1.) You bought from Aquatic Arts (I have a feeling that imported Neos might do better in Caridina parameters, so wouldn't necessarily recommend putting them on a non-buffering substrate - just changing your minerals)
2.) You are using KH on a soil that should have 0 KH
3.) You might be over-feeding Bacter AE
4.) Shrimp pellets and algae wafers may contain too much protein - their diet should be algae based. Many "algae wafers" don't even have algae within the top 5+ ingredients! Throw in the fish food... well, just too much protein
5.) The CO2 might be an issue
Re: Shrimp in low pH.... there are people keeping shrimp in tanks where the pH is in the 5's and I might have heard of someone even keeping shrimp in a tank in the high 4's???
Since this was brought up.... I had to check my own tank... lol
SL-Aqua buffering substrate, RO water and GH minerals. Prior to changing out the substrate, the pH probably was around 7.5 ish. The API kit registers a 6 pH now, and it's brand new. I've had the kit for less than a week. I then used my Sera kit to test the pH and it's saying about 5.5 pH? Tank has Bloody Mary, Yellow King Kong, and a Caridina Sp (looks like amanos, but not). All were in the tank prior to switching out the substrate. I did not acclimate them or even let the tank settle.... I literally emptied the tank out, rinsed it with cold water, scrubbed 3 walls, threw in the new substrate, refilled with remineralized RO water and GH minerals with plants, then dumped the shrimp back in. I only know for sure that I've lost one shrimp, and it was a Caridina Sp. (the not-amano).
I've been struggling with Neos, regardless of where I get them or what type (Cherry, Yellow, Bloody Mary...), what water I keep them in (straight tap kills them, RO and minerals didn't really improve survival after trying remineralized tap - diet change did work until two separate people unintentionally killed off several shrimp within 3 weeks....) so if I lost them then I lost them. So far, the bloody mary are still doing okay as far as I can tell. It's been at least 3 weeks since I changed out the substrate.
So take that as you will...
Okay, taking this all in as I can. I'm a quick study, but water parameters have this domino effect that I sometimes do not consider fully.
I am going to buy some SS GH+ and start using that as my remineraliser.
I know that I can keep shrimp on ADA, I just think I've chosen the wrong species. I should aim for some caridina as they will be better suited to the soft water.
I will lay off on the protein stacked foods, any suggestions on what I should use as a staple food. A food I could feed daily without harm if I needed to.
Seems like your substrate change went pretty well in reality, I'd expect some decent losses coming from a full change like that.
Once again, this is my high tech, so basically it's for the plants not shrimp. But I still just want the most info I can get to see why I am being so unsuccessful.
I appreciate all the advice by the way everyone. This has quickly become one of my main aqua goals, to be successful with breeding shrimp.