Hi Grace,
I don't know how you data looks like. But the following are general rules that helps reducing spurious barcode.
For low complexity barcode library, I recommend to set option -z be -1 so that make the cluster merging decision solely based on the distance.
For the second relative large barcode library, you can increase -z value and distance(depends on the barcode length) to reduce spurious barcodes.
Based on our observation, cluster size under 3 is very hard to tell if they are true barcodes. You can set a threshold to remove low-frequent barcodes after clustering. The threshold should be chosen based on your experiment design.
LMK if you have other questions.
Any advice is welcomed to improve Bartender software.
Best,
Lu