Not that I'm trying to push this idea to you but if you were to leave the close loop in the stand but extend the remaining sump and equipment into the basement, will it be that much work? I can't see all the piping between the sump and CL pump but I see two drains into the sump through the bulkheads. For that two connection, you would only have to cut the 1.5" tubing, add a coupling, and then extend the 1.5" PVC into the basement where the sump is located. Then find a return pump that you can connect from the basement to your return lines. Keep in mind you don't need a huge return pump since most of your flow is from your CL.I run my 180g sump in the basement and it is so SWEEEEEEEEEET
I'm only using a mak4 for the return at 14' head height but soon I would like to upgrade to a high pressure iwaki55 or pcx-55 when I get my other tank set-up.Think about the pros and cons for your system but I would highly recommend moving the sump to the basement if you can, if you are able, and if you willing to do the extra work.