The 3/8 line is the main cause. Never had a 1/2"-5/8" or larger line clog/freeze. Go here and get one of the freeze control systems. They work, a customer has them because he is using 3/8" line, some runs are 900 feet. https://www.koenderswatersolutions.com/product_type/aeration-accessories

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).