Citric acid is a weak acid found in fruits such as lemons and oranges. Like other acids, citric acid can help you remove stains and rust deposits from toilet bowls without causing any damage to the porcelain surface. Citric acid contains just enough acidic concentration to get the job done without etching or damaging household surfaces in any way. It doesn’t harm the environment. Citric acid (due to its oxidizing properties) removes rust with greater ease than some commercial products. It is a natural material (found in fruit), and is non-toxic. http://www.assignmentexpert.com/free-questions/question-on-chemistry-other-33159.html
Ethanoic acid is non-toxic and is a weak acid, meaning it will not do any damage to most surfaces as it does not corrode or bind to other metals, therefore can be easily removed through washing or rinsing it.
Ethanoic Acid is the slowest de-scaler of the three acids, and is therefore the least effective. It also may cause an unpleasant smell, and can have a negative effect on the taste of coffee meaning one would need to spend longer time rinsing and cleaning the machine thoroughly to ensure that the taste of the coffee is not affected.
Citric acid leaves behind zero toxic residues and has just enough acidic concentration to descale without etching or damaging household surfaces in any way and there are no volatile compounds or products that harm the environment.
Because citric acid is a weak acid, it won't remove heavy build-up of scale very quickly. It is also a powder hence it must be dissolved for use. It also works best with hot water meaning there will be higher energy consumption. Even when used with hot water, citric acid is not as effective at descaling as Sulfamic acid.
Sulfamic acid is the fastest de-scaler - It dissociates into hydroxonium ions more readily in aqueous solution than the others,