To Sump or not to Sump...


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Dec 18, 2020
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St Louis
Hi All,

Still fiddling with what I want my filtration system to be like on my first reef tank (20g High). Right now I am running an Aquaclear 70 HOB that I modded into a refugium but I'm not wild about it. Cheato inevitably gets into the DT, I'm not really doing anything for protein skimming and I've had almost constant cloudy water (even with weekly water changes, purigen, low lighting etc.)

My question is which route should I go for additional filtration and nutrient export? Here's what I am trying to decide between.

  1. HOB overflow box intro a 10g below tank sump/fuge
    • Pros: More water volume, dedicated fuge area, additional protein skimming
    • Cons: Expensive, concerned about what happens in a power outage/siphon break
  2. HOB Fuge + Canister filter
    • Pros: Fewer additional parts, more filtration
    • Cons: Doesn't solve the chaeto in tank question, Concerned about power outage- if the power stops will a canister filter reverse siphon?
  3. HOB Fuge + HOB mechanical filtration
    • Pros: I have a bunch of HOB filters from past freshwater tanks. Fuge takes care of nutrient, HOB filter takes care of protien
    • Cons: Cluttered, additional noise, doesn't solve cheato in tank
What else should I be considering?



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Oct 2, 2020
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Illinois, USA
Thanks! My only concern is drilling a glass tank that already has fish/corals in it. Maybe the answer is just getting another tank and drilling that one?
This would be my recommendation, especially since you are using a relatively cheap tank size. I was currently dealing with a similar question and found the needed 75-gallon tank on PetCo's $1-per-gallon sale (actually $105 for a 75-gallon), which made this no question for me.

I just completed the drilling last night without any troubles. Overflows are Modular Marine 1200gph and came with the drilling template (also hole drilling guide), which made the process quite easy.

By getting this new tank, I can use my existing 75-gallon FOWLR tank for my intended sump tank and only transfer this setup to the drilled setup once. Otherwise, I would have needed to use an old 75-gallon for the sump but use it for a temporary hold for the FOWLR so I could empty and drill the current nicer 75-gallon tank. Check out my build thread if you want more details on my specific system and thought process.

The safety of a drilled tank instead of an over-the-top overflow requiring a siphon is totally worth it to me. the way, why only a 20-gallon tank? I have read many recommendations to go bigger if you can, especially since a 40-gallon breeder tank is not much more expensive. I'm not questioning your decisions, just curious what went into your decision for a 20-gallon size.
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Mar 4, 2018
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Thanks! My only concern is drilling a glass tank that already has fish/corals in it. Maybe the answer is just getting another tank and drilling that one?
Yep, that would be the best way to go about things.
Drill it, forget about any crummy HOB-equipment and live happily ever after:)
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Have you ever had a reef tank with no sump and how did it go?

  • YES and it was just fine

    Votes: 236 58.7%
  • YES but it was difficult

    Votes: 74 18.4%
  • NO

    Votes: 82 20.4%
  • Other (please explain)

    Votes: 10 2.5%
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