Newbie sump questions

[dvgyfresh]

Hi everyone!

I recently set up a sump / overflow box for my 40g. It gurgles like crazy and makes a ton of noise (sounds like dishwasher constantly running). The over flow is CPR 102 and I don’t have the prefilter / sponge fitting on the bulk heads prior to draining , could this be why it sounds like a whirlpool? I attached a photo of return pump if relevant I have it on the lowest possible flow setting any help to make fiancé not hate the tank and make it quieter?

 

[boacvh]

Depends on the plumbing setup you have for the overflow. Googling CPR 120 I see only 1 pipe/bulkhead? Can you share some pics of your setup?
If its like that, I have a similar one, the eshopps pf 800. I fixed mine with a hoffer gurgle buster in case you want to google that one. Was a quick DIY fix for me. Completely silent now

 

[NeonRabbit221B]

For me it was all about the stand pipe size and main to emergency drain opening flow amounts