Magnesium oxide to increase PH

[lany2008]

Hi everyone，
Joined this hobby for three years now, and suffering PH problem for three years. Recently I found I could use MaO to increase PH and might be better than calcium hydroxide or Kalkwasser, because it doesn’t affect Ca and Alk. The chemical theory as below:

MgO + H2O = =Mg(OH)2

I trued this method and it really worked, so wondering if this will produce any side effects?

I used Kalkwasser before, my tank is small, and it doesn’t work very well, because my tank does not require that much of fresh water.

 

[lazycouch]

have you tried using an air pump before?

 

[lany2008]

have you tried using an air pump before?

Yes, I did, but don’t work.

 

[Randy Holmes-Farley]

Hi everyone，
Joined this hobby for three years now, and suffering PH problem for three years. Recently I found I could use MaO to increase PH and might be better than calcium hydroxide or Kalkwasser, because it doesn’t affect Ca and Alk. The chemical theory as below:

MgO + H2O = =Mg(OH)2

I trued this method and it really worked, so wondering if this will produce any side effects?

I used Kalkwasser before, my tank is small, and it doesn’t work very well, because my tank does not require that much of fresh water.

It raises alkalinity exactly the same as kalkwasser.

The obvious issues are rising magnesium, which limits what you can dose since it is so slowly depleted, and it is very insoluble so you will have to dose solids to the aquarium water.

 

[chipmunkofdoom2]

MgO + H2O = =Mg(OH)2

The hydroxide from this equation behaves exactly like the hydroxide in calcium or sodium hydroxide. From Randy's article on limewater:

OH- + CO2 => HCO3-
OH- + HCO3- => CO3-- + H2O

If you want to manage pH without raising alkalinity, there is no other way but to control CO2 in your tank and/or in your home. Having said that, the pH boost from a DIY two-part with NaOH is very powerful. An additive like this may help significantly if used routinely to supplement your alkalinity.

 

[Randy Holmes-Farley]

To make the point more general, it is not possible to add anything normal to seawater that raises pH that will not also raise alkalinity.

The only way to raise pH and not boost alkalinity is to somehow remove CO2 from the water.

 

[lany2008]

The hydroxide from this equation behaves exactly like the hydroxide in calcium or sodium hydroxide. From Randy's article on limewater:

OH- + CO2 => HCO3-
OH- + HCO3- => CO3-- + H2O

If you want to manage pH without raising alkalinity, there is no other way but to control CO2 in your tank and/or in your home. Having said that, the pH boost from a DIY two-part with NaOH is very powerful. An additive like this may help significantly if used routinely to supplement your alkalinity.

Many thanks！

 

[lany2008]

To make the point more general, it is not possible to add anything normal to seawater that raises pH that will not also raise alkalinity.

The only way to raise pH and not boost alkalinity is to somehow remove CO2 from the water.

Thank you Randy！

 

[Randy Holmes-Farley]

Thank you Randy！

You're welcome.

Happy Reefing