how can i lower my kh????

I know firsthand that water softeners take out GH, but don't touch KH. The only thing I can think of is to dilute your water with safe water that tests lower in KH.
 
Place some peat in a mesh bag, container in your filter. This will tan your water a bit, though. You can also dilute with RO water or any water with a lower KH, as said.

Acids also naturally lower your KH and will drop pH accordingly.
 
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