PJ Diaz
Well-Known Member
In the process described, carbonates are converted to carbonic acid, which is then converted to CO2; not in the order which you are suggesting.
Why is the PH of my mixed Canna Coco nutrients going up?
- Thread starter Jurassicbark
- Start date
Jurassicbark
Active Member
Yes, I am using tap water that comes from a neighborhood water system (3 wells). I don't have the water quality report handy, but the water is not especially hard.You neglected to mention what water you are using and if tap water it can have free ions that react fast with your pH down but have carbonates that aren't reacted right away that release more ions over time to cause the pH to go up again.
I've done the experiment in the past to make sure this isn't just a theory but an actual thing. Being a chemist who's forgotten most of it but can still figure shit out I was curious too tho I only use RO or distilled water to prevent things like this interfering with my grows.
Take a litre or a gallon, the volume doesn't really matter, of your water and pH it to what you want it for your plants. Let stand overnight or a day or more and check the pH again. If it's gone up then there's your answer. Things like carbonates will dissolve to their pH point and remain stable. Then you drop in an acid to reduce the pH which causes more to dissolve to get back to their equilibrium and the pH rises.
You could fill a container the same size you mix your nutes in then check pH once a day and add more pH down to hit target until it remains stable. Keep track of how much pH down was used to reach that point then when you you start with fresh water add your nutes first then add the amount of pH down from the experiment and the whole thing should remain stable over time unless it's something in your nutes that reacts as I described the water test. If that's the case you may want to think about using different nutes.
Many years ago I got some of the AN pH Perfect nutes and using RO water never think about pH either in DWC or pots full of ProMix HP. They make a coco version too.
Try that little experiment and see if that's it.
Also it could be that those nutes are supposed to be at the pH it keeps returning to so has buffers in it so it does that on purpose.
What you say makes sense, so the question is whether I can continue to PH the nutrient solution before each feeding, which seems to be working, or attempt to stabilize the PH as described above.
This is 48 days since sprouting, 51 days from seed. The lower leaves betray the PH problem I was having before buying a better quality PH meter.
I use 10 2700K CFL bulbs until flowering (Northern Lights Auto) then add an AgroMax RAW 65 3000K LED until harvest.
OldMedUser
Well-Known Member
Old lower leaves like those should just be removed. They aren't getting enough light to produce food for the plant so it scavenges mobile nutes from them and lets them die off. Often mistaken for deficiencies or pH issues but just natural things plants do. The rest of the plant looks very healthy and budding up fine so I wouldn't be fretting about it much.
Removing some of the tiny buds down below is also a good idea. They'll never amount to much and the energy used to try and grow them is better spent making the upper ones bigger. Less popcorn, more cola!
medidedicated
Well-Known Member
Nice thread, very informal. I tried the test one mentioned and after 4 days the ph went up by .2 . I used tap and gh nutes and ph down for my tap of 8.0+ and .5ec. Never knew this happened but that is not too bad.
I was told no need to wait after adding ph down or up before measuring which this thread explains why they say to indeed wait and test towards the end of that batch of nutes.
Does this also explain on the tech side of things why my meter drifts up in readings when sitting for a few minutes in solution? Or is it also chemistry at work? Is it ok to just take a brief reading or is the latter reading the true reading?
My run with tap went great but curious after reading this. I do water thoroughly/frequently each time avoiding different rootzone levels and use an accurate groline meter by hana and calibrate it.
I was told no need to wait after adding ph down or up before measuring which this thread explains why they say to indeed wait and test towards the end of that batch of nutes.
Does this also explain on the tech side of things why my meter drifts up in readings when sitting for a few minutes in solution? Or is it also chemistry at work? Is it ok to just take a brief reading or is the latter reading the true reading?
My run with tap went great but curious after reading this. I do water thoroughly/frequently each time avoiding different rootzone levels and use an accurate groline meter by hana and calibrate it.
