Low pH issues

[Ranjib]

Hello,
Its been few weeks since I have added constant pH monitoring in my tank, and what this revealed is that my tank pH is rather low. It hovers between 6.3 to 7.6 , with a daily peak around afternoon and low at late night. I am using atlas scientific pH probe with 3 point calibration (4,6 and 10).

I have a small tank, 29G biocube, with skimmer in it, no refugium and relatively low bioload (only three fish). Its a mixed reef with sps and some lps and zoas. My sps are doing ok, they are not dying off, they are growing slowly. My softies and lps are thriving. My tank is 2.4 years old.
I'll be doing a titration based test as well to confirm the results , as @SDchris suggested. I am also going through the pH related articles mentioned in this forum (@Randy Holmes-Farley some of the links are broken :-( )

Any suggestions?

 

[themcfreak]

Easy, quick fix for most people (myself included) is to run your skimmer intake tube to draw air from outside. Either crack a window as small as it can go (you could insulate the crack with a small insulation strip from Home Depot/Lowe's) and run the tube out of the window, or make a more permanent hole and seal. Inside typically has elevated CO2 which can bring pH down. Air from outside does this to a much lower extent.

Much more expensive option: CO2 scrubber. Either way, those are quick ways to make a potential raise in pH.

 

[Ranjib]

My tank is located at a place that I dont think will be easy to draw air from outside. I am mixing kalkwasser in my ATO starting this week, and hoping that will make a difference.

 

[Randy Holmes-Farley Verified Community Expert]

Something is wrong with the measurement. There's no chance whatsoever that a reef tank has a pH of 6.3.

What pH meter do you have?

What brand calibration buffer with a pH of 6?

 

[Ranjib]

Something is wrong with the measurement. There's no chance whatsoever that a reef tank has a pH of 6.3.

What pH meter do you have?

What brand calibration buffer with a pH of 6?

I am using AtlasScientific pH probe and the calibration solution that comes with it (ph 4, 7 and 10).

 

[Ranjib]

Ok, I am revisiting this as I have learned a lot since I reported this, and I think others would find it useful,
After @Randy Holmes-Farley pointed out this can not be correct, I went read some of his prior write ups and also some technical documentation about pH probes. I was not using a voltage isolator along with the pH sensor circuit, without this the sensor reading are prone to aberrations from stray voltage, from tank or from controller's internal circuit. I didn't panic after the initial findings as my corals were OK and there was ample advice in this forum to not chase pH without understanding whats going on.

Couple of days before I have added the recommended voltage isolator in pH sensor circuit and that address this issue. There were two noticeable difference, first, my tank pH suddenly jumped by 1, earlier it used to vary from 6.6 to 7.7 and now it varies from 7.6 to 8.2 . Second , the ph readings do not show a jittery curve any more, they are smooth contiguous readings. Here is a chart showing the changes from past two days

I have orderd a separate pH testing kit as well, to validate the readings independently. But I think I have dialed it now. #reefpi