internal overflow still a viable design?


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Apr 6, 2020
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For my next 125 gallon tank setup the space outside the tank is at more of a premium than the space inside - therefore I am hoping to avoid the internal/external overflow design that has become extremely popular (shadow, modular marine, fiji cube, etc...). I am hoping to build an internal weir with nothing but plumbing outside, as seen in this screenshot of a BRS video from 2011. I would use 3 drains and probably use a T so the drain pipes can have a vent if needed for tuning.

Is this design noisier than the most modern products? Or did it just fall out of favor because of in-tank space requirement?

This is basically all that Glass Holes sold, iirc.

2021-07-16 17_10_24-Adding a Sump and overflows to our Reef Tank -- Ep_6 How to set up a saltw...jpg
Top Shelf Aquatics


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Aug 12, 2018
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I would think it is indeed a matter of recapturing ‘prime real estate’ from inside the tank. Obviously, many custom manufacturers offer both internal and external setups— such as SC Aquariums and Innovative Marine. If in your case, the prime thing is space behind the tank, then you have to do what you have to do, I suppose. Best wishes!


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Grove City, Ohio
Take a look at any "reef ready" tank. They use big ugly corner boxes. When I set my system up I used a internal box and mounted it dead center in back to leave both sides open for viewing. Works great imo.

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