Agree with the above statements - beach sand or playsand is too fine for FW
tanks and may alter your parameters. You could put some sand in a cup of tap water for a few days and then do pH, GH
, and KH
tests on the water in the cup. These test results should still be the same as your tap water tests. If anything changed - for example, the pH rose - then unless this is an African cichlid tank, you would not want your substrate altering your parameters. To do this test accurately, you would also want to do a "control" test on your tap water. Pour a glass of water and let it sit out for 24 hours. Do the pH, GH
, and KH
tests on the tap water. Compare these results with the sand and cup water results. They should be the same. If not, the sand is altering the water parameters.
I just found some pool filter sand. I went around to a few pool supply places last week and asked them for a cup of pool filter sand. I then added the water to it and did my testing. All the pool filter sand that I got was inert; it didn't change the water parameters, but I liked the looks of one over the other, so I'm going to get that one.