Return pump size and water flow

[fyretr7]

Hi Guys,
The fun is starting already lol.Anyways I am beginning to collect the things I will need to set this reef tank up right the 1st time.I have a cpl questions I would like some advice on.I visited the local fish shop here and asked what was the best waterflow return rate for my 125 gallon oceanic aquarium.The aquarium is drilled and has a 30 gallon sump/refugium on bottom with 2 return lines.The system was running a mag 18 at the time it was taken down(the mag 18 is toast at this time).The guy also had 2 6080 Tunze power heads for water movement.The guy at the shop told me he believed the mag 18 was a bit overkill for the tank size I had.Adding it all up I would guestimate that total flow was around 6100 gph with the mag 18 so should be around 5580 with the mag 12 .What are ur guys opinions.I noticed on the canopy he had alot of splashover in the front and some on the sides.I am in the process of removing the bad laminate and am going to line the underside of canopy with formica.
The other question I have is about lighting to start out with.LIke I stated in the other response I got the canopy with 4 vho bulbs and 3 Metal Halides/w ballast.My question is this.Since I am starting out with a few softies,reef safe fish,and anemones do you think it is necessary to actually run the M/H lights or will the other be sufficient to get started with.I plan on trying to "jump-start" my cycle on this tank with Water from my other two aquariums when I do a half water change.I will have around 110# of live rock,Im thinking maybe a 3 or 4" medium grained live sand bed,and placing a small layer of active sand and live rock rubble in my sump,along with the usual "clean-up crew of snails,hermits,and shrimp.I would like to actually adda cpl emerald or sally lighfoot crabs to the tank but am also considering moving "Walter" my 2' snowflake eel to the larger tank, he is in a 40 gallon tank now with fish & Live rock.I know in wild eels are "crab eaters" but I keep him well fed.Any advice U guys could give would be appreciated .............Thanks in advance

 

[ZOOT098]

IMHO i would go with a mag 9.5
you should be running about 3 to 4x your display tank volume through your sump per hour, and make up the rest of the flow with powerheads or a closed loop system, otherwise you will have microbubble problems, and the water will be moving so fast through the sump that your skimmer wont be able to do its job

I just went through this same thing, i was running a mag 18 and a mag 9.5 at the same time, my sump looked like you could white water raft in it

 

[ccCapt]

Average flow rate thru a sump should be aprox 5-10 times the tanks water volume. You can see this in a new "Reef Ready" predrilled tank. A 75/90g tank has 1 1" overflow. A 1" overflow can handle 600 gph. A 120/125g has 2 1" overflows for 1200 gph total.
What size are your overflows? If they are standard 1", base the pump you choose on that rating.
2 Tunze 6080's are not overkill. :)

If you want to keep an anemone, you should use the MH's.

 

[winyfrog]

i agree with cccapt.

 

[fyretr7]

Okay let me see if I understand this right.If my tank has 2 1" overflows,then a 1200 gph pump would be the right "maximum" size at the "higher"end of the flow ratings.I think my return has a crossover in it.Based on the 1st response I am thinking my pump is too big to handle what I have,but if you take the mag12 and figure in the friction loss for the crossover and the rise I should be pumping appr. 900 gallons on the return if I have figured this out correctly.Most everyone I have talked to so far here has said to go with the 12.I guess I could put a gated ball valve on the outlet side of the pump and gate my flow down some if needed.I don't have much experience with the mag pumps but I know when U begin gating down centrifugal pumps there is some chatter involved.Wondering if the mag 12 would be affected in the same way?Honestly from what I have heard so far I'm seriously thinkng of usung the 12 as a backup and just getting a mag 9.5 as my primary pump,does that sound feasable or should I just leave it as is and see what happens.Again Thanks guys,this is so confusing.I mean I know Hydraulics and friction loss,etc but I wanna do this right and picking u guys brains helps so much........................Doyle

 

[project5k]

so, if your worried about pinching off the flow on the crentifugual pump, then why not build yourself a bypass valve system? i'll draw a picture in a couple min...

so, this way, the pump moves its maximum flow rate all the time, but you get to control how much of that water makes it up to the tank. the more that you open the valve, the more water is just recirculated in the sump, close the valve some, and more water goes up to the tank. heck, depending on how things work out for ya, you could use this bypass water for the flow in your fuge(if your fuge isnt already inline with the rest of the sump flow)

this should reduce the chatter issues you're talking about.

oh, and just fyi, the word your looking for for the losses in the system, lifting the water up to a height, and the friction and what not, thats all called "head"

 

[fyretr7]

Oh guys BTW not sure if I said this already but my friend who had the tank before me was running a mag 18 with this very same set-up.Supposedly(not sure how true it is or isn't)a saltwater aquarium expert set this tank up for his dad.The guy even built his own skimmer and the sump area is a converted aquarium with acrylic panels and grating installed.Its not a huge sump not sure how much water flow it would handle.It is big enough to house a huge DIY protein skimmer and pump in the middle.I am on a 48 so I can't see the tank configuration and truethfully I dont remember exactlly how the return is piped.I was planning on re-plumbing some of the lines to make room to build some shelves for ballast and supplies on either side.If I do that I can kinda pipe it to lessen somewhat the friction loss and maybe go with a lower head pressure pump.Lol will save wattage to up my metal hallides usage...........................Doyle

 

[project5k]

the best way to reduce friction is to reduce the number of degrees of turns in the flow path, and reduce the sevarity of each turn, make 2 45's rather than one 90, that kinda thing, but over all shorter length, larger diameter, and fewer turns are the ways to reduce losses.

 

[yote]

Just hook that Mag 12 up.Thats what I'm running on 125 and it seems just about right for flow through the sump.
Also be careful about having the ballast in the stand.Those ballast can produce quiet a bit of heat in a confined space.

 

[Melosu58]

I run a mag 12 and a mag 9.5 on my 125.

 

[yote]

I run a mag 12 and a mag 9.5 on my 125.

One on each return?
I hadnt thought of that :D But will remember it if and when I upgrade again:bounce:

 

[dcantucson]

I run two Quiet One 14000 pumps (3500 gallons each) on my system's two returns, but I have no power heads.

 

[ZOOT098]

from melev's reef:

So how does it work specifically?

Water drains from the display tank into the sump container beneath. The water is pushed back up to the tank with a "return" pump, which is either submerged in the sump or run externally (which involves bulkheads and plumbing, but avoids adding as much heat to the water). As the water rises slowly in the display tank, it flows into the overflow box (or chamber), and this drains back into the sump. It is a constant cycle, and the goal is to pump as much as the tank can drain. Most people aim for 10 to 15 times the volume of the tank for total circulation. The sump's return flow would be a portion of that total circulation, maybe 3 to 5 times the total circulation, and the rest is provided with powerheads and/or a closed loop system.