Which pump for curing dry rock?

[Easto]

I have 50lbs of Pukani rock. It's been in bleach and acid already.

Currently it's sitting in a 125L Rubbermaid container. I'm making my first batch of RO/DI water so I can get rocking.

I have a Maxijet 1200 pump that came with my BRS dual reactor.

I also have an Eheim 1262 pump that I plan on using for my tank when the rock is done curing.

Which of these two should I use in the Rubbermaid for water movement?

Will the Eheim be too much? MJ too little?