Hard Water (reducing Hardness)

Hi all,
I am considering using a 50/50 split of RO/tap water in order to reduce the Hardness of my water. Using the API test kit on my tap water I get a KH of 14 (250.6) and a GH of 19 (340.1). I have a lot of tetras in my tank so I am assuming by halving the KH / GH readings I will be providing them with a more suitable environment to live in.
The Ph averages out at 7.3 as I use CO2 injection for my plants.
I perform water changes daily equating to about 50% of the tank volume a week so I am assuming I won't shock the inhabitants of the tank by doing this.
I also have a lot of shrimp in the tank but I am assuming that a 50% decrease in the hardness of the water should be OK for them.
Any thoughts would be greatly appreciated as to whether this is a good idea or not.

It’s been nearly six months and my tank water is now composed of 50/50 tap/RO. The fish seem a lot happier and their coloration and growth has improved. Plant growth has also improved with a subsequent reduction in the amount of algae present. All in all a good result.