I recently bought a salifert test kit because my old red sea test kit would give me inconsistent results, I did a spin test on my water box at my lfs, I got 8.2 alk. When I tested it myself after coming back my salifert I got 8-8.3 alk (tested 2 times). That was on the 18th, today I tested my alk and got around 6 twice. Is this a testing kit error or is it possible it dropped that much.