I just googled your water quality report, and put the link below.
The relevant info for your fish doesn't show up until quite away into it, depending on which area you live in. The normal tap pH is @6.6 so your tank hasn't dropped that that far down, but as RD suspected, you are in a fairly low alkalinity (buffering capacity area). So beside lots of water changes, crushed coral or oyster shell in filters or substrate would help buffer your tank water between changes. http://www.pittmeadows.bc.ca/assets...pdfs/Drinking_Water_Quality_Report_-_2014.pdf
I now have two bags of crushed coral in there, and pH has not risen at all!
My ammonia is 0, and so are my nitrites. Nitrates are around 10.
I went and bought a new test kit but that's not it.
Have done two water changes since I started this thread.