“I have a 9004 in the rear chamber on my 36 gallon and I've been very happy with it so far.”

83% of 6 verified owners recommend the Tunze Comline DOC Skimmer 9004, based on real owner verdicts aggregated from Reddit, enthusiast forums, and YouTube.
The headline score reflects owners (Reddit, enthusiast forums), independent lab tests, blogs with no affiliate links, and YouTube owner-comments when they line up with owners. is shown for perspective but kept out here — hover the i for why.
Synthesized from what Tunze Comline DOC Skimmer 9004 owners say — not a spec sheet.
“I have a 9004 in the rear chamber on my 36 gallon and I've been very happy with it so far.”
“Worked well enough, but ultimately found it wasn't needed on my 20g nano.”
“Use the Comline DOC Skimmer 9004 by Tunze in my smaller build and works quite well.”
“I do have a tunze comline doc 9004 in my 40 and it does export a lot of gunk.”
“still breaking it in, on day two. So far so good.”
“I absolutely love my comline skimmer.”
Practical notes owners raise — setup, quirks, and issues to watch for. They don't say whether the person likes the product, so they're not counted in the score, but they inform the pros, cons, and who it's for.
“For a skimmer, we use a Tunze 9004 Comline Doc Skimmer in our 40 gallon breeder (which was a recommendation right from the BRStv 5 minute guide on Youtube that someone else mentioned).”
“I bought a jbj nano uv in-line that is connected to my return pump, very slim and doesn’t take up to much room.”
“IM40g nuvo Tunze9004 skimmer Titanium BRS heater Chemipure blue A shit ton of seachem matrix Filterfloss”
“I tried but failed with xenia, montipora, Duncan, sugar canes, zoas. I really would love to have a zoa garden. Today added the internal Tunze Comline DOC Skimmer 9004 DC. Was worried about the wave maker locations and the flow. I'm not bothered with the bubbles from the filter, as that doesn't happen often.”
“Oh this worked! I even wrapped the bottom in filter floss. It's a bit weird still because the bubbles are still diffusing out, but slowly and not spread out. Thanks for the advice”
“Sometimes my outside magnets get ever so slightly dislodged from the rubber around the edge and it’ll do that, try pushing the magnet down more and spinning it against the glass and see if it catches better.”
“I’ve watched the video now and did as they said, how often will I need to be emptying the cup, it’s 0,2 liters”
“Have you deconstructed it and bathed it all in vinegar? Mine was starting to produce less n less bubbles. I took it apart, soaked it in vinegar, scrubbed everything with a toothbrush, reconstructed it n its now good as new. Mine actually had some hair wrapped round the pinwheel.”