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OldMedUser
Well-Known Member
It can take a while for all the pH down to react so a reading an hour after mixing may be higher if there is un-reacted carbonates left over or the reaction hasn't completed. If the mix isn't needed right away leaving overnight then testing would make sure everything has reached equilibrium and you'll get it's true reading. I'll have an airstone going in my jug of nutes to have constant mixing which will greatly shorten the time it takes to complete.
The meter reading should remain stable if the sol'n is stable so left-over carbonates could be present raising the pH slowly. Try the same thing in some pH 7 calibration sol'n and see if it stays on 7.
I'm curious about how you avoid different rootzone levels when watering. Or what that even means.
OldMedUser
Well-Known Member
There really shouldn't be anything in city tap water that need filtering and if there is it would likely be organic and wouldn't affect the pH. We filter our tap water from the dugout down to 5µ and if I fill a white pail and let sit overnight I can see a thin layer of sediment on the bottom. Standard RO systems come with a 5µ pre-filter so I'm having a 1µ filter first in the system I'm setting up then a standard carbon filter followed by a carbon filter that will filter down to 0.5µ before the water goes thru the RO membrane. More to help keep the RO membrane from plugging up than anything else.
It sounds more like buffers in the nutes you use causing this than the water itself but I'm not certain.
medidedicated
Well-Known Member
It can take a while for all the pH down to react so a reading an hour after mixing may be higher if there is un-reacted carbonates left over or the reaction hasn't completed. If the mix isn't needed right away leaving overnight then testing would make sure everything has reached equilibrium and you'll get it's true reading. I'll have an airstone going in my jug of nutes to have constant mixing which will greatly shorten the time it takes to complete.
The meter reading should remain stable if the sol'n is stable so left-over carbonates could be present raising the pH slowly. Try the same thing in some pH 7 calibration sol'n and see if it stays on 7.
I'm curious about how you avoid different rootzone levels when watering. Or what that even means.
Sorry, was replying fast and moved on. Rootzone, I started out reading to water according to volume and using a runoff tray to determine that which was just nonsense, unless I read something wrong. I do not think I did. I think you should water the hell out of it so it flushes out the bad and replaces it with fresh solution.
Then when it is in flower, needs to be watered twice a day and I am thinking it might need a third watering. Large dry backs raising the EC, salt build up. Roots uptaking a select set of nutrients, changing the PH and nutrient content ratio a little bit.
Watering thoroughly was essentially what solved my first nute deficiency in coco. Maybe switching to tap as well. This is what I meant, anyone please correct me where I am wrong, here to learn as much as I can.
PJ Diaz
Well-Known Member
Calcium in city tap water doesn't affect the ph?
medidedicated
Well-Known Member
I know it is helping be the reason I never needed to supplement calmg in coco as of yet. Lovin that!
PJ Diaz
Well-Known Member
I grow in coco, use RO as my base water, and also don't add cal/mag. You shouldn't need cal/mag in coco ever, if you are running quality nutes and irrigating properly.
OldMedUser
Well-Known Member
Of course it does but it doesn't come thru as chunks or crystals that can be filtered out with anything other than RO. When you dissolve a mineral salt in water it dissociates into an ionic form much smaller than even a 0.5µ filter can catch.
I suggest you research some basics about water chemistry so you'll have at least a minimal understanding about how all this works.
medidedicated
Well-Known Member
I remember being days away from getting a system then reading threads of what seemed to be credible growers saying the Ro was their issue and they had similar looking leaves to mine, fishbone look in coco.
The OP’s were suprised the extra care of RO turned out to be their issue. Then again all grows are slightly different to others. Good to know though, means a lot to hear it from someone whos been around. That is what shaped what I practice today.
I still vote tap water for being so cheap, easy and effective. I buffer/prepare my own coco too for best results which may be the key solution tap or RO. Do you use pre made coco?
J. Rocket
Well-Known Member
theres a fair bit of...bits in my city water.There really shouldn't be anything in city tap water that need filtering and if there is it would likely be organic and wouldn't affect the pH. We filter our tap water from the dugout down to 5µ and if I fill a white pail and let sit overnight I can see a thin layer of sediment on the bottom. Standard RO systems come with a 5µ pre-filter so I'm having a 1µ filter first in the system I'm setting up then a standard carbon filter followed by a carbon filter that will filter down to 0.5µ before the water goes thru the RO membrane. More to help keep the RO membrane from plugging up than anything else.
