how many GPH for return pump - NEW question please read post #39

Heat isn't a problem at all with my tank. If anything extra heat is just making the heater cut on less. The power difference isn't that great from getting 2 smaller pumps and I prefer 2 pumps because if one pump goes (especially while I'm out of town), my water volume isn't cut in half and algae won't want to start growing in the display. Also, I prefer not seeing a powerhead (or any other equipment) if possible.

 

I am guessing the corner overflow is drilled with two 1" bulkhead holes or a 1" for the overflow and a 3/4" for the return which is pretty common in the industry. If so it should easily bea able to handle 350-500 GPH with the proper standpipe design.

 

this is their response to my inquiry via email:

Thank you for contacting Deep Blue Professional. Our drainpipe is rated up to 600-GPH, and we suggest using a return pump that can output at least 600-GPH at seven feet of head pressure. Hope this helps!



If you have additional questions or concerns, please do not hesitate to contact us again.
Thank you for choosing Deep Blue Professional.

DBP Customer Service

So that's the size return pump I need correct?

 

Thats a lot of pump for a 65G return and I seriously doubt you will have 7 feet of head unless you have a basement sump, very small diameter plumbing or lots of elbows and restrictions in the return. At the more common 4-5 feet of head that pump would probably be more like 800-900 GPH and would outrun the overflow if it is rated for 600 GPH.
I would stay around 5+/- times the display volume at whatever you actual head will be.

 

ok, my head will be 4.6 feet if I did the math right. So should stay in the range of 350-400 - is that correct?

 

A general rule of thumb often cited is 3-5x the display volume after headloss for the return and make up any other circulation with more efficient powerheads etc.
I err on the high side myself so 5+ times display volume would be my choice with a decent sized sump volume which I think you will have. Some will say bump it up but thats when the sump design becomes really important as it is easy to get microbubbles back to the display or not have sufficient time in the sump for the protein skimmer to work efficiently. 5x is a pretty safe number. I always go slightly larger on the pump, not way oversized but a little, as it is easy to install a ball valve on the discharge to fine tune GPH and gives you the option to plumb a manifold for reactors etc. Say get a pump capable of 7x the display volume and so on.

 

As stated earlier, you could go larger and put a valve on the RETURN (line back to the DT) and throttle the flow back a bit. This actually helps the efficiency of the pump. NEVER restrict the flow to the pump or sump area.

 

I'm with AZ...I pretty much always "overpump" our DT's by a bit, as one never knows really how much head, friction, etc. is in the system. Plus, if you ever decide to add a chiller, reactor, etc, you won't have to repump the system...just open up the valve.

Also, I recommend installing the pump using true-union ball valves, in case you eve need to remove the pump for servicing.

 

extra true union valves. lol

 

All of my pumps have a short piece of vinyl tubing directly off the pump discharge to break up vibrations and noise inherent with solid piping. After the foot or so of tubing it goes to a union and ball valve or tru union ball valve for maintenance and throttling of flows. The flexible tubing is also more forgiving than hard piping when it comes to misalignments since it relieves the stress on fittings and especially bulkheads and water flows quieter through the reinforced vinyl tubing and its smooth bends and transitions than it does through 90 degree elbows and fittings. One thing I do recommend though when using tubing is to step up one size or more in inside diameter to account for and reduce the effects of the restrictions cause by barbed nipples inside diameter. A 1" barbed nipple may only be 3/4" inside so I step up to 1.25" or 1.5" tubing and nipples so the barbed nipple ID is larger and not a headloss issue. Almost all pump manufacturers recommend increasing the pipe size anyway regardless if its PVC or tubing to reduce headloss and increase pump efficiency.