You have no breaker available from the panel with that kind of capacity, so it's a short run from the panel at the right of the stair and up to a secondary panel for those new breaker.
or you just keep pumping and weekly muriatic acid treatment
Many thanks for your prompt reply. It's as I suspected but nice to have a confirmation. Re the Muratic additive for the remaining hand pump, we use a third fresh water, 1/3 washing up liquid and a 1/3 Muratico (we're in Spain) and use a squirt after each use. What's your once a month recipe?
Thanks again