I've noticed a quick search of procedures for cleaning sand often devolves into an argument between those that are proponents and those that are opponents of the process. Rather than get into that debate, I wanted to include my procedure (below) for how I clean my old/used sand to remove most of the detritus and phosphate. If anyone wants to chime in with their own procedure it might be a nice resource for those who want to see different techniques.
1) Rinse sand with tap water thoroughly to remove detritus. Collect any rubble rock/snail shells. This step is usually done with a garden hose until the water runs "clearish".
2) Add bleach, stir well and leave for an hour or longer. If I fill half a 5 gallon bucket with sand, I add about a quart of bleach.
3) Rinse well with tap water and stir vigorously to remove residual chlorine in between the grains of sand.
4) Add a dechlorinator and stir vigorously for a few minutes. Let sit for 30-60 minutes (or all night, this step isn't time sensitive) then rinse thoroughly with tap water.
4) Add 5% vinegar or diluted muriatic acid and stir well (taking the standard precautions around the use of strong acids ) and let sit 20 minutes or longer depending on concentration.
5) Rinse well with tap water (RO water optional) and stir vigorously.
Optional steps:
After the last rinse, you can spread the sand out or leave it in the bucket to dry out fully to dry out any remaining tap water, chlorine, or acid.
To confirm that you have successfully removed all the acid with the final rinse, you can test the ph of any remaining water (or mix water with the sand to get a sample).
Some Notes:
I have used this procedure successfully many times to clean old sand. Weekly testing of the sand over a four week period shows zero nitrates and between zero and 0.05 phosphate using a range of testing kits. All procedures for cleaning are done outdoors, both for ventilation purposes as well as using a garden hose to easily rinse the sand. Besides the use of the acid, none of the steps are time sensitive. Sometimes I'll leave the sand in bleach overnight or separate the steps every few days depending on my schedule. The use of the acid will remove some of the outer layers of sand which binds the majority of the phosphate. The sand grains will reduce in size (marginally), unless you leave the acid in for prolonged times (or use high concentrations), in which case much more of the sand grains will be dissolved.
1) Rinse sand with tap water thoroughly to remove detritus. Collect any rubble rock/snail shells. This step is usually done with a garden hose until the water runs "clearish".
2) Add bleach, stir well and leave for an hour or longer. If I fill half a 5 gallon bucket with sand, I add about a quart of bleach.
3) Rinse well with tap water and stir vigorously to remove residual chlorine in between the grains of sand.
4) Add a dechlorinator and stir vigorously for a few minutes. Let sit for 30-60 minutes (or all night, this step isn't time sensitive) then rinse thoroughly with tap water.
4) Add 5% vinegar or diluted muriatic acid and stir well (taking the standard precautions around the use of strong acids ) and let sit 20 minutes or longer depending on concentration.
5) Rinse well with tap water (RO water optional) and stir vigorously.
Optional steps:
After the last rinse, you can spread the sand out or leave it in the bucket to dry out fully to dry out any remaining tap water, chlorine, or acid.
To confirm that you have successfully removed all the acid with the final rinse, you can test the ph of any remaining water (or mix water with the sand to get a sample).
Some Notes:
I have used this procedure successfully many times to clean old sand. Weekly testing of the sand over a four week period shows zero nitrates and between zero and 0.05 phosphate using a range of testing kits. All procedures for cleaning are done outdoors, both for ventilation purposes as well as using a garden hose to easily rinse the sand. Besides the use of the acid, none of the steps are time sensitive. Sometimes I'll leave the sand in bleach overnight or separate the steps every few days depending on my schedule. The use of the acid will remove some of the outer layers of sand which binds the majority of the phosphate. The sand grains will reduce in size (marginally), unless you leave the acid in for prolonged times (or use high concentrations), in which case much more of the sand grains will be dissolved.
