the pump simply isnt 'submerged' you instead connect it via hose to the inlet from the res bucket. (Have you considered a larger rubbermaid tote rather than another 5g bucket for the res? seems youll top off that res constantly) Peek at a few of the How-To and DIY posts for RDWC builds in this forum, theres some nice ones, and they point out the 'dont forget this! I did, and it sucks!' type shit, lol.