CRS's are the most sensitive species I know of to NO3.
They are in bred like crazy and sensitive to ions.
and yet here we have a noted CRS breeder using EI and has no issues:
I've gone to 160 ppm or a tad higher for over a week with a few Amano deaths.
Far higher than you should have if you keep shrimp.
Generally, all you do is dose a little less and if the plants are effected, add a bit more KNO3 is all. The other thing is do more water changes, just like breeders do with Discus.
These are common sense approaches.
However, as you can clearly see, the CRS's are fine and breeding in profusion in Rain's tank's.
What ferts do u put in ur CRS tanks? - Page 2 - The Planted Tank Forum
I'd suggest using culls, then go from there, acclimate very slowly also, so they are use to higher TDS's from all the ferts we add etc, not just dump them in all at once like many folks do.
I've never had any issues with Cherries or Amano's, and that's after many years......
I'll try some CRS's but I have more toxiciology related interest with them.