Water circulation rate i.e. sizing of return pump

[UB400]

Sorry to ask a basic question. I intend to have a sump where I will house a Skimmer, Calc Reactor etc. each with their own pumps that will be sucking in water from the Sump and releasing the effluent back into the sump.

I'm trying to determine what size of pump I need to put in the sump to return water to the DT. I will have a 125 Gallon DT, haven't determined the size of the sump yet and was wondering typically what number of circulations i.e. DT to Sump to DT, should one aim for?

Also any recommendations of size of sump, I haven't decided yet but may want to add a fuge as well.

Thank you for your advice, it will be most appreciated.

 

[ReeferBob]

I have a 125 with dual overflows and have an Eheim 1262 (910gph) for the return and a 40B for the sump. I also run a media reactor with it but it gets just a trickle. I should have got the 1260 (640gph)I have to dial back the 1262 quite a bit as it is too much flow.

 

[UB400]

Thanks ReeferBob, that's the kind of info I was looking for, much appreciated. If I may ask, what's the Head on your return line i.e. height, number of elbows etc. ? I plan on using a flexible hose as the return to minimize the Head on the return.

 

[Mike J.]

My experience is similar. I had a Mag 9.5 on my 120 and downsized it to a Mag 7. It has a hose on it and a ball valve, but I don't believe in restricting the flow because of added stress to the pump. Also have two Voyager 4 on a Koralia Smart wave, so plenty of flow in the tank.

 

[UB400]

Thanks Mike, I really appreciate the advice. It sounds like a win win to me, smaller pump, less electricity and I can also save some money and buy a backup pump if needed.

 

[Reefing Madness]

One should aim for 5-6x your DT water volume through the sump. Then you want to have your return pump come as close to that overflow number you can get it, without going over that gph. Now you can go over it, providing you T off the return line back to the sump using a ball valve to fine tune the return flow. You'll need to look for a pumps GPH after the head loss of your system. Most are 4-5' head loss. You'll also need to drill a couple holes in the return pvc just under the water line to act as siphon breaks, incase of poewr loss. This will make sure you don't back siphon your DT into the Sump.
Heres a good read on Sumps:
Melevsreef.com | Acrylic Sumps & Refugiums

 

[AZDesertRat]

3 to 5x the display volume is a very common size, I err on the larger end myself so 5-6x is good after headloss. You will want to go a little larger than install a valve in the discharge to fine tune the flow to match the overflow.
It also depends on the size of your sump. If the sump is small, 10-15 gallons, that size pump may be too much and cause high velocities in teh sump carrying microbubbles back to the display. If the sump is 20-30 gallons or larger the 5x is great on a 75G display as it will allow water to pass through the sump at a good rate.

Never depend on drilled holes or check valves in the retrun, both are a flase sense of security, require maintenance and will fail, not if but when. The only foolproof method of backflow prevention is an air gap, we all know water cannot jump uphill so keep the returns close to the surface and when a slight, easily calculated amount of water flows back the return is exposed tp atmosphere and the siphon breaks. no cleaning, no maintanance amd its impossible to defeat. A common dimension for a 75G is 48" long by 18" front to back. An inch in depth siphoned back to the sump is only 3.7 gallons so keep the returns no more than an inch below the surface and maintain 3.7 gallons or more spare room in the sump and you are good. It can't possibly overflow or flood and you will have more room than that anyway as skimmers and equipment only need 8-9" submergence to work best.

Never return flow back to the sump. This requires more work from the pump, creates more heat and noise and draws more power. Always place a ball or gate valve in the return to the display and throttle the pump in that way. It is easier on the pump since it is pumping less, doing less work so less power is consumed, less heat is created and its much quieter. Centrifugal pumps only do the work required of them plus a little for inefficiencies so returning water to the sump via a tee and valve is more work than slowing the return to the display. It sounds crazy but is true.

 

[bucksfan1976]

I have a 92 corner and I have a Mag 18, but what i did was make it run everything, it runs as my return to my tank and it runs 2 reactors, I just run ball valves going to each to control flow. Its better to be bigger then not have enough flow, plus I like the Idea of a single pump compared to multiple pumps.

 

[ReeferBob]

It is around 5 feet total from pump to return. I have 4 90s and a gate valve on each side (coming from a manifold). 3/4" plumbing with dual loc-line outputs for each return.

 

[UB400]

Thank you everyone for the advice, I really appreciate it. There is no substitute for experience and I'm definitely learning from the wisdom here. Another question, I was planning on making one overflow corner which will have a total of three pipes, two drains (one as an emergency) and a pipe for the return. The idea was to reduce the amount of "real estate" taken up by Overflows and simplify plumbing. Will this be okay, or should I move the return to somewhere else. All the pipes will be at different heights of course, taking on board AZDesertRat's suggestion for the return.

