Sulfur Denitrator in a low alkalinity environment?

[holdyourlight]

Hi Randy/all-

I'm thinking about setting up a sulfur denitrator in my fish only tank to combat high nitrates. I do not monitor alk in this tank and water changes are very infrequent. I read that a sulfur denitrator will consume alk. Does that mean it will not work properly if alk is depleted? I don't want to have to dose alk in this tank. Thanks for the help

 

[Randy Holmes-Farley Verified Community Expert]

It will work fine, but you’ll want to add buffer periodically and I’d use an alk test to know how much to add. The pH will drop too low otherwise.

 

[holdyourlight]

It will work fine, but you’ll want to add buffer periodically and I’d use an alk test to know how much to add. The pH will drop too low otherwise.

Sorry @Randy Holmes-Farley just now getting ready to do this and wanted to see if you could clarify your comment. Would it be sodium carbonate that i need to add so that the pH doesn't drop too low? Could i not use a pH probe to determine when it needs to be added then i guess an alk test to determine how much?

 

[Randy Holmes-Farley Verified Community Expert]

Sorry @Randy Holmes-Farley just now getting ready to do this and wanted to see if you could clarify your comment. Would it be sodium carbonate that i need to add so that the pH doesn't drop too low? Could i not use a pH probe to determine when it needs to be added then i guess an alk test to determine how much?

You could replace the alkalinity with sodium carbonate or sodium hydroxide. The hydroxide gives about twice the effect.

You can replace alkalinity with bicarbonate also, but it won't boost pH. It will have a small drop.

I'm not sure what pH reading you'd use to know you need alkalinity. In a given unchanging situation, you might figure it out, but then if the room CO2 level changed and pH changed at fixed alkalinity, it is not longer linked to alkalinity in the same way it was originally.