Low Ph From Tap, High Ph In Tank?

[catxx]

Now I get ph crashes that are the other way round in mature tanks, but right now I'm baffled. The ph from my tap is around 7.2, in my tank (mature 30l running a few years, heavily planted, bogwood, bit of slate, happy healthy fish, metallic livebearers, and shrimp, but did move towns a month ago) is more like 7.8! I'm going to go test my other tank in a minute. Ammonia is at 0. Not yet tested gh/kh but can. Using liquid kits.

Will be setting up new larger tanks in the coming weeks and acidity is playing a big part, hence the testing.

Anyone sciency able to explain???

 

[Truck]

It's because the water board saturate the tap water with CO2, to stop it forming limescale in the pipes, after it has left the pipe, where it is stored at high pressure and is in the tank at low pressure, the gas escapes and causes the PH to rise, CO2 makes the water acidic because when it dissolves in water it creates carbonic acid.

7.8 is nothing to worry about.

 

[catxx]

Ahhhhhhh that kinda makes sense. I leave water out with a heater plus dechlorinator for a few hours prior to water changes so that explains why the critters are not effected.

And 7.8 is a psi when I want to keep acidic loving unusual plecos who like 7.0 and I'm not tech enough to mess with RO etc