Ph Buffering in Reservoir

[PeopleWish]

I have recently switched from well to city water.

My city water has a starting ph of 9.0~ on average and a ppm of 70~

I am using spurr,

For direct addition to 100 liters:
(see this post: https://www.icmag.com/ic/showpost.ph...60&postcount=2)
1. fill reservoir with 95% of the volume of water needed

2. add potassium carbonate for veg, early-flowering and full-flowering. Default amount for RO water is 0.096 g/L (make sure to pre-dissolve it in some water, then pour it into the reservoir)

3. add potassium silicate, as AgSil 16H it's 0.324 g/L for veg, 0.405 g/L for preflowering and then some ('early-flowering' stage), and 0.356 g/L for later-flowering.

4. add citric acid at 0.024 g/L for veg, early-flowering and full-flowering. If the pH isn't 7.0, then add more until it is 7.0 (make sure to pre-dissolve it in some water, then pour it into the reservoir).

5. add 0.081 mL/L sulfuric acid (35% purity) for veg, 0.081 mL/L sulfuric acid (35% purity) for early-flowering, and 0.058 mL/L phosphoric acid (75% purity) for full-flowering (no sulfuric acid at that stage).

6. check pH and adjust if it's above ~6.3, use citric acid.
add fertilizer compounds (by weight) according to screenshots on page 1 (post #2).

7. start by adding calcium and magnesium rich compounds such as YaraLiva CalciNit and Epsom salt and magnesium nirate.

8. then add micro nutrient metals, such as FeDTPA, zinc, manganese, etc.

9. finally add fertilizer compounds rich in K and P. (the goal is to limit formation of P-Ca, P-Mg, etc., via citric acid affect the cations before P is added).

10. check pH and adjust if needed

11. add the remaining 5% volume of water

12. done.

My res temps are 68-70

It is always agitated, but after 24 hours the ph goes from 5.5 to 6.5 or higher, after 36 hrs is like 7.5.

This is not chill, anyone got any ideas?


Bless

 

[SeaMaiden]

I have recently switched from well to city water.

My city water has a starting ph of 9.0~ on average and a ppm of 70~

Double check the pH value, that doesn't sound right at all. Very low ppm (EC) coupled with exceedingly high pH..? Something isn't right. Usually, with municipal supplied water, you're going to see pH in the 7-8 range, sometimes a wee bit above 8 but not often.

I am using spurr,




My res temps are 68-70

It is always agitated, but after 24 hours the ph goes from 5.5 to 6.5 or higher, after 36 hrs is like 7.5.

This is not chill, anyone got any ideas?


Bless

I think you're battling alkalinity, but I can't really comment on much given the values you've provided. Alkalinity is defined as resistance to pH shift. You can either filter the water, or use sufficient acid to neutralize the carbonates or bicarbonates that are keeping the pH shifted upward. That's more a guess, though, because that low EC/ppm value you provided isn't making a whole lot of sense in my head. But I say take a small volume of water, try pHing it down to around 4-4.5, wait the period of time and see whether or not it bounces. Be sure to report back!

 

[Kcar]

That seems awfully complicated. Though I do something of the same.
Add RO
Add AGSil16h if your using it. This will make your PH shoot up. PH it back down to 6-7
Add main nutes
Add any sulfurs (Epsom, potassium sulfate, etc)
Add your calcium last.
PH again.

Dilute everything! Less chance of minerals bonding together.
Done.

 

[PeopleWish]

I think you're battling alkalinity, but I can't really comment on much given the values you've provided. Alkalinity is defined as resistance to pH shift. You can either filter the water, or use sufficient acid to neutralize the carbonates or bicarbonates that are keeping the pH shifted upward. That's more a guess, though, because that low EC/ppm value you provided isn't making a whole lot of sense in my head. But I say take a small volume of water, try pHing it down to around 4-4.5, wait the period of time and see whether or not it bounces. Be sure to report back!

Thank you for your insight.

