Protein Skimmer Setup

So just settin up my first saltwater tank. Have been letting it cycle for a few days w/ some live rock and decided to turn the skimmer on last night.

My skimmer is a Jewel Skimmer 3.0 (tank is around 50g w/ sand and a big ornamental ship in it and a coupla pieces of live rock atm).

Anyway I started off the skimmer with the nozzle fully turned up and the collection cup overflowed and water was going everywhere.

I then turned it down and have been slowly adjusting it to find that sweet spot but it seems that either it overflows or just fizzes.

What should I do? What is the optimum level for the bubbles? Should they be overflowing into the cup? Or just sitting in the cylinder?

Oh also, in the water the skimmer blows air at the bottom of the tank and blows sand all over the tank. Is this normal or is there a way to stop it?

Will attach pics (some of cup overflowing, others of skimmer barely fizzing)

Thanks for any help in advance

Ahh okay cool thanks!

Yeah I only just put in the rock so there wouldn't be anything at all really.

Ive currently got the bubbles to be at the level shown in the pic...is that a good level whilst it "breaks in"?