A lot of people (or should I say, wannabe youtubers lol) get the CrystalSkim and don't know how to actually make it work. It has 3 different combinations for the floating top piece and can also have the flow rate adjusted.
Option 1 is no basket, no crown:
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This is the worst way to set it up. It will barely work and I've seen multiple youtubers stop here and say "it doesn't work!".
Option 2 is with crown, no basket:
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This is the most powerful option. It will clear your surface in no time, but small shrimp or fish can get sucked into the skimmer. Only use this option if you have larger inhabitants. This option is also great for pickup up floating trimmings. I set mine up like this on plant trimming days to help collect plant debris, which is amazing.
Option 3 is with crown and basket:
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This one is almost as good as Option 2. I run my skimmer like this, because without the basket I had shrimp and otocinclus getting sucked into the skimmer. I also run the skimmer on a looped timer: It's on for 30 minutes, then off for 3 minutes. This change helped my tank go from 1 casualty per week in the skimmer (shrimplets usually) to literally 0 casualties for 3 months now. The downside is it is easier to get clogged with plant trimmings than Option 2, but is obviously much safer for smaller inhabitants.
Again, I've been using this exact skimmer for about 5 years with no issues once I figured it out. I LOVE it, and it also looks really nice and clean and doens't bother me (see my signature photos for examples).
My current largest tank running this skimmer is a 140 gallon rimless tank. I use the Oase CrystalSkim 350 and wouldn't ever see a reason to upgrade to the larger side 600. I genuinely think you'd be totally fine with a CS350 on your 180.