# Question about overflow box capacity



## Ben (Nov 6, 2010)

My first post here, excuse any errors in etiquette... I have a 75 gallon reef tank that I was honestly too impatient to drill for a sump. So, I want to buy an overflow box and run a sump through that. My question is, what capacity do I buy? I remember from my past saltwater experience that bigger is better when it comes to filtration. Should I buy an overflow rated for the next size larger tank? I found the following capacities and tank size recommendations on a popular aquarium/pet website.. 

300GPH for 75 Gallon Tank
800GPH for 125 Gallon Tank
1000GPH for 200 Gallon Tank

I am considering the 800GPH with the thought that the 1000 would be a bit too much water flow. Any recommendations? Any type/brand recommendations? 

Thanks for all your help!


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## beaslbob (May 29, 2009)

Ben said:


> My first post here, excuse any errors in etiquette... I have a 75 gallon reef tank that I was honestly too impatient to drill for a sump. So, I want to buy an overflow box and run a sump through that. My question is, what capacity do I buy? I remember from my past saltwater experience that bigger is better when it comes to filtration. Should I buy an overflow rated for the next size larger tank? I found the following capacities and tank size recommendations on a popular aquarium/pet website..
> 
> 300GPH for 75 Gallon Tank
> 800GPH for 125 Gallon Tank
> ...


Before you buy an overflow box you can build an overflow with about $20 worth of pvc. If you make it too small just use larger pvc pipe. 

See:

http://www.aquariumforum.com/f37/pvc-overflow-3492.html

To size your overflow pull out your pump's specifications and measure the height between your pump and the top of the tank. Get the gallons per hour. (The actural gph will be less so that rough figure will be safely higher then what you will experience.) Then get an overflow rated that gph or higher. To be safe the overflow should be at least 25% higher or so.

If you have never setup a sump before I also recommend you get a couple of containers and your equipment in your garage and play around for a few hours untill you get it right. Much better to flood the garage then the livingroom. *old dude

and feel free to keep asking questions.

with my answers worth at most .02


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## Ben (Nov 6, 2010)

Thanks for the super fast response. I'm not quite sure I'm mechanically inclined enough to pull this off. I may give it a go, thanks again!


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## GetITCdot (Aug 4, 2009)

also take a look at this post http://www.aquariumforum.com/f18/please-please-chuck-some-easy-advice-9256.html


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## beaslbob (May 29, 2009)

Ben said:


> Thanks for the super fast response. I'm not quite sure I'm mechanically inclined enough to pull this off. I may give it a go, thanks again!


Welcome. rapid response was random.

I say go for it. You'll be surprised at how easy PVC is to work with. All you need is simple hand tools. Or the power tools you may already have.


my .02


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## WhiteGloveAquatics (Sep 3, 2009)

I love my overflow box, CPR100 matched to a model 9.5 mag drive matched to a aquapro 175 wet/dry.


PVC overflows look like crap, if you have a nice reef tank a clear overflow box would be aesthetically better as well they will break siphon unlike a PVC unit will until its too late.


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## beaslbob (May 29, 2009)

WhiteGloveAquatics said:


> I love my overflow box, CPR100 matched to a model 9.5 mag drive matched to a aquapro 175 wet/dry.
> 
> 
> PVC overflows look like crap, if you have a nice reef tank a clear overflow box would be aesthetically better as well they will break siphon unlike a PVC unit will until its too late.


One of the adjustments you must do IMHO with either an hob overflow or drilled tank overflow, is to insure if the drain to the sump fails, the display does not flood.

my .02


learned after 2-3 failures. *old dude


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## WhiteGloveAquatics (Sep 3, 2009)

thats alot of the problem with DIY ones, to insure it wont flood you must set the height correctly as well as make sure your wet/dry or sump can handle a minimum of 25% of the tank volume. 

Ive only flooded out when I forget to shut off the new water going into the wet/dry. 

I use CPR boxes because $100 bucks is cheap insurance to me as my fish rooms are 100% finished as in tile,drywall,trim,paint ect.(no, my wife has not learned what a real fish room should be, she likes everything presentable, i like everything functional.)


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