Ph 7.4-7.6 a worry

[arking_mark]

Hi
I have a theory on my low ph.
Could it be caused by my well water having high amount of CO2?
I have read that with well water high CO2 will cause di resin to be used quicker and that would be my rodi system I have used my DI resin faster.
If it is high CO2 could running an air stone in my rodi water for water changes help?
I did notice from the graphs on my apex that Sunday nights after a water change Sunday morning is when it bottoms out. Last week by Wednesday it was up to 7.95 tonight down to 7.5.
What do you think?
Joe

I believe the pH of RODI water should be 7. As it's exposed to the air, it will find an equilibrium with concentration in that air.

When you 1st mix your ASW, it should hit a pH targeted by the salt manufacturer. Most look to hit a pH of 8.3ish. As that gets exposed to the air, it will also find an equilibrium. Since house air is usually higher in CO2, the pH of ASW will naturally drop. If you aerated it will higher CO2 house air, it will find that equilibrium faster.

Your overnight drop seems quite high to me. Options:
1. Refugium on reverse lighting schedule
2. High-ph Alk dosing at night
3. CO2 scrubber with Skimmer

 

[Randy Holmes-Farley]

Hi
I have a theory on my low ph.
Could it be caused by my well water having high amount of CO2?
I have read that with well water high CO2 will cause di resin to be used quicker and that would be my rodi system I have used my DI resin faster.
If it is high CO2 could running an air stone in my rodi water for water changes help?
I did notice from the graphs on my apex that Sunday nights after a water change Sunday morning is when it bottoms out. Last week by Wednesday it was up to 7.95 tonight down to 7.5.
What do you think?
Joe

High CO2 depletes DI resins rapidly, but does not impact the tank wat all unless the DI is depleted. Some folks do aerate their well water prior to the RO/DI to remove CO2 and extend the DI lifetime.

Even then, pH is driven mostly by CO2 in the air at your home, and the alkalinity.

 

[jopo4343]

I tested ph of my rodi water ran right into the test tube
It is 6.5
Will mix up some saltwater tonight and check it. Using red sea blue bucket

 

[Rmckoy]

High CO2 depletes DI resins rapidly, but does not impact the tank wat all unless the DI is depleted. Some folks do aerate their well water prior to the RO/DI to remove CO2 and extend the DI lifetime.

Even then, pH is driven mostly by CO2 in the air at your home, and the alkalinity.

How would you aerate water going into the rodi unit ?

I questioned my lfs why I am burning through di resin so fast .
being on municipal water , I’m assuming the di resin removes chemicals such as chlorine .
supposedly , they add more chemicals to clean the excess run off water

does this make sense ?

even in well water .
the tds would be a lot higher of water levels are higher ?

 

[Smarkow]

How would you aerate water going into the rodi unit ?

Also wondering this! Seems like it would be complicated to manage the pressure and avoid gas bubbles in the RODI unit... hmm

 

[Smarkow]

Not yet mentioned (unless I missed it, sorry)

House plants by the tank
Target a (slightly) higher alkalinity
CO2 scrubber with your skimmer (here’s mine, ignore the inadequate skimmer cleaning, just got back from out of town)

It was a simple project with some Y fittings, tubing, hot glue gun for seal, and of course CO2 absorber canister and media. Don’t forget to hook your skimmer up to a pH probe (replaced regularly and reliably calibrated!)

 

[Randy Holmes-Farley]

I tested ph of my rodi water ran right into the test tube
It is 6.5
Will mix up some saltwater tonight and check it. Using red sea blue bucket

You cannot accurately measure the pH of Ro/DI water, but the value of pH for pure fresh water equilibrated with normal air is below 6.

 

[Randy Holmes-Farley]

Not yet mentioned (unless I missed it, sorry)

House plants by the tank

That part won't be detectably helpful. They absorb too little unless the tank is in a greenhouse type of setting.

 

[Randy Holmes-Farley]

Also wondering this! Seems like it would be complicated to manage the pressure and avoid gas bubbles in the RODI unit... hmm

Folks put it in a large brute type can, aerate, then need a booster pump to send it to the RO unit. It is not a "try it" endeavor. It's a :"determine CO2 is a big issue" first, then do it.

 

[Biologic]

Not claiming to be an expert on pH probes, but you have to be methodical when calibrating and using these. I spent an hour recalibrating my pH probe thinking it might be off to find that it was right on the money. I wish just did a test at 7, 8, 10.

Also, specifically the Apex probes need time to settle when calibrating and when taking a measurement.

I think there needs to be a good sticky on pH probes.

@Randy Holmes-Farley I know borax can be used as a way to check pH probes, but are there any DIY standard solutions one could make at a pH 8.0~9.0?

 

[Randy Holmes-Farley]

Not claiming to be an expert on pH probes, but you have to be methodical when calibrating and using these. I spent an hour recalibrating my pH probe thinking it might be off to find that it was right on the money. I wish just did a test at 7, 8, 10.

Also, specifically the Apex probes need time to settle when calibrating and when taking a measurement.

I think there needs to be a good sticky on pH probes.

@Randy Holmes-Farley I know borax can be used as a way to check pH probes, but are there any DIY standard solutions one could make at a pH 8.0~9.0?

DIY is a relative term, but you can buy or make pH 8 and 9 buffers (I used them).

here's a recipe that can give a pH 8.0 buffer:

Buffer Reference Center

Choose a buffer based on your pH requirements as well as the pKa, a measure of acid strength that accounts for pH, concentration, and temperature.

www.sigmaaldrich.com

Phosphate Buffer Preparation Table – 0.2 M solution ​

Potassium Phosphate Monobasic Anhydrous g/L : 1.27 g​

Sodium Phosphate Dibasic Heptahydrate g/L: 50.81 g

​

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[JrlGravity]

Im not sure if it affects the reading but when calibrating are you calibrating with ph 4 and 7 or with 7 and 10?

 

[Biologic]

Im not sure if it affects the reading but when calibrating are you calibrating with ph 4 and 7 or with 7 and 10?

you should be calibrating to the solution you are trying to measure. Calcium reactor is around ~6.5 , so 4 to 7 calibration. So with 7 to 10 calibration, to measure natural sea water pH around 8.2

 

[Randy Holmes-Farley]

I discuss the relative pros and cons of 4/7 calibration vs 7/10 calibration here:

Aquarium Chemistry: Measuring pH with a Meter

This article describes how pH meters work, how to select one to use, and how to best use it to measure the pH of a reef aquarium.

reefs.com

FWIW, if you use a pH 10 calibration fluid, it is important it not be old as they drop in pH over time as CO2 enters, while pH 7 and 4 solutions usually are more stable.