Using pH to control Alk dosing

[Terestron]

I have a reef keeper elite controller and set it up so as it monitors pH it will dose Alkalinity (homemade two part) when the pH drops below 8.2 and shuts off when it hits 8.4. My alkalinity stays between 9-11 dkh when tested.

Is this a proper way of doing it? It seems to work well and it doses about every six hours.

 

[Alfrareef]

I have a reef keeper elite controller and set it up so as it monitors pH it will dose Alkalinity (homemade two part) when the pH drops below 8.2 and shuts off when it hits 8.4. My alkalinity stays between 9-11 dkh when tested.

Is this a proper way of doing it? It seems to work well and it doses about every six hours.

Folllowing...

Just one question; Are sure that “correlation” Ph-KH is straight and direct?
I remember several years ago thinking of doing that but I’ve give up after studying the matter. Unfortunately don’t recall why...

 

[nereefpat]

No, that really isn't the proper way to dose alk.

Alk needs to be dosed based on alk demand, not on pH. You can, for example, have a tank with high pH and low alk, or a tank with low pH and high alk.

 

[JimWelsh]

I have a reef keeper elite controller and set it up so as it monitors pH it will dose Alkalinity (homemade two part) when the pH drops below 8.2 and shuts off when it hits 8.4. My alkalinity stays between 9-11 dkh when tested.

Is this a proper way of doing it? It seems to work well and it doses about every six hours.

NO!!!

 

[Randy Holmes-Farley]

Agreed, bad plan. pH is controlled by alkalinity and CO2 levels. The latter varies from day to day and minute to minute.

 

[Terestron]

That was my point - Alkalinity controls pH. Like I mentioned previously I was watching my alkalinity and it stayed within range when doing so as well as keep the pH in the proper range. Previous posters say it is not a good idea but do not explain why. So why is it if my numbers are good it is bad?

 

[Chad3407]

Alk should stay at a consistent level not fluctuate between 9-11 dkh. That's just asking for trouble. A sudden fluctuation of .2dkh has been known to burn and kill corals .

 

[JimWelsh]

pH is controlled by alkalinity and CO2 levels.

Alkalinity controls pH

Your description seems to be missing something that is present in Randy's. Transient low pH due to high CO2 could cause an alkalinity overdose, for instance.

 

[ckalupa]

Ouch. Seriously on the .2 swing causing issues? Some people dose once a day by hand and can see swings much greater than this. Is that a “coral-specific” phenomenon?

 

[btmedic04]

What's your ph normally without any kind of dosing? are you running a skimmer, refugium or some combination? Generally there's no real need to control ph unless it is low (below 7.8 if im not mistaken) but if you do need to raise your ph, a co2 scrubber on your skimmer or the skimmer air supply line run outside or a refugium are your best bets

 

[Silentreefer]

That was my point - Alkalinity controls pH. Like I mentioned previously I was watching my alkalinity and it stayed within range when doing so as well as keep the pH in the proper range. Previous posters say it is not a good idea but do not explain why. So why is it if my numbers are good it is bad?

1 you dont want alk swings keeping more sensitive live stock.
2 co2 affects your ph which will effect your dosing
3 I see an alk overdose in your future if your tank isnt using it it's not going anywhere until you either take it out or it precipitates
4 generally if dr randy says it's a bad idea I'd listen

 

[Silentreefer]

Your description seems to be missing something that is present in Randy's. Transient low CO2 could cause an alkalinity overdose, for instance.

I think in his method high co2 would cause the overdose because ph will drop and the doser will keep dosing.

I have a reef keeper elite controller and set it up so as it monitors pH it will dose Alkalinity (homemade two part) when the pH drops below 8.2 and shuts off when it hits 8.4. My alkalinity stays between 9-11 dkh when tested.

Is this a proper way of doing it? It seems to work well and it doses about every six hours.

9
If you have a doser just dose it the right way and test. if your only going soft/lps just use kalwasser. If your worried about your ph... stop ph is just a number if it's in a acceptable range your golden. Ph probes need calibrating every couple months and need replacement every so often so I wouldn't depend on something like that to have that much control in your tank. alk swings are bad and this has written all over it

 

[JimWelsh]

I think in his method high co2 would cause the overdose because ph will drop and the doser will keep dosing.

You are correct. I meant low pH due to high CO2. Good catch!