Is that not how a ionic 0 system works though Spruce I heard supplying the other RO with the waste from the 1st one killed the second RO pretty quickly ?
It does because the second is going to have to work harder.
Last time I took a reading from my waste it was 50% higher than my tap water. Our tap water is around 120 to 140 so its working from a low base. If memory serves me my r/o waste was around 175ppm.
The first r/o I had was a 225gpd unit that came from Peter Fogwill. He separated the supply from the prefilters into 3 and fed each membrane with the same tap water tds.
There were 3 ways those r/o's could be set up.
Peter Fogwill's way was the first.
2. The first membrane was feed with tap water, the second was fed from the waste of the first and the third was fed from the waste of the second.
3. The supply was divided into two and the first 2 membranes were fed with tap water. The wastes from the first and second membranes were joined together and fed the third membrane.
Ro-Man used to have a diagram of these methods on their website many many years ago. I don't know if they still have it.
I saw a couple of local cleaners r/o membranes were set up to number 3. I never saw another setup to the way mine was.
For me, it just made more sense to split the water from the prefilters and fed each membrane with that water.