What pump size and type filter

[carperama]

Thanks for the advice. I did think about running in parallel so I put in an extra bulkhead just for that purpose. I figured to try in series first with two 2" pipes coming into the first barrel then switching to 3" through the rest of the barrels than a 2" pipe returning to the pond. I can always switch to the parallel system since I put in a bottom drain for it just in case. I haven't found any information if the water level will drop in the barrels or not with the pump behind the barrels, I don't think there will be much different using a 3500 GPH pump? I have a 7000 GPH pump as well I can try. Since I don't really know what i'm doing I figured having two static and two moving beds with the over stocked pool would be best?

[Grumpy]

You should be good with flow now using two 2" inlets.

You will have some draw-down into your static barrel, but little draw-down between the remaining barrels as long as the matala pad and media doesn't clog, and your bottom drains remain clear and unclogged.

Other folks have more experience with the success of your bio plans treating your large fish load.