# Newbie here - overflow box/return pump question



## ShaySpins (Oct 22, 2013)

Hi all,

I've been a freshwater planted hobbyist for about 5 years now and my tank pretty much requires no maintenance ... I just do a partial water change and trim back my plants every 2 weeks or so.

Now I'm looking to build a reef tank. I'm looking at a 120 gallon tank and a 20 or 29 gallon sump depending on what I can fit in the stand. Professionally I'm an engineer so I'm going to be building my own sump once I have the details ironed out.

And onto my question, which may seems silly ... the 120 gallon tank I'm looking at buying isn't "reef ready", i.e. it isn't pre-drilled. I'm looking at using a HOB overflow box and a return pump. Do these need to be spec'd at the same flow rate? I was specifically looking at the CPR CS90 Overflow Box (600 GPH) and the Sicce Syncra Silent 2.0 Multifunction Aquarium Pump (568 GPH). Will the difference in flow rate cause me problems and if so, is there a HOB overflow box and return pump anyone can recommend to be used together?

Thanks!


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## rayray74 (Mar 19, 2013)

the overflow rating means it can handle 600 gph
it will only drain what the pump puts through it.
my overflows will handle 2000 gph
my pump is 1800 - then factor in head height and elbows its really about 800.


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## ShaySpins (Oct 22, 2013)

rayray74 said:


> the overflow rating means it can handle 600 gph
> it will only drain what the pump puts through it.
> my overflows will handle 2000 gph
> my pump is 1800 - then factor in head height and elbows its really about 800.


Thanks! I read somewhere that the flow rate for a reef tank should be 20x the # of gallons. So for a 120 gallon tank that would ideally be 2400 GPH. Is it just me or does that sound like overkill?


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## coralbandit (Jul 29, 2012)

Flow should be between 10-20 times volume,10 is safe.More important is circulation with powerheads or hydors,they can go up to 30 time tank volume.
Make sure you count head pressure into pump flow and basically every 90 elbow equals 
1' of head pressure.
I always build my own sumps or modify/add to an existing type.Enjoy and keep us "posted"!


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## joipaloi (Oct 24, 2013)

First of all, CPR makes some really nice filters that are built with quality. I have been using them since the company started many years ago. As far as twenty times....that is too high. Keep the turnover closer to 10 time or even a bit less if you have plenty of current throughout the tank. As much as I don't like the hang over the back over flow boxes, CPR also makes a nice one of those as well. If the tank is glass then HOB is best option but if it is acrylic consider drilling it and building or purchasing a pre filter box internally. As far as the return pump goes, make sure that it can handle the head pressure. You should always place a valve between the return pump and the aquarium so that you can adjust the amount of water flow and avoid the worry of too much or too little water return. Good luck and enjoy!


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## Reefing Madness (Aug 12, 2011)

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