You're pH is pretty high. RCS are hardy so if they have started breeding for you it means they have adjusted and I would leave it alone, stability is more important than "ideals" in my opinion. But that is probably a factor in why you lost 15 of the 20. Just don't plan on keeping any Crystal Shrimp without a lot of intervention, they like their pH low.
Your kH is also pretty high.
Lastly the TDS is high.
It looks like you may need to switch to R/O water completely or a 3/4 R/O and 1/4 tap mixture.
What are the values of just the tap water straight from the faucet?
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