I have a Tunze internal skimmer. They are quiet but they do make a noise. Like a white noise. If it’s bothering you, maybe turn it off during the night.
My nitrates were getting too low so my skimmer is now off during the day and only working at night.
@Enzoo92 If you want a complete internal kit, there is a really nice one that’s available in Europe. Here in North America we have to buy it separately. That’s what I did. In the kit, there is the Tunze ATO, Tunze Skimmer and Tunze internal filter. I’ve been using mine for a year and I can assure you they’re good quality and do a good job.
They come in three sizes, this is the larger size (what I have for my 75 gallons or 280 liters) :
Hi-Tech für Aquaristik
www.tunze.com