Have you read their FAQ on their website? TIDES

“Our reward scheme is called Transparent Index of Distinct Extended Shares (TIDES). As blocks are being mined, they generate the reward by a weighted percentage of effort to the most recently found proofs. The proof period funds are distributed across has been chosen such that each proof should be paid on average 8 times. Instead of a set amount of bitcoins per proof, the block reward is divided by percent, so transaction fees are included. Because of this design, each payout to you is fully auditable. Previous implementations of similar systems such as PPLNS would distort the payouts owed to miners by using “shifts” and much smaller proof windows, resulting in miners getting significantly less accurate payments for their contributed hashrate. TIDES is the most accurate payout scheme available in Bitcoin today and unlike other schemes like FPPS it does not require the pool to serve as a custodial intermediary for payment processing.“

Also see: https://d-central.tech/ocean-pool-a-new-wave-in-bitcoin-mining-decentralization/