Brings me back to my favorite discussion about skimmers in nano tanks. What are you seeking to change by adding a skimmer? Are the corals and other life not out competing the nuisance algae with the water changes? Or are you seeking to add a skimmer because that's what we do?
skimmers can be extremely beneficial in a nano, and they can be a waste of valuable space and money.
i have a thread on the subject, albeit not much on skimmer reviews, but member
@Luno posted a pic of his modified $40 skimmer that was pulling out sludge :
https://www.reef2reef.com/threads/nano-tanks-are-protein-skimmers-sufficiently-effective.360238/
Fwiw, I had the Hydor nano, since it was the only one that would fit inside my CPR HOB fuge, It pulled out light tea regularly, but my cheato and corals were keeping my NO3 and PO4 too low - well actually leaving behind a bit of PO4 making a nice environment for the cyano.
I decided to remove the skimmer and the cyano disappeared as the NO3 and PO4 ratio was better for the corals to out compete the cyano.
don't get me wrong, I am neither for nor against skimmers in nanos, it's my opinion and experience is that it shouldn't be an automatic addition, but rather to address the need to remove organic waste. Organic waste can be beneficial, unless it results in excess nitrates. I recommend reading
@Tony Thompson post in the thread on this.