precipitating sodium bicarb?

[christyf5]

Well I guess technically its sodium carbonate since I bake it for an hour to drive off the water.

Anyway, I just found a pretty generous pile of it in the sump. What am I doing wrong? Any suggestions?

TIA :biggrin:

[Stones]

I found I had the same problem when dosing sodium carbonate. No matter how little I dosed in the sump, I would always end up with load of precipitate.

I found that dosing sodium bicarbonate worked much better although it did end up lowering the pH somewhat. Dosing sodium carbonate, I couldn't keep my alk levels above 7 without execessive precipitation. Dosing sodium bicarbonate, I was able to get my alk as high as 12 without any precipitation.

[sphelps]

Are you mixing it with the proper amount of water first, before adding to the tank? Then are you adding it slow enough?

I know something else in the water in needed to create the reaction needed, I'm no chemist so I'm not 100% sure what it is (could be CO2 or hydrogen ions??) but my guess is you don't have enough of it, whatever it is :neutral:

I don't usually dose sodium bicarb but I do often dose calcium hydroxide and if I need to dose a lot I add vinegar as well which not only prevents the PH from spiking but aids in the reaction preventing precipitation.

[christyf5]

I found I had the same problem when dosing sodium carbonate. No matter how little I dosed in the sump, I would always end up with load of precipitate.

I found that dosing sodium bicarbonate worked much better although it did end up lowering the pH somewhat. Dosing sodium carbonate, I couldn't keep my alk levels above 7 without execessive precipitation. Dosing sodium bicarbonate, I was able to get my alk as high as 12 without any precipitation.


oh ok cool thanks for the info! I'll try it :biggrin:

[christyf5]

Are you mixing it with the proper amount of water first, before adding to the tank? Then are you adding it slow enough?

I know something else in the water in needed to create the reaction needed, I'm no chemist so I'm not 100% sure what it is (could be CO2 or hydrogen ions??) but my guess is you don't have enough of it, whatever it is :neutral:


I mix it with FW and my aquatronica doses approx 100ml over the course of 6 hours or so. I thought that would be slow enough but you can see each individual drop precipitate and float down to the bottom of the sump. Hmm, maybe I'll hit RC and see what I can find then.

[sphelps]

Yeah there's a lot a of good articles explaining this kind of reaction, I remember reading it but can't recall the exact formula.

[christyf5]

found one: http://www.reefkeeping.com/issues/2005-07/rhf/index.php#5

I gotta go put that in the library :razz: