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One potential set-up for a smaller scale experiment would be to put several shorter vertical columns in series, connected by flexible tubing, and end with one final diagonal tube settler column. This is an experiment that could easily fit on the bench top and would be easier to control and run. Figure 1 shows a possible set up for this experiment: 
Figure 1
Potential experimental set up in which the vertical column is broken up into multiple, shorter columns followed by one final diagonal tube settler.
2. Continue to run controlled experiments with both distilled water and tap water in order to characterize the effect that carbonate ions have on the reactor's performance. Our work from this semester did not yield results from which we can confidently draw conclusions about the importance of this effect.
3. Try the Honduran lime to see if there's any significant difference.
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6. Explore entirely alternative methods of feeding lime or otherwise adding alkalinity to the plant flow. A possible new design is considered by the team.
7. Consider temperature as a variable in future experiments, keeping in mind that CaCO3 is less soluble when hot.
8. Possibly experiment using a different base, such as Sodium Bicarbonate.