Circulation-Closed Loop

[Reefres]

I'm in the process of setting up a 120 AGA RR with Twin Mega Flows. I initially was not going to incorporate a Closed Loop but after reading many threads have changed my mind. This is where I need input, I have listed my proposed set up and some questions. Would appreciate any and all feed back.

Sump Return Pump: MD40RLXT
Return through chiller and split to feed 2 3/4" returns in overflows.
"T" with ball valve to feed refugium located above tank.

Closed Loop Pump: MD70RLT??
Drill for 2" Intake - 6" below WL centered between overflows.
Return split to feed 2 3/4" Seaswirls in front corners.

Will this be enough circulation and water movement for mixed reef SPS and softies?

Will this set up create enough flow near the bottom of the tank so there is no dead spots or should I look to add additional drilled returns for the CL near the bottom? Additional intakes needed? If so where as there is only 6" from the side of the tank to the overflows on the back wall. How close to the edge can you drill the tank?

Sorry for all the questions just trying to get it right the first time.

Thanks for all the help.

 

[ChrisRD]

So far your setup sounds great - sounds like you've done your homework.

IMO the 70RLT would not be a very energy efficient choice for a closed loop. I would prefer to use a high flow, low head (ie. non-pressure) type design - probably a Sequence. A lot of people like Ampmasters too. Those types of pumps move a ton of water while consuming reasonable amounts of electricity.

With a pump like that you'd have so much flow you could afford to put those extra bulkheads in the back of the tank and split off to them (as well as feeding the two SSs up front).

Check out the pump guide in our library - might help.

 

[ChrisRD]

BTW, you might get more feedback to this from people who've tried something similar in the GRD forum so I'll move this over (and leave a copy in the NRF as well...)

HTH

 

[Reefres]

If I were to add 3 returns approx. 10" off the bottom of the tank (1 near each corner and 1 center) and also feed the 2 3/4" Sea Swirls which model pump do you think would be best from Sequence or Ampmaster? Do you want to match the size of the inlet on the pump to bulkhead fitting in the tank or would you oversize the bulkhead in the tank? Having not run a CL before will I need to worry about fish/etc being sucked to the screen in the tank with a larger pump like reccomended. What size would you recommend the returns 1/2" or 3/4"? Thanks for all the help.

 

[ChrisRD]

If I were to add 3 returns approx. 10" off the bottom of the tank (1 near each corner and 1 center) and also feed the 2 3/4" Sea Swirls which model pump do you think would be best from Sequence or Ampmaster?

Personally I'd look into using one of these three pumps:

http://www.mdminc.com/Sequence_750.htm

http://www.mdminc.com/Cimarron.htm

Do you want to match the size of the inlet on the pump to bulkhead fitting in the tank or would you oversize the bulkhead in the tank? Having not run a CL before will I need to worry about fish/etc being sucked to the screen in the tank with a larger pump like reccomended.

Considering the inlet on the pump is already 2" I'd just stick with that. If you're concerned about suction forces you can either drill for two bulkheads/intakes (and just plumb them together outside the tank), or use a tee or 4-way fitting inside the tank with intake screens on each opening. Which method I would choose would depend on how I was going to aquascape the tank (I'd want to hide that stuff). Just be sure to leave the intakes reasonably accessible for future maintenance.

What size would you recommend the returns 1/2" or 3/4"?

I'd stick with 3/4". I think you'll be seeing fairly high velocities out of 1/2" outlets with that much flow.

 

[Reefres]

Thanks for all the great information. I was thinking the 750 3600SEQ12 would work great and should have plenty of flow as it will sit directly behind the intakes and will have only 1' of head pressure to reach the Sea Swirls and will drop down to reach the drilled returns.

I will probably drill a second intake in the same area as I plan to keep that open for easy maintenance of the stainers. Thanks again.

 

[ChrisRD]

Sounds like a good choice for the pump and a very nice setup.

Keep in mind you won't have any gravity head to overcome in a closed-loop setup regardless of where the pump is placed. The only resistance will be friction/form losses due to the water flowing through the pipes/fittings.

Placing the pump so that there is minimal plumbing will help reduce losses in the sense that they'll be less pipe and fittings to travel through, but not because there will be any gravity head. Also, using larger diameter plumbing to the extent possible will help minimize the losses too.

HTH

 

[Anonymous]

FWIW, I am using 2 separate Iwaki 40XRLT pumps on closed loops for my 360. Each pump is fed my a separate 1.5" drain bulkhead in the bottom of my overflow box (I use Dursos for the other drain bulkheads to maintain a high water level well within the chanmber). The water is returned via a 1" SeaSwirl in each front corner of the tank. I like this set-up very much.

I have heard that the MD70 is loud, but I could be mistaken. If this is true, then you may want to consider using 2 separate 30RXLT pumps instead for your closed loops. This may also simplify your plumbing, besides giving you redundancy.

FWIW, I am using a Sequence 4600 for my sump return pump.