Thank you for reply. I was not precise enough in my first post. I want to pump out water from tank which is on seabed at 100 meters not to surface but outside tank directly to the sea at 100 meters. It si not submersible pump because it's funcion would be to prevent tank to be overflowed (imagine that there is ingress of water in tank which must be pumped out) by water and therefore it can be regular ballast pump. Now, would this task demand too much power for pump in comparison to same task at lower depths?