Dying RCS

[ectankman]

I put 10 RCS and 4 Amano's in my 29G low tech planted tank (hornwort and water sprite are the main players) a little over a week ago. One of the RCS died early, but everything seemed to settle down until yesterday, when two more died. On the third one that died there was a noticeable gap in the shell between the head and body (see photo), which leads me to believe that they are unable to molt and are dying in the process. I've had two or three successful Amano molts, so this caught me off guard.

The tank was planted for over a month before I put any shrimp in it. I use water from the tap, and toss in some Dr Fosters and Smith Chlorine Neutralizer; Ammonia, Nitrite, and Nitrate are all 0; Temp is around 77; pH is 7.6; and GH is 14ish. I'm thinking those last two could be my problem, as I've read that high pH + high GH can lead to molting issues, but I'm curious if anyone has any other thoughts and recommended solutions. Appreciate the help!

Also, here's the DC tapwater report, pages 11-13 have various specs: https://www.dcwater.com/sites/default/files/2017_dcwater_water_quality_report.pdf

 

[Floop123]

Is the tank cycled? Some shrimp just can't molt correctly during the stress of moving to your tank.

 

[Fresh2o]

Early on, 2 out of every 3 shrimp purchased from the LFS would die while molting. I bought a test kit to measure KH and GH and got 5 and 9 ppm, respectively. Those are acceptable values. I suspected that the cause of death was due to low calcium levels but did not have a test kit to back up that suspicion. I have no idea how well the RCS were handled prior to getting to the LFS so there may have been a precondition as well.
I added a few chunks of cuttlebone to boost the calcium and about a month later ordered some shrimp from AA member JungleFowl. The survival rate was much higher (>90%) and spawning followed soon after. Perhaps these were from a much healthier stock. Both LFS and online purchases were drip acclimated at least an hour prior to introduction.
Nice to include the water report. The first thing I looked for the the copper levels and they appeared to be unremarkable.

 

[Floop123]

Is it cycled?

 

[ectankman]

Yes. As of yesterday, here are the tank stats:
Ammonia: ~0.25 (though I read the API test will show a green tinge even in fully cycled tanks)
Nitrite: 0
Nitrate: 0 (tank is fully planted w/ nitrate hogs)
GH: 11
KH: 5
TDS: 250
pH: 7.6

I think I'll throw some blanched kale in there to ensure there's enough calcium in the diet per Fresh2o's recommendation. If that doesn't do it, maybe I just got a bad batch of cherries.

 

[Floop123]

Do you mind telling me where you got them?

 

[ectankman]

The Shrimp Farm, ordered online.

 

[Floop123]

Maybe they will give you a refund.

 

[Fresh2o]

I think refunds are given if you can provide evidence (pics) of DOAs when unboxing the shipment.
Mine died weeks after introduction (whenever the next molt cycle was).