Looks like you got a skimz ib20. Very nice tanks, I know as I have one running a full ADA planted setup.
These are just as difficult as a 10lt and your biggest problem will be keeping your salinity stable as the evaporation is high and you can go from 1.025 in the morning to 1.026 that very same evening to 1.027 the next morning. So top ups are very important. Here I got a 2lt coke bottle turned upside down over the return chamber with some tubing coming out the cap and a g-clamp to restrict flow to one drop every 2 or 3 seconds and this is my auto top off. Remember to make an air hole on the bottom.
For your chambers, first chamber is filter floss and heater, 2nd is phosban, purigen, carbon and orca cubes if you want, third is your return and top off. You want your heater in the first as that will always be full of water yet your third could empty half way or more if something happens
Watch your acrylic, it scratches easy. When wiping, make sure you do not pick up some sand.
Enjoy, you have a nice tank