Zcash Faces $16 Million Locked in Its Oldest Privacy Pool
The NU7 upgrade makes Sprout transactions invalid, forcing holders to move their ZEC out of the oldest shielded pool. At the same time, Zcash is cutting block time from 75 to 25 seconds.
Key Takeaways
- Zcash holders have less than a day to pull about $16 million out of the oldest Sprout privacy pool.
- After the NU7 upgrade, version-4 transactions will be rejected, making the remaining Sprout coins unusable.
- NU7 cuts the target block time from 75 to 25 seconds and does not directly change Zcash's total supply.
Zcash holders have less than a day to pull about $16 million (€14.2 million) out of the network's oldest privacy pool before an upgrade makes the remaining coins unusable. As of Thursday morning, the Sprout pool still held 12,226 ZEC, down from about 22,263 a week earlier.
Sprout Is Running Out
The biggest outflow came on Sunday, when about 9,094 ZEC left the pool. On Wednesday, only another 40 ZEC was added, which suggests that many holders have already moved their coins or that part of the remaining balance is harder to access.
Sprout is Zcash's oldest shielded pool and launched in October 2016. It was the first live use of zk-SNARKs in a working crypto project, an important step for blockchain in the crypto market. By now, Sprout has been overtaken by newer pools, leaving the old structure with only a small share of the network's private balance.
What NU7 Changes
The deadline is tied to NU7, the network upgrade scheduled for block 3,543,405. At the time of writing, the chain was at block 3,542,391, which works out to about 21 hours until activation, although the exact timing depends on how quickly miners find new blocks.
After activation, NU7 rejects version-4 transactions, the only transactions that can spend Sprout coins. Anything still in the pool will then be unusable under the new rules, even if the owner still has the private keys. The coins will still remain part of Zcash's issued supply.
Why This Matters
For European crypto followers, this shows how a protocol can phase out old privacy layers without directly changing the total supply. That matters for users who still have old wallet records or zc addresses, but also for anyone tracking how Zcash is gradually simplifying its privacy infrastructure.
NU7 also lowers the target block time from 75 to 25 seconds. In theory, that should make transactions confirm faster, although that alone still says nothing about final network activity or Zcash usage.
The earlier Ironwood upgrade had already shown that Zcash is phasing out older shielded pools step by step. That migration already made it clear to users that private balances cannot stay in old structures forever.