overflow size?

So, I am helping my father install a basement sump for his 46g bowfront using a 40g breeder and I have a few questions:

How do you figure out how big of an overflow to use? We found an overflow that does 500gph - is this too much?

Also, I used a head loss calculator to try to figure out which pump for him to use and was thinking of using the blueline hd55. It is 1190 gph with max 28ft of head. According to the calculator it would be putting out a little over 700gph given is configuration, so I figured we could use a valve to backk it off a bit to match the overflow. Does this sound on track or is this too much flow?

Also, is it bad for the pump to have it backed constantly backed off by using a ball valve? Sorry for all the questions.

TIA

 

Will this be a reef or a FO setup?

Since the drain rate is controlled by the return pump rate, I'd go with a higher rated overflow...there's no sense in valving the pump back that much if you don't have to, esp. since this is a new build.

That being said, I generally run a "bleed valve" back to the sump on my returns. If the pump is hotter than I need, or if I'm having trouble getting "max quiet" via standpipe venting, I can dial it in via the valve.

Here's a quick sketch (it works the same with an external pump):

 

Returning flow back to the sump is an extremely inefficient way to control flow. It uses more power, creates more heat and is noisier than simply installing a valve on the discharge side of the pump and throttling the flow. Restricting or throttling the return flow makes the pumps work less so it draws less wattage, thus creates less heat to transfer to the water and is quieter in operation. Why pump water and consume energy only to return it to the sump with no benefits?

 

Thanks for the pic Greg. I saw something like this on another site and was considering it. So your saing to try to get a 700gph overflow and redirect the rest of the flow to the sump... That may work as he may set up a refugium down the road and that flow could be directed there. Do they make overflows that are 700 gph?

 

So this doesn't hurt the pump?

 

http://www.3reef.com/forums/i-made/non-drilled-tank-alternatives-my-diy-overflow-140523.html


You could get some easy, cheap OF ideas from
One on my thread.

 

Wow! That looks great! I may have to try this!! We are doing this for my dad's 46g and I am doing a basement sump for my 125 in my house.

 

My system is on a non drilled 125!
If you would like to customize an OF and sump for your set up, I can certainly help.
It can and will be very inexspensive!
These items are NOT hard to build and take no special skills.
It can and will be safe-as in no wet floors/flloods
and Work WAY better than stroe bought overflows and or sumps.

The possibilities for the sujmp design are endless, etc.

Please PM me if you like as well, as I don't want to initially PM you regarding this- I don't want to seem to 'pushy'.

Mine's been working excellent for over a year now. Lots of variations to the DIY world regarding this.

My sig has short vids of my DIY overflow; DIY sump; and a brief tour of my 125reef.

 

Throttling, restricting or valving the flow of a centrifugal pump often makes them more efficienct and in no way harms them, quite the opposite in fact. Study Bernoulis Theory and the Laws of Affinity to learn why. This is a very misunderstood thing and often done incorrectly, never return flow to the sump when it is harder on the pump, costs more in power, creates more heat since the pump is working harder and is a waste of energy.