A couple of people have reported that certain dechlorinators (but not all) can raise the pH - mine doesn't, but it would be interesting to know if this can happen and if so, which brands. If you try leaving some water in a cup overnight and then testing, as minxfishy suggested, it would be interesting to try a second cup with water + dechlorinator.
IME it's not a good idea to try adjusting with chemicals like pH Minus, especially if your water is hard - they don't seem to work long-term and you just risk pH fluctuations which will harm your fish a lot more than a stable high pH.