My water is already being filtered and i think what is happening is that i am creating "dead water" which essentially has no buffering capability.

Perhaps the answer lies in using just declorinated tape water with a ppm of 300~ as my base and proceed with my base/acid balance.

And I will keep you posted!!

 

[PeopleWish]

double post

 

[Dorky]

Thank you for your insight.

My water is already being filtered and i think what is happening is that i am creating "dead water" which essentially has no buffering capability.

Perhaps the answer lies in using just declorinated tape water with a ppm of 300~ as my base and proceed with my base/acid balance.

And I will keep you posted!!

Just use 1 part filtered tap to 2 parts RO. Makes life easy.

 

[SeaMaiden]

Thank you for your insight.

My water is already being filtered and i think what is happening is that i am creating "dead water" which essentially has no buffering capability.

Perhaps the answer lies in using just declorinated tape water with a ppm of 300~ as my base and proceed with my base/acid balance.

And I will keep you posted!!

I missed this response. I suggest mixing tap with the filtered water, just as Dorky suggests above.

 

[dalilguy]

I have the same "issue" with my city tap. Ph is 9.1 but ec is .4 200ppm 50 of which is Cl I use to ph to 5.5-5.6 and will find my tanks at 6.4+ the next day. I would then ph back down to 5.7 and it will not go above 6.0 anymore.. A day a month etc.. Now I Ph the tank to 5.3 and I make sure I have atleast a couple hours before the next feed and my tank won't pass 6.0. This happens to me regardless of the base I'm using. None hold the ph steady the first time.

I'm in coco so this ph swing is fine for me.

 

[Hydro-Soil]

Hrmm... I don't get it.

Are you using R/O water or not? If you are, what's the pH of it? (just drop a pinch of nutes in a gallon and test... it'll be just slightly lower than the reading on your meter. Drops you can just test it plain)

If you're not... why aren't you? pH of 9 out of the tap? Get an R/O and filter it... problem solved.

People underestimate the power of being able to pick up and move nearly anywhere... and not have to change the way they use their nutrients. An R/O machine can do this for you. There are a lot of threads on here about growers that moved and had extreme difficulties adapting to their new water source. Tap water and well water can (and often do) change their contents as the seasons change.

Stay Safe!

 

[PeopleWish]

I do filter my r/o. Essentially I am stripping out all alkalinity and creating a phenomena known as "dead water". I have the capability to double or even triple R/O my water at 80+psi and threw large membranes but that would be useless here and would result me with a ppm of like <1 and "deader" water.

This cities water has an average 9.3ph tap H20 which is pretty normal (9.0 is standard )
and an average of 144ppm of CaCO3 which is also fairly normal for this and surrounding municipalities.

I said I used Spurr and spurrs formulations assume the use of R/O. Im not a rookie bro.

Anyways, I figured out my problem with balancing my bases with my acids. By stripping the majority of alkalinity and then rebuffering with an appropriate ratio of carbonates:acids (slightly diff that spurr) and a 50/50 RO:Tap base I have been able to achieve a stable rez ph at 68F starting at 5.5 4 days ago and now it is only 5.8 and holding strong and I expect it to hold atleast another 3 days. At another location I have been able to buffer a 500gallon res for a few weeks with out the need for a ph doser.

I think its funny that you just assume that a single run through a membrane solves reservoir buffering issues, someone with 6k+ posts should probably be a tad bit more informative--not being malicious or anything. Like the subject is linear or something, like R/O is the definitive answer.

And I dont have hard times adapting, my plants are fucking crushing, its just I had to mix like 15 barrels every single day, now its once a week.

 

[Hydro-Soil]

I think its funny that you just assume that a single run through a membrane solves reservoir buffering issues, someone with 6k+ posts should probably be a tad bit more informative--not being malicious or anything. Like the subject is linear or something, like R/O is the definitive answer.

You're right.

All my experience has been with GH nutes and R/O units in some crazy water situations. GH has rock stable pH buffering and has worked exactly the same in every situation.

You're playing with a completely different deck, so yeah... I can see that now.

