Municipal water KH and pH fluctations during CO2 injection: a newbie question

[propsi]

Hi,
My first post. After a year of reading I'm finally attempting to connect the dots and starting my own tank, so I have newbie questions.

First:
My municipal water comes out at around 100 ppm KH (pH 7.5), which for some (Walstad et. al. ), is considered soft. No GH readings to give. Would I gain any benefit by adding hardening agents to the water after a WC? What I can't gauge is it's actual buffering capacity. I would ultimately like to install a pH controller to regulate my CO2 and I wonder if the pH would fluctuate rapidly during the daytime under these conditions. And if it would, does it matter ? Obviously, and in an ideal world, the controller would prescribe the limits of fluctuation, but nonetheless...

Second:
I'm thinking of controlling CO2 using Neptune's Apex jr controller fitted w. ph probe etc. . Has anybody used this combination ? Is it feasible? I'm considering this controller because I would eventually like it to control dosing. Any thoughts ?

with Thanks,
V.

 

[Biollante]

It Is a Conspiracy, a Conspiracy, I Tell You: CaCO3 for GH & KH

Hi V.,

Welcome!:glee:

On your water report general hardness (GH) may be reported as “total hardness” or “permanent hardness.”

General hardness may be reported as Calcium (Ca[SUP]2+[/SUP]) and Magnesium (Mg[SUP]2+[/SUP]), and then you can calculate general hardness as Calcium carbonate:

• [CaCO[SUB]3[/SUB]]= 2.5[Ca[SUP]2+[/SUP]] + 4.1[Mg[SUP]2+[/SUP]]

As for as alkalinity, KH (just to maintain the confusion is also reported as CaCO[SUB]3[/SUB]) is quite nice,

• 100-ppm as CaCO[SUB]3[/SUB] is about 5.6-dKH.

It is important to remember there can be interferences to pH probe readings, for now do not worry about those.

With a pH of 7.5 you are looking for about pH 6.5 to indicate about 30-ppm of CO[SUB]2(aq)[/SUB].

If you have critters, in dialing in your CO[SUB]2(aq)[/SUB], do not exceed an additional pH drop of more than 0.2 per day and even then it is best get to drop the pH over the course of 10 days or so.

• keep an eye on the critters any distress, return to the previous setting

I know it seems odd and no doubt, the sheriff of the internet will want me off for saying this and there will be much howling and lamentation in the land.

• Even though each night the CO[SUB]2(aq)[/SUB] will return to about 3.5-ppm and the pH will return to 7.5, it is still a good idea to adjust the CO[SUB]2(aq)[/SUB], to 30-ppm slowly.

In other words if on the first day you drop the pH to 7.4, then the next day drop it to 7.3 and so on until you reach pH 6.5. At this point, leave the system alone for at least a week before any more tweaking.

Good luck,
Biollante

 

[propsi]

Thanks for the equation, and thanks for chiming in. Good tips. I have a base point I can work on.

with thanks,
v.