Vancouver, BC Tap water question

[keights]

I'm fishless cycling (fish food, couldn't find proper ammonia to use) and I noticed my PH was quite high. So I did an experiment and discovered the water directly out of the tap has a PH of approximately 6.4 BUT after it sits for a few days it goes to 7.4...after it's been in the aquarium for a few days it goes as high as 8.0 and stays there....water changes take it down to about 7.2 but, within two days, it's back up.
Is this a common problem with our water? What kind of fish can I put in a 10g hex with this type of water?
Thanks!

 

[Notophthalmus]

That's strange. What do you have in the tank? Any gravel or rocks? If so, what kind? It's pretty normal for pH to drop in a tank, but odd for it rise.

 

[keights]

Nothing interesting in the tank that should be causing a change in PH...regular aquarium gravel, resin decoration, silk plant, heater and fiter...that's it. A friend has a pond and her PH is around 7.8 right now (since our tap water comes from dams I have to assume the same problem...but two months ago her ponds PH was 6.2).

 

[Notophthalmus]

Well, it beats me. As far as fish go, most species should be OK, especially if they come from local pet stores and so are used to Vancouver water. If you order them from elsewhere, slowly acclimate the fish to the new water over a period of several hours, if at all possible.

Some fish particularly enjoy slightly alkaline waters like yours, including many African cichlids. All but the most delicate softwater species should be fine, though; they may be less apt to breed in high pH water, but otherwise they'll be perfectly healthy. You can also lower the pH a little by adding organic material such as oak or Indian almond leaves or driftwood, which will slowly leach tannic acid into the water.

 

[OldMan47]

The high pH is a problem that I had in the past. My tap is about 7.6 but my pH always went over 8. I fianlly pulled out one of my decorative rocks and put it in a bucket of water for a few days. Th water went right up so I removed all the rocks I had that looked the same. Now my pH is stable. I had done the fizz test with mild acids, don't remember if I used vinegar or lemon juice and it had not responded so for a long time I thought the rocks were OK. I eventually found out I had been wrong to trust that test.