Skimmer issues

Hello, I have a seaclone 100 protein skimmer that I think is working fine but im not sure. It is foaming in the main chamber, but the collection cup seems to be filling up with some sort of dirty water. I dont know if thats how its supposed to work. Also, if it is working, then, isnt the skimmer taking out water from my tank, does this remove the salt also? I was wondering if I will have to fill up my tank again.
 
The skimmer is supposed to be pulling out sludge from the tank. Depending on the quality of the skimmer and the way you've set it up, it should be pretty thick, but it will pull water out.

How much is it pulling out?
 
not much water is being pulled out, but the water is light brown. I've heard this could be because my tank is still pretty new and there isnt very much organic waste in it. The tank is about 1 and a half months old. It is a 25 gallon and has 3 ocellaris clownfish, 7 hermit crabs and 2 astrea snails so far. What do you think? Is the skimmer supposed to be working like this?
 
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