NO3:PO4-x and alkalinity

[Colin]

Can anyone chime in on NO3O4-x's effects on alkalinity? It contains acetic acid, and according to this article by Randy Holmes-Farley, acetic acid may contribute to total alkalinity. The article is a little over my head, but it doesn't seem to specific on how much it may contribute.

Thanks,

--Colin

 

[bertoni]

Acetic acid will reduce alkalinity temporarily until bacteria consume it. The equations are here:

http://reefkeeping.com/issues/2005-01/rhf/index.htm#6

The paragraphs are specifically about combining lime and vinegar, but the equations work without the lime.

 

[Colin]

I was looking specifically at this part of the above link:

As an example, consider those people who are dosing limewater with organic acids such as vinegar. Acetic acid is a complication to an alkalinity test that may or may not be significant to people using it, but the more vinegar that is used, the more confounding it may become. Ultimately, the acetate that is added in this fashion will be oxidized into CO2 and OH- (equation 4), with the OH- providing alkalinity in the same fashion that the original limewater would have.

--Colin

 

[bertoni]

When the acetate is consumed, it releases one unit of alkalinity. When the acetate acid molecule was added to the tank, it consumes 1 unit of alkalinity due the the H⁺ released. The net effect is zero. The presence of the acid might confuse an alkalinity test, for various reasons, but that's different from the effect on actual alkalinity.

 

[Colin]

I see. My problem is my alkalinity is reading too high. How might the acetic acid affect an alkalinity test? I'm using a Hanna Checker.

--Colin

 

[reelfreak]

I dose DIY nopox, and trust my hanna checker. I wait a couple hours after its dosed usually,but that's just because of dosing pump timing.
I wouldn't overly sweat it IMO.

 

[JoeBatt]

I dose 0.64 ml of NoPox a day in a 350 litre net tank, and it keeps my N03 at around 0.3 and Po4 at around 0.03. I would find it hard to see how that would increase the alkalinity more than a tiny fraction.

 

[Colin]

I dose 0.64 ml of NoPox a day in a 350 litre net tank, and it keeps my N03 at around 0.3 and Po4 at around 0.03. I would find it hard to see how that would increase the alkalinity more than a tiny fraction.

That is far less than most would dose. Recommended dosing is anywhere from 1 to 3 ml per 100 liters.

 

[bertoni]

The effect of a dose of that size on an alkalinity kit is zero for our purposes. It'll lower the alkalinity a tiny bit until bacteria consume the acid. The more common sources of excess alkalinity are pH buffers and tap water. A bad batch of salt is another possibility.

 

[JoeBatt]

Colin, yes it is a low dose but its what I need to keep the No3 and Po4 at the levels I need. Anymore and I would push the levels to zero and that is no good at all. The recommended dosages are the levels you use to get started then you adjust to need. Its basically similar to the Vodka dosing schedule I used to run, but much more powerful.