Can I dose alkalinity by pH reading?

FoxyFace · Jan 14, 2019

I run my ato to a kalk stirrer which almost meets my tanks needs. The alk is a bit low, around 7 dKh. I want the alk closer to 9 dKh.

Can I auto dose alk via pH readings? Naturally, this would be an average day. I know extremes of gas exchange can effect what I’d be looking to do.

Thanks!

saltyfilmfolks · Jan 14, 2019

You answered your own question.

No.

JimWelsh · Jan 14, 2019

NO!
https://www.reef2reef.com/threads/using-ph-to-control-alk-dosing.535805/

FoxyFace · Jan 14, 2019

Even as a trending tool? That’s how I would use it.
So are we considering alkalinity more stable than pH?

Martin Kuhn · Jan 14, 2019

You require to measure Ca and Alk together. This informs gives clarity about one of the most important parameters of your reef tank. Calcium Carbonate level.

The ph Level of your tank is something TOTALLY different. It should stay in a OK range automatically, if you respect some very basic rules.

You definitely can’t use pH Value to steer your tanks calciumCarbonate Level (where alkalinity is only one part of)

saltyfilmfolks · Jan 14, 2019

FoxyFace said:
So are we considering alkalinity more stable than pH?

Considering,no. It is.

Frogger · Jan 15, 2019

Martin Kuhn said:
The ph Level of your tank is something TOTALLY different.

Actually it is not totally different and Alkalinity can be calculated from the pH if you have the CO2 level of your tank. Seneye's alkalinity monitor that they are developing will do exactly that.

saltyfilmfolks · Jan 15, 2019

Frogger said:
Actually it is not totally different and Alkalinity can be calculated from the pH if you have the CO2 level of your tank. Seneye's alkalinity monitor that they are developing will do exactly that.

Umm......

JimWelsh said:
NO!
https://www.reef2reef.com/threads/using-ph-to-control-alk-dosing.535805/

JimWelsh · Jan 15, 2019

Frogger said:
Actually it is not totally different and Alkalinity can be calculated from the pH if you have the CO2 level of your tank. Seneye's alkalinity monitor that they are developing will do exactly that.

This has previously been discussed quite a bit. One relevant discussion can be found here. The TL;DR is that you have to know both pH and CO2 levels with considerable accuracy in order for this approach to work, and achieving that with a somewhat limited budget is a non-trivial challenge.

The unknown (and on a practical level, currently unknowable with sufficient accuracy) CO2 level is the constraint here.

FoxyFace · Jan 15, 2019

JimWelsh said:
This has previously been discussed quite a bit. One relevant discussion can be found here. The TL;DR is that you have to know both pH and CO2 levels with considerable accuracy in order for this approach to work, and achieving that with a somewhat limited budget is a non-trivial challenge.

The unknown (and on a practical level, currently unknowable with sufficient accuracy) CO2 level is the constraint here.

My objective was to use pH as a trending tool. I want to put that beautiful graph to work!

I dose daily and was looking to explore options.

However, frags are getting too expensive to wing it!

JimWelsh · Jan 15, 2019

You have to understand that pH "as a trending tool" is "trending" the combination of (primarily) two things: alkalinity and CO2. Then, there are the additional "trending" effects of temperature and salinity, to the degree that they vary. You are not observing the "trend" of just one thing. You are "trending" the combined effects of a bunch of different things. That makes it pretty much useless for the stated purpose.