Old Reviews stability of mixed nutes

[karlkutta]

Howdy Folks!
I thought I share this with you all. Would love some input as well.

I frequently have to pre-mix my nutes because I tend to be gone for a couple of days at a time (2-3 nights). When i can I mix right before watering and use all that I have, but when I know I will be out for a little bit I will pre-mix into my reservoir and water ~ 1 gallon to my various plants.

Currently I am growing in some old soil that really doesnt have much of anything left, i kind of treat it like coco but this post is not about that.

I started running into issues with ph stability after my nutes were sitting for a while. PH would be set where I needed it, but after 24 hrs it would be off the charts. I decided to find out exactly why. My setup is basically a 2 gallon plus reservoir and I have a wifi plug through which i can turn a pump on/off, set schedules etc.

the nutes i use are:
Tab Water source: Tab water (H2O)
MegaCrop (MC)
Canna PK 13/14 (PK) (if in bloom)
foxfarm gringo CalMag (cM)
Roots Organic HPK (HPK) (i just added this one to the list since I have it sitting around)

I am sure all nutes react differently, but in order to see which ones are stable I mixed some separately and started measuring them daily for PH.
I use an aquarium dripper style tester, it doesnt give me a digital readout but I feel this does give consistent results.
my observation:

Day # ----- H2O ----------- MC ----------- PK ------------ cM ------ HPK
day 0 -------- 7 ------------ 6.4-6.6 ------- 6.8-7 --------- 7 --------- 5
day 1 -------- 7 ------------ 6.6 ----------- 7-7.2 --------- 7.6 ------- 6.4
day 2 -------- 7 ------------ 6.6 ----------- 7-7.2 --------- 7.6 + -----
day 5 -------- 7 ------------ 6.6 ----------- 7-7.2 --------- 7.6 + -----


the tester I am using shows ranges between 6-7.6, i have a 2nd tester which shows 4-8 and while i dont like it as much, it shows very similar results and therefore I am confident the readings are fairly accurate.

my conclusion here is that while I know my plants need calmag, I will leave it out of the mix to ensure stability. When doing straight waterings I will add it to it since in the past I seemed to run into issues with it not being there.



TLDR: leaving calmag out of reservoir to keep PH at the sweetspot.

Edit: adding Roots organic HPK and Tab Water numbers. HPK was tested only after a few days so it's trailing behind the other numbers.

 

[derek420colorado]

Whoa lol

 

[Mizzo81]

What’s your water source. When I used to mix with my well water my ph would start rising after 12 hrs is my guess. Once I started using RO water my ph stays stable.

 

[karlkutta]

Fair enough about the water. I actually use tap water that I leave sitting for 24hrs + however long until i actually use it.
I had measured the ph at 7 and just checked again, it still is at the same point so that is pretty stable.

I also have some Roots Organic HPK that I will add to the original post, this stuff started off with a lower Ph than what the water was but then came back up after 24hrs and is sitting at the perfect range i think.

 

[Mañ'O'Green]

If you aerate your water for 48 hours prior to mixing it will help with the PH stability. Aeration will precipitate some of the calcium carbonate that falls out of solution over time. This is the most common cause for a PH shift in mixed nutrients not in a reservoir with roots.

 

[karlkutta]

If you aerate your water for 48 hours prior to mixing it will help with the PH stability. Aeration will precipitate some of the calcium carbonate that falls out of solution over time. This is the most common cause for a PH shift in mixed nutrients not in a reservoir with roots.

I will try that out, I have an extra airpump laying around. Do you think that leaving the water sitting for X amount of time would achieve the same result? asking since I usually have a gallon or two that sit for a week i would say.

 

[Mañ'O'Green]

I will try that out, I have an extra airpump laying around. Do you think that leaving the water sitting for X amount of time would achieve the same result? asking since I usually have a gallon or two that sit for a week i would say.

It might but aeration is the way to go.

 

[Little Brother]

i've heard that water ph can fall from leaving it out in the air. the carbon in the air binds with something in the water to form some kind of acid. i'm not sure how drastic the change is though. probably pretty minor

 

[karlkutta]

my water seems quite stable, I have several jugs ready at a time and from 1 - 7 days they all are in the same ph
I will try the aeration though.