gurgling

I have a 16x30 inground pool, 20k gallons that I inherited when I moved into the house. There are two skimmers, no bottom drain. My 80gal sand filter sprung a leak and had to be replaced. Instead of replacing it with another sand filter I went with a Pentair Clean and Clear 320 Cartridge...

Hello. Brand new pool just finished (owner build). We just got our spa jets hooked in and noticed a gurgling sound at the equipment pad. Enough to notice while in the spa about 60 feet away. Pentair vsf running at 2500 in this video: Is this a normal sound? Can it be reduced?