air--not enough to significantly affect ph, especially of a buffered solution.
Imhigh85
Well-Known Member
If you say so but I know that I watch the water constantly change day today
Scientific
New Member
Sure, water that is not in stable state will change pH until it equilibrates with both its environment (temperature, gases in the air) and the chemistry of any added substances stabilizes (e.g. buffers).
Scientific
New Member
I can't argue with your particular experience, of course.
The chemistry of aqueous solutions can be complicated!
One more thing: the pH water of water that is fairly pure can change very easily (from CO2 that is present for example, as you noted, creating weak carbonic acid), and readings can change as temperature changes (though the effect is not large). After buffers are added and had time to work, the pH is much more stable (which is exactly what the buffering chemicals are there for).
At my first job out of college one of my main responsibilities was preparing about 100 liters of ultra pure water for a research laboratory every day, so I got know water chemistry pretty well.
Imhigh85
Well-Known Member
Because pure water has no chemicals or minerals in it to react with the nutrients and the pH Up and Down
