Keeping your aquarium cool WITHOUT a chiller?


Do you run a chiller on your tank?

  • YES

    Votes: 76 11.8%
  • NO

    Votes: 544 84.7%
  • Other (please explain)

    Votes: 22 3.4%

  • Total voters


Community Member
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Jul 27, 2020
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2525 Günselsdorf
My tank temp setting on the P4 is 26.5 C. With the warmer weather, if the AC is not on in the living room, it has gotten up to 28.3 during the day.

28.5 C is probably the upper limit that I would tolerate. So far, I have seen no negative effect of the current temps of the tank. Keep in mind that when the temp hit 28.3 it was a peak and that the temp came down as the day cooled down so it wasn't at that temp all day long.

With the AC on the temps don't get near that high.

I have three of the GHL 5 fan units on the tank and they do help but for me they are more of a backup of the AC. As long as the AC is running all day long, the tank temps stay around 26.6 to 27.2 or so...

My advice is that, if you have the budget, get the GHL 5 fan unit anyway. It will help reduce any extreme temp swings during the day if you need it. But like I said before, I have been diving in tropical waters with temps of 27-28 and beautiful corals. But that is the sea and not a reef tank.

On my previous 250 liter tank I just had a table fan blowing across the surface and that did the job very well. But I didn't have five Mitras 7206s over the tank either in an enclosed "canopy". Maybe try a normal fan first?
Thanks for the reply, my tank has also 250 liter, I live in Austria so high Temperatures are here pretty rare . I will buy the GHL Fan just because i found it at a good price .


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Apr 12, 2020
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North Carolina
Noctua makes an industrial grade waterproof fan model, I linked it in a previous post. A little expensive but come with a ridiculous warranty and are totally sealed internally.

Thanks re: the print quality comment. I use really nice printers and am meticulous about the plastics I use, climate control, maintenance, and calibration! Many people still think of 3D prints as “rough” or for prototyping, but properly done you can get a high quality end product.
Can you resend the Noctua industrial grace waterproof link for us that missed it the first time around - love your setup.


2500 Club Member
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Oct 3, 2015
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Reef Diaper