mixing R/O with tap to lower hardness

[canon8838]

I have just bought a R/O unit and was planning on mixing it with my tap at 1g of tap for every 4g of R/O. I was wondering what every one else uses as a ratio for mixing R/O???

 

[farm41]

Depends on the species and the desired outcome. My tap is 6.8Ph, and EC 300µS, with some fish I want <100µS and a Ph <6 so I will use very little tap, mostly RO and some peat treated water.