Waterbox marine 70.3

[Freshly]

I have a waterbox marine 70.3 I am getting a gargling sound from the overflow return in center rear of tank can someone tell me how to make it quite. I have alwready tried adjusting flow rates on return pump and ball valve with little success. Also does anyone know if you can buy,make or have made a cover to silence that area which is aprox 4 x 36in

 

[Hemmdog]

Welcome to reef2reef! Ball valve or gate valve? Should be gate valve to regulate flow.

 

[Fezbearer]

Marine 70.3 has a ball valve