It sounds more like buffers in the nutes you use causing this than the water itself but I'm not certain.
particulate.
perfectly healthy, never hurt the plants, just dicked with my dtw res ph.
used same ph down and nutes from same bottles.
only change was going from a final filter of 1.0micron to the 0.5micron.
OldMedUser
Well-Known Member
This is why I can't understand the fascination with coco. Just seem like a lot more hassle than peat-based mixes like the ProMix HP I've been using the last 15 years or so since Sunshine Mix #4 was replaced by it locally. Very happy with the switch tho SS#4 worked really well with added perlite. HP has plenty of that and works fine straight out of the bale.
A decent sized plant in 4gal of HP only needs watering every 3 or 4 days and I go through a whole grow without having runoff. With RO water and AN 3-part pH is never a concern and there's enough Ca in it that I don't need to add calmag but do at about 1/4 of what it says on the jug of it.
With coco it seems multiple waterings a day do the best and that's just too much like work for me. Some people do seem to like to fuss with their grows so I guess coco is right for them. If I could plant a seed then come back a few months later to find it all cured and bagged up I would be in pot heaven for sure!
medidedicated
Well-Known Member
Nice, when I try out soil again I will be sure to check those brands out. I hand watered all my coco days and only just now saying next time, auto feed is a must. Cannot imagine the relief of just canopy/vpd management and refilling a rez.This is why I can't understand the fascination with coco. Just seem like a lot more hassle than peat-based mixes like the ProMix HP I've been using the last 15 years or so since Sunshine Mix #4 was replaced by it locally. Very happy with the switch tho SS#4 worked really well with added perlite. HP has plenty of that and works fine straight out of the bale.
A decent sized plant in 4gal of HP only needs watering every 3 or 4 days and I go through a whole grow without having runoff. With RO water and AN 3-part pH is never a concern and there's enough Ca in it that I don't need to add calmag but do at about 1/4 of what it says on the jug of it.
With coco it seems multiple waterings a day do the best and that's just too much like work for me. Some people do seem to like to fuss with their grows so I guess coco is right for them. If I could plant a seed then come back a few months later to find it all cured and bagged up I would be in pot heaven for sure!
The fasination for me is the fact that I seen and personally grew soil, not that hard, but coco really does grow aggressively, daily. In my words it is like the media takes care of itself at that. Some may weigh the same end results but I get to get there faster.
Already looking at stronger lights 2200 ppfd since everything else has been figured out. Just want more power and space and yield, the fasination of growing period lol.
PJ Diaz
Well-Known Member
My question was rhetorical.Of course it does but it doesn't come thru as chunks or crystals that can be filtered out with anything other than RO. When you dissolve a mineral salt in water it dissociates into an ionic form much smaller than even a 0.5µ filter can catch.
I suggest you research some basics about water chemistry so you'll have at least a minimal understanding about how all this works.
PJ Diaz
Well-Known Member
What is "pre made coco"? My point was that if your nute solution is properly balanced, then. you don't need calmag. That said, there are many nute lines, which are specifically formulated to get you to buy as many bottles as possible. Chances are if your nute line sells a bottle of calmag, then their base nutes simply aren't properly balanced.
PJ Diaz
Well-Known Member
The only work involved is in setting up the auto watering system. After that, it's just refilling a res and dumping runoff once a week.
medidedicated
Well-Known Member
Coco/pearlite ready to put in a pot and go. Im all with ya on that, just switched to a one part maxi. For context, I started out thinking I had to go by everything mj coco says to do to quickly find that my own feed through GH is enough. And now possibly with pre made coco?
idk what else to call it. What are your thoughs on growing in unbuffered coco? Or coco that is hungry for calmg or claimed to be buffered but is due for a recharge. That isn’t a gimmick too right? Genuinely wondering.