Actually the main driver was to have complete silence regardless of box utilization. Hence the size of the bucket to absorb all noise from pumps.
Actually 27% was humidity. 25 C was room temperature, 18 C - water temp.
I used this radiator with standard fan and three of these pumps for resiliency. And standard 5/16 ID vinyl tubes.
Radiator mounted outside the house - hence “extreme” GPU cooling during winter - lowest was 9C with 100% utilization: screenshot. To prevent water freeze added a quart of propylene glycol to water.