Ph Changed in pre-mixed nutrients overnight

[hot_box_enthusiast]

TL;DR - Mixed 30L with 3 part and CalMMag, ph adjusted it from 5.7 to 6.2 and left overnight. this morning pH had dropped to 5.8. Why?

I often mix my nutrients the night before feeding. Sometimes, due to individual plant needs, the mixed nutrients might be used over the next 1-2 days. I have never checked the Ph the next day before feeding, but did so today to double check with my notes.

Last night I mixed 30L of Advanced Nutrients phPerfect 3 part mix (3ml/l = 75%). I added 1.25ml/gallon of CalMax (nothing unusual here, this is my normal routine). This gets me to 1,350ppm (500ppm scale) and usually a pH around 5.7. I used pH+ to adjust to 6.2 (I vary pH between feedings). This morning when I checked, it had naturally dropped to 5.8. This was quite a surprise, and also begs the question what happens when it sits around for another day (I will find out tomorrow).

So;
Is this normal for pH to drop overnight after mixing?
Is it OK to pre mix nutrients like this?
Is there a maximum number of days pre mixed nutrients can "sit around" before being used?

 

[Mak'er Grow]

Its possibly the phPerfect nutes...they adjust themselves...think its this video that shows 3 different ph waters all change to same value.

 

[OldMedUser]

TL;DR - Mixed 30L with 3 part and CalMMag, ph adjusted it from 5.7 to 6.2 and left overnight. this morning pH had dropped to 5.8. Why?

I often mix my nutrients the night before feeding. Sometimes, due to individual plant needs, the mixed nutrients might be used over the next 1-2 days. I have never checked the Ph the next day before feeding, but did so today to double check with my notes.

Last night I mixed 30L of Advanced Nutrients phPerfect 3 part mix (3ml/l = 75%). I added 1.25ml/gallon of CalMax (nothing unusual here, this is my normal routine). This gets me to 1,350ppm (500ppm scale) and usually a pH around 5.7. I used pH+ to adjust to 6.2 (I vary pH between feedings). This morning when I checked, it had naturally dropped to 5.8. This was quite a surprise, and also begs the question what happens when it sits around for another day (I will find out tomorrow).

So;
Is this normal for pH to drop overnight after mixing?
Is it OK to pre mix nutrients like this?
Is there a maximum number of days pre mixed nutrients can "sit around" before being used?

Your mistake is trying to adjust AN nutes. Trust the technology and just forget about pH. I've used AN for 20 years so long before pH Perfect was introduced and I didn't want to use it at all but finally had to as I ran out of my gallon jugs of the older stuff. I use RO or distilled water only for DWC or soil/soilless growing and never, ever check pH. Never have pH related issues either.

 

[IrkinBollikans]

Not to hijack this thread, but using maxibloom, I've been noticing my pH being higher the day after I mix my reservoir. Any help appreciated

 

[OldMedUser]

Not to hijack this thread, but using maxibloom, I've been noticing my pH being higher the day after I mix my reservoir. Any help appreciated

If you are using tap water then that's a normal thing so change to RO and have steadier pH. Change to a non-Monsanto type of nute like AN for even better results.

 

[hot_box_enthusiast]

Thanks for the replies.

My understanding is that different nutrients have different optimal uptake ranges (for cannabis these are mostly met between 5.5 to 6.5). As one example, both Cal and Mag prefer 6.0 or higher. Since AN mixes around 5.7, it seems that when I am adding CalMag that bumping pH up to 6.1 is a good idea to allow for better uptake. (I also allow feed at 5.7 without adjusting... like I say I am giving a range to try and maximize chance for nutrient uptake).

As far as RO, the tap water here is great (0ppm, Ph just slightly acidic). I've spoken with long time local growers and they don't bother with RO systems here.

 

[hot_box_enthusiast]

Its possibly the phPerfect nutes...they adjust themselves...think its this video that shows 3 different ph waters all change to same value.

My understanding is that they will take different *starting* pH and get them to the same end point as per the video, however it seems after mixing I would be able to adjust? I could be wrong here though. Its funny.... so many places in learning about this hobby such a big deal is made about pH so I am trying to really dial it it, then I find out maybe just set it and forget it

 

[OldMedUser]

Thanks for the replies.

