Citric acid solution pH and alternatives

[carri10]

I currently use, like many of you, a high concentration citric acid solution to clean my Reef equipment. My understanding is that the pH is around 2 to 2.5 at the concentrations of citric acid I use, around 30 to 40%.

Looking to reduce the amount of chemicals I hold, is there anything special about the citric acid that means that I cannot replace by an equivalent pH solution provided by HCL, also known as muriatic acid?
Does the high concentration of citric acid somehow buffer the pH at that lower level and therefore provide a longer lasting solution?

Any reasons why I couldn’t just use an equivalent pH concentration of HCL?

As a subsequent question, how low can I go in pH before I start to damage the equipment?


Thanks.

 

[Randy Holmes-Farley Verified Community Expert]

Assuming the equipment is plastic, or ceramic, like a powerhead, a pH of 0 (1 N HCL) is fine. That’s about a ten fold dilution of muriatic acid.

pH largely determines the rate of calcium carbonate dissolution, but just fyi, pH 2.5 citric acid will last longer because it is buffered against a pH rise while HCl is not.

I often use HCL for cleaning.

 

[carri10]

Assuming the equipment is plastic, or ceramic, like a powerhead, a pH of 0 (1 N HCL) is fine. That’s about a ten fold dilution of muriatic acid.

pH largely determines the rate of calcium carbonate dissolution, but just fyi, pH 2.5 citric acid will last longer because it is buffered against a pH rise while HCl is not.

I often use HCL for cleaning.

Thanks. It was the buffering I was alluding to. Wasn’t sure how powerful the effect was.

I’ll go with a 0.1M HCl.
pH of 1 and more economical on my acid stocks.
Simple to knock up quickly as well.

Thanks.