 

[AZDesertRat]

It depends on how big the overflow box is, three drilled holes in one box with enough room between them for glass strength and to be able to turn the bulkhead nuts takes up a lot of room.
I have a single 1" overflow in my 100G and in 9 years have never once had any problems with flooding or outrunning its capacity. Everyone seems to be on the dual overflow kick nowdays but I have never found it necessary as long as you take the time to design your overflow, standpipe and plumbing correctly in the beginning.

I originally had my retrun drilled up through the bottom inside the overflow box but found it limited my return possibilities. I started with a LocLine wye and two 3/4" nozzles but it still did not return like I wanted so I abandoned that return and used drilled holes in the two upper back corners I originally had for a closed loop. I axed the closed loop and the 63 watts of power it drew to move 900-100 GPH and now use two Evo 1400 powerheads at 4.5 measured watts apiece to move 2800 GPH. The return now exits those two holes again with LocLine but through an Oceans Motions Squirt two way so I get lots of random flows in the display with a single return pump and the two Evos.

If you are just designing the tank I would include two holes inside the overflow box and one hole each in each upper back corner. The two in the overflow could be an overflow and return or it could be your overflow and the back up you talked about. Its nice to have options and a drilled hole can always have a plug screwed into the threaded bulkhead for future.

 

[UB400]

Thanks AZDesertRat, The Overflow box will be 6" x 12". The drain pipes will be 1.5", while the return will be 1.25". I was hoping to keep the three holes at the bottom, so that I could keep the back wall of the tank close to the wall, I'm working with a real small space to squeeze in as big a tank as I can. I plan on having a 2-3 power heads in the tank for the internal circulation. In my mind, the purpose of the return is mainly to bring back the water from the sump.

 

[AZDesertRat]

1.5" bulkheads require a 2 3/8" hole so the nut is probably at least 3.5 to 3.75" outside diameter if not more so you would need about 4" clearance for each plus stay at least 1/2 the bulkhead diameter away from the back or sides when drilling. Three of those will take a lot of room I'm not sure you have in this case. My internal overflow box is about the same size and once they centered two 1" bulkheads inside it there wasn't a lot of clearance for plumbing inside or out.
I can just about guaranteed you, placing the tank close to a wall will eventually lead to problems. eithe rwith clearance for one reason or another but also with drywall and paint coverings. My old 20G reef was in the same location for many years and when I sold it to tile the floors in the house I had to remove and replace some drywall that had bubbled behind and beside the tank that wasn't really visible until the tank was moved. I would leave it at least 9-12" away from the wall as some time or another you will need to get behind it to fish something through, clean the back etc.

Yes the return isn't really counted as major flow but in my case with the Squirt I was able to take advantage of that random flow without any added pumps or expense. I'm glad I had the back drilled and still have two spare holes, one in the back center which was the original closed loop suction and one in the overflow box which was teh original return location. The returns in the back corners only extend about 4" behind the bulkheads which have a 90 degree elbow and ball valve on them so they can be isolated or throttled then go into 1" braided reinforced vinyl tubing which is quieter and smoother flow than all PVC.

 

[UB400]

AZDesertRat, I hear you loud and clear. This is just the kind of feedback I was hoping to get. I was planning to cover the Concrete wall behind the Aquarium with either Acrylic or similar plastic, it will extend to about 12" higher than the Aquarium, I was hoping to to use this as a "Splashguard" that would hopefully prevent some of the problems you mentioned. I was planning for a gap at the back of about 2" or so, just in case as you mentioned.

By the way, I'm planning on using an Acrylic Aquarium and the walls will be 15mm thick, but regardless I'm taking on board what you're saying and will revise accordingly. I know sound advice when I see it, thanks you have saved me a whole lot of head ache.

 

[AZDesertRat]

Thats what these forums are for. Get as many opinions and experiences as you can and make your choice. I incorporated a lot of advice into my current builds and it saved me a lot of headaches and expense in doing so. I was lucky to be a member of a very active club at the time and that helped too, being able to visit others homes and tanks gave me a ton of ideas to work with.

 

[ReeferBob]

Oh are the holes not drilled already? I would bet that the bottom of your tank is tempered and cannot be drilled! Make sure you check before you start drilling!

 

[UB400]

Hi ReeferBob, It's going to be Acrylic 15mm walls.

 

[mcarroll]

2-4x display volume as your sump throughput is all you need. (2x usually will do it 4x allows for aging equipment and declining conditions in the plumbing. The same throughput rate should be great as the throughput of your prospective skimmer as well.

Overkill is not uncommon as you see by recommendations (and a few you see that have back-peddled on their over-size pumps) but you aren't really buying yourself any advantage going that route.

Figure out a good estimate of the head your pump will be working with and choose a right-sized pump. You won't look back.

-Matt


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[UB400]

Thanks mcarroll, much appreciated, advice taken on board. I'm all for "right sizing".