My understanding is that different nutrients have different optimal uptake ranges (for cannabis these are mostly met between 5.5 to 6.5). As one example, both Cal and Mag prefer 6.0 or higher. Since AN mixes around 5.7, it seems that when I am adding CalMag that bumping pH up to 6.1 is a good idea to allow for better uptake. (I also allow feed at 5.7 without adjusting... like I say I am giving a range to try and maximize chance for nutrient uptake).

As far as RO, the tap water here is great (0ppm, Ph just slightly acidic). I've spoken with long time local growers and they don't bother with RO systems here.

I doubt very much that your tap water is 0ppm Even good RO systems don't get to 0 unless brand new and use a de-ionizing filter at the back end. Real low is good tho and the RO I just bought is at 38 so I'll be calling the manager at our local co-op to tell him it's time to redo his filters. All the nutes have their optimum sweet spot for max absorption but still absorb very easily to the plants at all but way out ranges. There's no exact pH that is going to make them all absorb at the max nor is that needed for great growth. Some people drive themselves nuts trying to stay on point when the plants themselves change the pH around their roots to get what they need.

Before the AN nutes were pH Perfect my DWC pH would run up to 6.4 after 3 days so when I topped up and checked I'd add some nutes to stay on target and a few drops of 96% sulphuric acid to bring the pH down to around 5.4 then 3 days later it would be back up to 6.4. That was actually good as it gave all nutes some time in their optimum range. After 50 grows like that and half of those using the pH Perfect it doesn't really seem to matter.

My understanding is that they will take different *starting* pH and get them to the same end point as per the video, however it seems after mixing I would be able to adjust? I could be wrong here though. Its funny.... so many places in learning about this hobby such a big deal is made about pH so I am trying to really dial it it, then I find out maybe just set it and forget it

With the pH Perfect there's no need to adjust the pH and it's just self-defeating as it has it's set point that the scientists at AN have determined to be optimal for cannabis. It will just return to what it wants unless you keep adjusting and finally use up the buffers in the nutes. If you're going to do that them might as well use any nutes that do need pH adjustment.

 

[hot_box_enthusiast]

I hadn’t considered that the ph Perfect will keep trying to go to its “formulated” amount. I’m going to keep an eye on things as it’s interesting but won’t sweat things too much without reason.

 

[Ddrome15]

As a chemist, I can attest for the above statement. The pH perfect has buffers that cause resistance to pH change. If you checked immediately after addition and swirling, it may take a minute to readjust to its equilibrium.

 

[OldMedUser]

As a chemist, I can attest for the above statement. The pH perfect has buffers that cause resistance to pH change. If you checked immediately after addition and swirling, it may take a minute to readjust to its equilibrium.

Hello fellow chemist! Dipl. T, Environmental Chem, BCIT, Burnaby, BC campus, class of '89 at age 35.

I should have taken computer science or gone for a millwright's ticket then I might have some money.

I'm constantly trying to explain pH issues to folks but it's a much more complicated subject than most think. Especially when dealing with complex biological systems like plants. Equilibrium can take hours to achieve but most just mix it up and immediately check pH only to find it can change significantly in time if they let it sit and check again before use.

That's about all I remember from my schooling.

 

[piratebug]

Even the best pH meter won't ever be able to tell you what the actual pH of your mix is if you are using tap water and are trying to adjust the pH of your mix right after adding your salts. The reason for that is because any water that has a base greater than 0.0 ec / 0.0 ppm will cause the pH of that water to shift downward as many of the elements added to the water by your local municipality for delivery and health standards will begin to evaporate. That's why it is best to leave out tap water for 48 hours before testing its pH base because only by then will all the elements that usually rapidly evaporate out of the tap water will have done so after those 48 hours!

 

[OldMedUser]

Even the best pH meter won't ever be able to tell you what the actual pH of your mix is if you are using tap water and are trying to adjust the pH of your mix right after adding your salts. The reason for that is because any water that has a base greater than 0.0 ec / 0.0 ppm will cause the pH of that water to shift downward as many of the elements added to the water by your local municipality for delivery and health standards will begin to evaporate. That's why it is best to leave out tap water for 48 hours before testing its pH base because only by then will all the elements that usually rapidly evaporate out of the tap water will have done so after those 48 hours!

