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This trial was carried out using distilled water to determine how long the experiment would last without the influence of carbonates (present in tap water). In addition, another parameter that was inadvertently changed was the brand of lime, since the previous supply of lime was almost over depleted. The new lime was of a different brand (having brand had 70% calcium hydroxide compared to the older lime containing 96% Calcium Hydroxide). (Were there other distinguishing factors of the new brand of lime? Maybe a list of chemicals and % composition for each would be helpful especially comparing hydroxides and bicarbonates) Thus during this trial, not only was the effect of water quality but also the effect of lime quality was evaluated. For this trial the pH remained stable at 12 for just 3.5hours.
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For the above trial, the pH remained at 12 for about 3.5 hours but the performance of the apparatus changed drastically. The new lime was much more soluble in water and diminished the number of big and generally was composed of finer particles within the apparatus. The new lime did not accumulate in clusters at the bottom of the apparatus. This gave an almost perfect and uniform suspension of lime throughout the apparatus leaving no scope of observing the particle movements.
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One, that the distilled water made little impact on the working of the lime feeder. Despite the results, is necessary to figure out the reasons. If effectively the distilled water has not eny effect; or if the distilled water used had any impurity.
(Again this could be due to the fact that the distilled water, though stored in a closed plastic container was kept so for more than 3 weeks, which resulted in a leakage of Carbon dioxide through the plastic walls so that in effect the distilled water was no better than tap water after a long duration.) (I disagree that atmospheric carbon dioxide would change the pH of the system since it is already in equilibrium with atmospheric carbon dioxide. I think a more likely explanation is the presence of carbonates on the walls of the plastic container) Second, the decrease in efficiency of the system was due to the fact that a different lime quality of lime was used which and did not match the hypothesis on which the design was based.
Further experiments are needed to probe or reject the distilled water hypothesis. Is necessary to check the performance of the experiment with the first lime brand and distilled water, and with the second lime brand and tap water. Those results will provide comparable parameters. (Make some comments about future experiments here given the results. You have two variables to test for, so which one will you test for first.)