Cant keep up with my Alkalinity needs - help

[Randy Holmes-Farley Verified Community Expert]

Umm I'm fairly certain your backwards. Its the drop in PH causes the carbonate to transistion to bicarbonate.

That is certainly true. It has no impact on alkalinity if it is caused by CO2, but it does convert a carbonate into a bicarbonate. If it was caused by CO2, that CO2 became a bicarbonate. hence you have:

CO2 + CO3-- --> 2 HCO3-

Both sides have the same alkalinity.

 

[GARRIGA]

Could create a simplified calcium reactor by using coral skeletons as biological media. That’s what I’m experimenting with and I can’t keep my alkalinity down. Keeps rising from 9 to 14 until I take action to reduce it.

Concept based on nitrification acidifying the water which melts the skeletons thereby releasing calcium and alkalinity similar to a calcium reactor without artificially adding CO2. In addition I have denitrification occurring which is replacing the alkalinity lost during nitrification.

Test tank and yet to add corals so don’t know how much this will help once a consumer of alkalinity is added and probably something I should do soon. Been trying to establish coralline algae to be that consumer but that’s still a work in progress. Do expect this will reduce my need to dose alkalinity and calcium. This test has shown me that.

 

[Randy Holmes-Farley Verified Community Expert]

PH and Alk are linear. So if PH drops alk Drops. That's why it's almost impossible to have PH below 7.8

That assertion is incorrect.

The pH inside of a CaCO3/CO2 reactor before encountering media is well below pH 7.8 due tot eh added CO2, and has not changed in alkalinity.

it just takes more CO2 to lower the pH more.

 

[Donavon]

Thanks for everyone that chimed in here, I have a lot of reading to do tonight.
Already I have a better understanding of the chemistry
I will start with increasing my dosing over the next week or so, to see where that leads.
Thanks again!!

 

[Lavey29]

I'm not sure I follow how low pH would lead to unstable alkalinity.

What problems does low PH or high PH cause for a tank?

 

[Lavey29]

Is it?

Seems like a very complex question to me, if you want to understand the ways and degrees of impact, but there are many interrelationships between alk and pH in a reef tank.

That said, one should not insinuate that IF the pH changes, that alk must change. That is not true.

One can take seawater and add or remove CO2 by aeration, and that process alone changes pH but not alkalinity.

Hence the part directly or indirectly. If PH is not an important component in the reef system then why do you go in to so much research and detail about its cause and affects? Isn't there some nexus between all the major components in a reef system along with minor ones as well?

Note: I have complete respect for your knowledge in these areas.

 

[Randy Holmes-Farley Verified Community Expert]

What problems does low PH or high PH cause for a tank?

low pH stresses calcifying organisms, and below pH 7.7, coral skeletons can begin to dissolve.

The first apparent risk to high pH is excessive precipitation of calcium carbonate on heaters, pumps, sand, etc.

 

[Lavey29]

low pH stresses calcifying organisms, and below pH 7.7, coral skeletons can begin to dissolve.

The first apparent risk to high pH is excessive precipitation of calcium carbonate on heaters, pumps, sand, etc.

And will either of these situations directly or indirectly affect alk, cal or mag?

 

[Randy Holmes-Farley Verified Community Expert]

And will either of these situations directly or indirectly affect alk, cal or mag?

Yes. Even evaporation of tank water water will impact alkalinity. Nearly everything in a reef could somehow impact alkalinity.

But in the context of the problem claimed by the OP of not being able to maintain alkalinity, low pH is not one of the possible causes.

I'd suggest it's time to move on from a purely semantic debate.

 

[Lavey29]

Yes. Even evaporation of tank water water will impact alkalinity. Nearly everything in a reef could somehow impact alkalinity.

But in the context of the problem claimed by the OP of not being able to maintain alkalinity, low pH is not one of the possible causes.

I'd suggest it's time to move on from a purely semantic debate.

Thank you

 

[ApoIsland]

Thanks for the help, I was afraid to do too much at a time. And I had not really done the math correctly.

Did you try doubling up the dosage today to see if that made a difference?

 

[Donavon]

Did you try doubling up the dosage today to see if that made a difference?

Last night I increased the dose by 10 mil per hour not double. A marked difference was seen today, nearly ~20 hours later.
My Alk reading was right at 7 I will see if it comes up a point or two tomorrow. If it hasn’t gone above 7 tomorrow I will increase again