Hi guys,
I am having a problem with regulating the TDS and the GH value in my tank.

I use R/O water and re-mineralize it with Borneo Wild GH+.
The fresh water always has a TDS of 150 and GH of 4.
However in my shrimp aquarium the TDS is 200 and GH of 2!

The shrimps look active. However, they don't eat food I am introducing to them (however they are eating around the driftwood - so not a concern) and they don't reproduce

I really can't figure it out what is lowering the GH value and increasing the TDS.

I have 55L tank, heavely planted with a big drift wood in it.
Soil: ADA Amazonia Light

Any ideas would be very very welcome.

thank you,