Do I need to do anything...

[Kronos]

I currently do not add anything to my water apart from half a campden tablet and then I let it stand all night before brew day. The pH at this stage is 6.9

The pH at the end of a mash always ends up around 5.1 to 5.6 whether I brew a lager or beer.

It is worth me tinkering with the water if I am able to hit these pH values without having to do anything.

My water water hardness is 125 mg/L.

 

[Bigcol49]

Hi!
I've read that water treatment is the last thing to learn when brewing - if you are making good beer, why worry?
If you want to make great beer, then look to water treatment.

 

[ExpatBrewer]

Your pH values are on target, but there are other reasons other than pH that brewers sometimes treat their water. Without a detailed analysis of your water though it doesn't really make much sense to tinker with it and if it's producing good beer as is than I personally wouldn't worry about it.

 

[Fil]

the sodium metabisulphate in the campden tab acts instantly in neutralising the chorine/chloromides so there is no need to let the liquor stand too..

the next simple treatment option you may want to consider depending on the beer your brewing and your local water supply is to perform a 15-20minute preboil of the liquor and let it cool to strike temp, this can reduce the alkilinity by precipitating out temporary hardness in the liquor.