RO water advice for a CO2 Tank

Hello, I would appreciate some advice on a water change issue. I currently have a tank with CO2 but have just added crystal shrimp, previously I have been using tap water which is quite hard GH 8, KH3, PH 7.5, when I run with CO2 it drops to GH6, KH0 and PH6.

This is my first water change since adding the shrimp and have got some RO water and Salty Shrimp GH. I want to use this for the water change rather than put my tap water in. TDS of the Tank Water is currently 180,do I adjust the TDS in the water change using the Salty Shrimp or so I make it slightly harder due to the CO2?

Thanks in advance