Advantage and Disadvantages of Overflow box

[Shannon Tan]

I am planning to set up a 20g frag system with an overflow box leading to a sump. But i am not sure about the size of the overflow box and what pipe size I need.

 

Please advise

Thank you.

 

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[R0B]

Overflows act as barrier reducing risk of pipe blockage and (assuming is an external overflow) typically allow for easier access to plumbing. Disadvantages (few)... added cost, tank needs drilling.

Regarding size....  well that depends on two factors. One is the amount of water needed.  So a 20g would need just 450L/Hr of flow for 5x turnover. Which could be handled by as little as 12mm pipe (Although best to size up to 16mm). The second factor is the type of overflow you plan to use; Durso, Herbie or Bean Animal?  Bean Animal is possibly the most popular as it is regarded the safest and the quietest method.  The type you select will have either one or two main drains with potential of an extra emergency in case of Durso and Bean Animal. Manufactuers typical have size ratings for their overflow boxes so check them out when choosing box size. But, regarding actual size of pipes you need, well sometimes this is dictated by the overflow manufactuers, however a good rule of thumb is that the drainage should be able to carry at at least three times as much volume as the return line.  So a 16mm diameter pipe has an area of around 200mm2  whilst a 20mm pipe has say 315 and a 30mm pipe around 700.  So a single 16mm return would need either 2x20mm drainage pipes (bean animal) or 1x30mm (for Durso or Herbie method). Hope that helps.


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[JiaEn]

Do take note a bean animal style overflow can take up a significant space due to the number of pipes used. Therefore for a 20G aquarium,  it may or may not be practical. 

Is your aquarium pre-drilled?  Or are you going to make one? 

[Shannon Tan]

I do not plan to drill the tank. The overflow I plan to install is a HOB overflow box. I have concerns that the overflow box will not have the minimum required drainage my tank needs for a mix frag tank. Keeping in mind that I do plan to keep SPS in the foreseeable future

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[JiaEn]

3 minutes ago, Shannon Tan said:

drainage

The dt-sump turn over does not need to be excessive. It's always more economical to make use of WM to provide flow for the DT. 

 

The reliability of a HOB overflow box, that's another issue altogether. 

[R0B]

I do not plan to drill the tank. The overflow I plan to install is a HOB overflow box. I have concerns that the overflow box will not have the minimum required drainage my tank needs for a mix frag tank. Keeping in mind that I do plan to keep SPS in the foreseeable future

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Most overflows can easily handle a small tank. My concern if any would be with a HOB you carry the greatest risk of major catastrophic failure. If for any reason the siphon breaks then you will end up with an overflow (as the sump continues to pump all the water into the tank). Further any auxiliary items like chiller will also shut down / damage due to lack of water. Thus, this maybe something you would want to reconsider...





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[PulposTriste]

3 hours ago, R0B said:

Most overflows can easily handle a small tank. My concern if any would be with a HOB you carry the greatest risk of major catastrophic failure. If for any reason the siphon breaks then you will end up with an overflow (as the sump continues to pump all the water into the tank). Further any auxiliary items like chiller will also shut down / damage due to lack of water. Thus, this maybe something you would want to reconsider...





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Agreed, flooded my room a few times because of blockage in the pipes/loss of siphon from power outage. Now I know always to have emergency drain and keep the HOB overflow constantly primed.

If you really want to have one and keep it small, go for Herbie (don't forget the emergency pipe), dursos can be quite noisy in my experience, and bean animal is too big.

I've kept a mixed reef frag tank with large HOB filters haha, it's more important to have wavemaker flow imo.

 

[Shannon Tan]

So how do you guys recommend the best way connect my frag tank to the below sump? Drilling the tank?

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[PulposTriste]

I mean, I can't think of another way haha.

You can always have someone who has experience to do it for you. Maybe Vincent from AA?

 

Also as ridiculous as this sounds, I feel like a classic tank top sump would be a good choice. Obviously not the prettiest, but can save you lots of headache. Only need one pump and let it overflow into your display. Something like this maybe? I'm sure with some creative touch, you can make it look perfect. Plus you don't have to destructively modify your display tank too.

 

[R0B]

So how do you guys recommend the best way connect my frag tank to the below sump? Drilling the tank?

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As long as your tank doesn't have tempered glass then yep drilling is best way.

If you are stuck, happy to help you. I can come drill your tank for you. I have drilled a few tanks before. It isn't as scary as you may think.

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[Shannon Tan]

Thanks Rob!! My tank is made with crystal glass. Hahaha I'm really apprehensive about drilling my tank. But I'll get the necessary overflow parts if you could help me to drill my tank

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[R0B]

No worries. I just pm'd you.

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