Why?

The 20G L CRS had some newborns a few days ago, I spotted 6 three days ago, then 2 two days ago, only 1 yesterday. It just has to be this hard for me.

Environment:
20 G Long (set up in early March, shrimps introduced in about 4 weeks, it was cycled before shrimps)
Akadama 2" to 2.5"
UGF air driven
Up Aqua EX 120 HOB Canister
One extra airstone
My DIY nitrate filter
13w clipped on CFL light
Tons of peacock and java moss, 1 lone java fern, some amazon frogbits (they haven't been doing well), some hornwort. Two pieces of DW with moss on it, each about 10" x 8".

Temperature: 19 - 23, got up to 24/25 a few times but never stay there for more than 8 hours.
PH 6.5-6.8
TDS 150 - 160
GH 6-8
KH 0-1
NH3/NO2 0
NO3 5-15

20 - 23 adulat CRS low grade
10 OEBT sub-adult

A few more shots on part of the tank,

I have probably lost close to 100 baby CRS by 5 or 6 releases. Adults are fine, OEBTs are thriving and grow fast, and no baby CRS survived more than a week.


I need to move this tank so will have to tear it down. I don't really care that much about the breeding activity in this tank but just can't figure out what is wrong. The shrimps in this tank mostly were put there to wait for the permanent home ready (it was ready 3 days ago).