Stay Safe!

 

[SeaMaiden]

I do filter my r/o. Essentially I am stripping out all alkalinity and creating a phenomena known as "dead water". I have the capability to double or even triple R/O my water at 80+psi and threw large membranes but that would be useless here and would result me with a ppm of like <1 and "deader" water.

This cities water has an average 9.3ph tap H20 which is pretty normal (9.0 is standard )
and an average of 144ppm of CaCO3 which is also fairly normal for this and surrounding municipalities.

Jesus Jumping Christ, a pH of 9 is standard where you are?? Just throw in some gravel and sand and you'd have concrete. I thought the water at 8.5 was bad!

I said I used Spurr and spurrs formulations assume the use of R/O. Im not a rookie bro.

Anyways, I figured out my problem with balancing my bases with my acids. By stripping the majority of alkalinity and then rebuffering with an appropriate ratio of carbonates:acids (slightly diff that spurr) and a 50/50 RO:Tap base I have been able to achieve a stable rez ph at 68F starting at 5.5 4 days ago and now it is only 5.8 and holding strong and I expect it to hold atleast another 3 days. At another location I have been able to buffer a 500gallon res for a few weeks with out the need for a ph doser.

Excellent to read. Have you sorted out the precise carbonate:acid ratio, and how did you finally settle on the method? Another question about your municipal water supply--are "they" (the folks who are providing this supply) fairly consistent in their treatment methods and what they push through the pipes? I ask because I've been reading a few threads this winter on folks who are suddenly having issues, only to find out that the source water has changed for one reason or another.

 

[dizzlekush]

I have recently switched from well to city water.

My city water has a starting ph of 9.0~ on average and a ppm of 70~

I am using spurr,




My res temps are 68-70

It is always agitated, but after 24 hours the ph goes from 5.5 to 6.5 or higher, after 36 hrs is like 7.5.

This is not chill, anyone got any ideas?


Bless

First off Spurr's formulations are awesome, but use way too much Si. His formulations call for 80-100ppm, when 5-30ppm is much more likely to be the optimal range for cannabis. The huge amount of silicate in your solution is part of the drastic rise in pH. try taking out ~66% of your potassium silicate, ive tested Si at low levels compared to high and have seen no difference in overall plant health, stem strength, salinity resistance etc, and now im dumping much less alkalinity into my rhizosphere that my roots have to deal with.

The other issue is that your organic acids (citric) are probably being subject to microbial degradation. I suggest replacing your organic acids with inorganic ones (Nitric, Phosphoric, Sulfuric). Usually Chlorine dioxide would be added to prevent microbial activity, but Citric acid reacts with aqueous chlorine and produces carcinogenic and mutagenic chlorine species, some of which have never even been identified by scientists.

Here's spurrs latest notes on his formulas, they're over a year old, so they're dated, but they're the most current modifications he's mentioned.

a.) Reducing ammonium nitrogen concentration by 10-25 ppm in full-flowering stage may be beneficial to some cultivars or strains.

b.) Reducing silicon concentration by 10-25 ppm in all growth stages may be beneficial to some cultivars or strains.

d.) When I accounted for pH increase from potassium silicate and pH decrease from other fertilizer compounds, I underestimated a bit. Thus, if you are using Bru'n Water set the goal pH after addition of citric acid from pH 7.0 to 7.5 or 8. Then increase the UNH AlkCalc goal final pH by the same amount, e.g. from pH 6.0 to pH 6.5 or 6.8. The results should make final working solution (nutrient reservoir) in the goal pH range without affecting the nutrient profile (you will still use the same amount of sulfuric or phosphoric acid). Then, after all fertilizer compounds, acids and base are added and mixed, simply add more citric acid to reduce pH to 6.0 or 5.8 without affecting the nutrient profile. However, the final alkalinity will be less accurate in a tight ppm range, but sufficiently accurate in a wider ppm range. I really is best practice to test your source water and enter that alkalinity and pH into Bru'n Water.