Whirlpool is a powerful Coinjoin tool built into the heart of Samourai Wallet. When adding bitcoin to one of the pools, it’s split into multiple separate UTXOs, all matching the size of the pool you entered.
All UTXOs in the pool are identical, increasing your anonset exponentially over time as further remixing occurs.
A whirlpool tx0 will always result in doxxic change, an amount unable to fit in the pool, returned to your wallet marked “do not spend” & safely separated from your post-mix wallet. This change still contains deterministic links & should NEVER be combined with other UTXOs, most notably those in your post-mix wallet.
So, what can you do with this change?
Depending on the pool size entered & size of the change, first check if you can add it to the next pool size down, repeating this, cascading down the pool sizes one at a time. I recommended sending tx0 change into whirlpool alone & never with other UTXOs.
Eventually, you will have an amount too small to enter any other pool. You could save this in your wallet, marked as non-spendable for future rounds with other doxxic UTXOs; however, I prefer to remove these UTXOs from my wallet entirely, drastically reducing the possibility of accidents.
My favourite method of using small doxxic outputs is to send them to an anonymous Bitrefill account & use the sats to purchase vouchers for famous high street & online stores. Still, you could also use swap services like Fixed Float or donate them to your favourite open-source projects like Samourai Wallet or RoninDojo.
This article is only a brief explanatory guide for beginners, the technical details go much deeper & others have found even better ways of dealing with change.
For a more detailed explanation, check out the Samourai Wallet Wiki or the many other excellent websites available from other community members.