Before proceeding any further, v/e shall tell first how to determine the A.C.C. 



In table 1, we find the A.C.C. in like proportions to the bicarbonate-carbon dioxide 

 content or the calcium bicarbonate-content. As a matter of fact, and for all practical 

 purposes, the A.£.£. expresses the prevailinK calcium content of a water . It is quite true 

 that small amounts of carbonate magnesium salts (also of sodium and of potassium salts), of 

 humic acid and of silicic acid and of phosphoric acid compounds of alkaline earths, and of 

 alkaline metals have a part in the A.C.C, but one can neglect them in practice. Through 

 titration with hydrochloric acid, one may easily determine their anounts. Only in cases of 

 a very low A.C.C. will they play a more significant role. 



It can be regarded as an unwarrented, purely theoretical exaggeration when for these 

 reasons the A.C.C. is disregarded as an unreliable measure for the calcium rate. 



The estimation of the A.C.C. is based upon the elimination of carbon dioxide from the 

 calciuia bicarbonate by adding strong mineral acids (hydrochloric acid by agreement) to the 

 water and through this process bring about the formation of calcium chloride. 



To a certain amount of water (100 cc), one adds hydrochloric acid until the water 

 becomes acid and the jffl rate drops belov; 4.^, (when freed carbon dioxide does not influence 

 the pH rate any longer). This is seen by the color change of methyl-orange, previoualy 

 added to it. 



The expressions "alkality^' and "alkalinity", formerly in use for A.C.C. are misleading 

 and should be avoided, since one may mistake them for the natural reaction of the pH rate. 

 Still, they are made use of, occasionally, even in the written opinions of experts. 



Identical with A.C.C. are the terms titration alkality. alkaline reserve, basic surplu 

 and also — ^by dividing vdth 3.8 — the term carbonate hardness . 



For A.C.C. tests one needs: 



1. A graduated glass of 100 cc. 



2. A drip bottle with l/lO normal hydrochloric acid. 



3. A drip bottle with methyl-orange. 



4. VTide mouth titrating flask, 200 cc. capacity. 



Fill the titrating flask -vdth 100 cc of water and add 3 to 5 drops of methyl-orange. 

 The v/ater takes on a yellow color. Now add— drop by drop — hydrochloric acid until the 

 water turns orange-red. The number of drops, carefully counted indicates the rate of A.C.C 



A more accurate titration apparatus for special use by fishbreeders was designed by 

 Czensny and may be had with directions from £. Altmann . It consists of a burette with a 

 pinch cock graded at l/lO cc. It shows the consimption of l/lO normal hydrochloric acid 

 per 100 CO of pond water in cc, i.e. the hydrochloric acid combined as cc of N/1 HCl per 

 liter of water. (15 drops equal about 1 cc but this should always be checked in cases of 

 a requested expert opinion.) 



An A.C.C. of 1 corresponds to 2.5 degrees of "Gennan" hardness or 28 milligrams CaO 

 per liter. 



Every progressive fishbreeder should be able to make his own A.C.C. tests. Tlie con- 

 tinuoiM checking of the A.C.C. — especially in calcium-poor regions — is indispensible for a 

 progressive fishery. The proper estimate of the A.C.C. is equivalent to a proper estimate 

 of varying calcium content. 



From the above findings, we can deduce that a very lov/ A.C.C. exposes a pond to a 

 sudden "turning sour" of its water. At the same time, a very low A.C.C, even a medium one 

 of from 1 to 2 causes a very low supply of "corresponding" free carbon dioxide (see table 7 

 so that one observes frequent changes in the pH rate and a relative lack of carbon dioxide. 

 This, of course, lowers the productivity of a pond; it becomes oligotrophic, i.e. food-poor 

 aa £. Schiemenz has shown long ago. 



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