First off I will mention that this through the wall skimmer for Intex pool guide is on a hard sided or framed Intex not the Intex Easy Set with the inflatable ring top. You need the semi-rigid side to support the weight of the skimmer and hoses.
With that said, a through the wall skimmer is the easiest way to keep your pool sparkly 
clean. It will skim the floating items off the top before they get water logged and sink to the bottom. There is a basket with small holes in the skimmer that allows the water through but collects the leaves and bugs to dump out. Skimmers also have a vacuum attachment making it a breeze to remove any other debris off the bottom.
Install a Through the Wall Skimmer When the Pool is Empty or Full?
There are some questions about whether to install the through wall skimmer when the pool is empty or full. I would recommend doing it when its full or at least almost full. Perhaps just below where the skimmer will be installed. The sides will move around a little until the water is in and stretching the pool into its final place.
You can do it with a full pool. You just get a little wet when drilling the screws through!
Installation:
Now lets get into the installation. It’s actually fairly easy once you get past the fear of cutting a hole in your new pool! If you are even slightly handy around the house it should be quite easy. Be sure to follow the manufacturers instructions as each skimmer can be a little different.
The first step is aligning the outside skimmer and gasket with the inside ring and gasket. Then drive the screws through the liner clamping it all snugly. At this point the only holes in the liner are the screw holes. Depending on the type of siding you may need to mark the screw holes and predrill.
Once the screws are tight, the square hole can be cut out of the siding/liner.
I recommend this Hayward skimmer. It has amazing reviews including those installed on Intex pools. It includes everything you will need.
Adding a skimmer to an Intex pool is the best upgrade you will make to your pool. You will be wondering why you didn’t do it sooner!