Thats not a bad idea, any sites yould recomend for fresh water sumps? The bulk if the info i find on them is for saltwater.
This site is basicly the best one there is for that info. There's a ton of info in the diy section and this section for how set them up. You can make sumps out of old fish tanks and set them up however you like. Look into bean animal and herbie drains watch a few videos on how they work so you feel comfortable with them. Duel return pumps are a great idea, and should be double the size of your target turnover for head loss. Plumbing will need to be sized appropriately for your target turnover there are charts to figure that out on here as well.