afew:

Needed to cover rods: 15 meters, 400-500 tons water

I thought that was 15 feet, not metres. Anyway, I estimated 650 tonnes of water upthread, but with the expected evaporation you'd probably need more water than for a cold pool.

So, in what may be my last act of "advising", I'll advise you to cut the jargon. -- My old PhD advisor, to me, 26/2/11