The only thing that's going to evaporate out of the water is chlorine and the water itself. There's not enough residual chlorine in municipal water to affect the pH. They may add some calcium sulphate if the water is below pH 7 to prevent corrosion of the infrastructure but other than filtering and adding a sterilizing agent like chlorine or chloramine and damn them all to hell, fluoride that's it. There is nothing that's going to evaporate and affect the pH either way. If chloramine is used then that's still going to be there too but it's not enough to affect the plants. Chlorine won't really harm anything either so it's not a problem. An airstone will get rid of chlorine a lot faster and add oxygen to the water. I run a stone in my jug of RO water for at least an hour before watering my plants to make sure the O2 level is as high as it can be.

Using hard water is a bitch to pH down. You add some to get it where you want and an few hours later it's back up. pH down again and again it goes up. That's because the free ions get used up by the acid then more form from the residual carbonates and up goes the pH. Pure water is the way to go to prevent problems.

 

[hot_box_enthusiast]

My Blue Lab TDS meter reads 0ppm from my tap.

 

[piratebug]

The only thing that's going to evaporate out of the water is chlorine and the water itself. There's not enough residual chlorine in municipal water to affect the pH. They may add some calcium sulphate if the water is below pH 7 to prevent corrosion of the infrastructure but other than filtering and adding a sterilizing agent like chlorine or chloramine and damn them all to hell, fluoride that's it. There is nothing that's going to evaporate and affect the pH either way. If chloramine is used then that's still going to be there too but it's not enough to affect the plants. Chlorine won't really harm anything either so it's not a problem. An airstone will get rid of chlorine a lot faster and add oxygen to the water. I run a stone in my jug of RO water for at least an hour before watering my plants to make sure the O2 level is as high as it can be.

Using hard water is a bitch to pH down. You add some to get it where you want and an few hours later it's back up. pH down again and again it goes up. That's because the free ions get used up by the acid then more form from the residual carbonates and up goes the pH. Pure water is the way to go to prevent problems.

I was not talking about chlorine or even monochloramine as neither of them really effect pH levels, but I was talking about natural occurring compounds and elements that come from the actual water source, and that are never filtered out by any city water municipalities unless they are extremely high, things like "carbonate, bicarbonate, and hydroxide compounds", which initial greatly increase tap waters pH by a minimum of 0.8 pH all the way up to 2.7 pH, and most of those things can take up to 72 hours to completely off-gas, which is why you will never accurately know what your tap waters pH is without letting it sit out for at least 2 days. It's like where I live, our water contains less then 0.1 ec / 45 ppm(s) of active elements and compounds, but right out of the tap its pH is 9.4, but after it's left to sit out for 48 hours the pH actually drops to 7.0, and then it pretty much stays there even after 21 days.

 

[IrkinBollikans]

If you are using tap water then that's a normal thing so change to RO and have steadier pH. Change to a non-Monsanto type of nute like AN for even better results.

I'm not a fan of the waste produced by ro systems. Would a normal faucet type filter do me any good?

 

[OldMedUser]

things like "carbonate, bicarbonate, and hydroxide compounds", which initial greatly increase tap waters pH by a minimum of 0.8 pH all the way up to 2.7 pH, and most of those things can take up to 72 hours to completely off-gas,

Those are all minerals and do not evaporate. If you distilled the water they would be the crust on the bottom of the pot.

You must have magic air at your place to reduce the pH as much as you claim just by exposing your high pH water to it.

I have a diploma in environmental chemistry with water/air quality being a huge part of my studies so I do kind of have a clue about what I'm saying.

 

[OldMedUser]

I'm not a fan of the waste produced by ro systems. Would a normal faucet type filter do me any good?

Those types of filters are designed to reduce metals like lead and cadmium and take taste/odor out of the water with activated carbon but don't remove things like carbonates that cause the pH to be higher than 7 so the ppm won't go down more than a tiny fraction if that.

How much waste water concerns you? If you just use an RO unit to make water for your plants it's not a heck of a lot. The better your tap water is the less waste there is too and some units get a 2:1 ratio of wasteure.

Our tap water comes from a dugout on my property so the water is free but around 400ppm and pH8+. The dugout is 50x80x4m deep so around 16,000 cubic meters or 4 million US gallons so have lots of water.

The waste water can always be used elsewhere like a garden so it doesn't all have to go to waste.