You could use something like this on the intake side to prevent something large from getting sucked in and plugging the system (like a turtle).

https://www.agridrain.com/shop/c52/bar-guards,-standard/


www.hoosierpondpros.com


http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).