You are essentially koi pond size. When my dad had one, I built an under gravel filter out of pvc drilled full of 1/16" holes. Made a big rectangle with several cross pipes with T's and elbows. Buried it in sand blast gravel. We had the fountian pump pull through that. The koi loved it and reproduced several years. Keeping racoons from fishing in it was a problem.

Last edited by RossC; 11/08/22 05:27 PM.
Ross Canant