Look for the buffer and source
KH reflects carbonate buffering that can help resist pH change. Active substrates and organic materials may influence water differently depending on the aquarium.
Compare source water after it has aerated with the aquarium reading, and note the time of day. Plants and gas exchange can cause daily variation.
Avoid chasing pH
Repeated chemical adjustments can create larger swings than a stable reading. Neocaridina care references offer broad ranges, but a gradual stable condition is more useful than a forced target.
If pH keeps moving sharply, investigate KH, substrate, and maintenance routine. Change one factor at a time and test the outcome.
For your own tank
Measure pH at a consistent time because plant activity and gas exchange can create daily movement. Compare KH and source water before reaching for buffers. If the trend changes after a substrate replacement, document the sequence and allow the tank to settle.
Use these as general hobby references. Test your aquarium and confirm product guidance before making changes.