Because I was getting frustrated with the lack of results from countless water changes trying to wash 110 pounds of sand, I looked for a better method. Remembering that
CO2 reacts with calcium carbonate to form soluble bicarbonate, I tried a little experiment with adding
CO2 to dissolve the colloidial calcium carbonate that makes the water so cloudy, this is what I found:
First I tried using sparkling water (carbonated water) since I had an unused 2 liter bottle of it. I grabbed two glasses of the cloudy wash water. To the glass on the right, I added about 1/3 cup sparkling water. To compensate for dilution, I added 1/3 cup regular tap water to the glass on the left. As you can see, the sparkling water did a remarkable job of clearing up the cloudiness:
Unfortunately, I didn't take a picture of the 29 gallon tank before adding the rest of the sparkling water to it, but it also drastically reduced the cloudiness. I didn't have quite enough sparkling water to finish the job, so I went to the grocery store and got a couple pounds of dry ice (frozen carbon dioxide gas). I plopped the dry ice in the tank and waited til it disappeared, just as I'd hoped, the water got super clear!! This really saved a lot of time and effort and frustration.
Added dry ice, you can see the cloudiness of the water
After Dry ice:
