Closed loop?

Hockey0000325 · 10/14/2009, 08:28 PM

Hey guys,

I have a 120 gallon Reef tank with a built in overflow in one corner and 2 other drilled holes for a closed loop. Or so I am told. I would be very intersted in setting this up properly so I would not need powerheads and use the closed loop. I am just confused on a few things. I obviously have to have 3 lines feeding the sump and 3 in return but being that the pump in the sump has only 1 return line what would be the best way to set this up. I plan on running flex tube for my overflows and my returns as i have my sump directly underneath the stand and have a mag 5 for my return pump. I have been told i will get enough flow from this type of setup to not need powerheads. I was also told that there is a gentleman by the name of Kent who has made this tank. And he is a reef guru around the Rochester area. Any advice is greatly appreciated!

xcdennisx · 10/14/2009, 10:43 PM

go to lowes or homedepot and get pvc connectors it would go from one to three or how many return holes you have in your tank. im not sure how much flow that pump has but you would want at least 10x you tank for flow

dots · 10/14/2009, 11:33 PM

Ask whom you bought it from if they have a picture or a diagram of the previous configuration.

dots · 10/14/2009, 11:53 PM

Let me see if I can suggest more for you:

Closed loops tradionally take the water out of the back, plumbed down to an external pump like a Dart for example, and the pumped back in. Flow in = Flow out, and because the diameters are the same and the holes are at the same elevation losses to gravity and what the pump must produced to overcome it are cancelled. Because it is not open to the air....it is a "closed system". If the pump goes off the water level is not effected.

Therefore, use the overflow as an independent sump flow circuit with a pump that provide about 5X the size of the tank per hour.....this is typical.

So you might have noticed with just two holes....one in and one out.....it gets a little boring flow wise and isn't very turbulent.

As seen here:
http://www.reefcentral.com/forums/sh....php?t=1702095

Most use the two big ones as outlets to feed the pump(s), after the water exits the pump, it is broken down in more returns, but at a smaller diameter.

Realizing the following definitions:

Flow=Area*Velocity or Q=AV

Flow in equals flow out or Qin=Qout

You can begin to see how the design is calculated.

By splitting it up into multiple smaller returns, it creates a much more dynamic and dispersed flow as opposed to the "in and out" type. Combine this with a valving actuator (OM squirt) it is even more dynamic as flow is chambered into only certain returns at a given time.

Do your homework, and the math first before you go out and buy a single thing because notice I didn't mention on what pump you needed. This is based on what you plan to keep in the system. A estimate on what you need is 30X for a non SPS tank, and 60X or more with SPS only. (roughly speaking) So take that five off from your sump....giving you a flow of around 120*25 or 120*55 in gallons per hour......because of the distances involved and it goes up and down in about the same place your looking roughly for a pump that flows near those two numbers at 0 TDH.

Quick and dirty.......this explation is to get you pointed in a direction.

dots · 10/14/2009, 11:55 PM

http://www.reefcentral.com/forums/sh....php?t=1663066

Some other possible references.

IslandCrow · 10/15/2009, 08:46 AM

Here are a couple more links to closed loop designs on Melev's site, which if you haven't visited yet is a treasure trove of information, especially for DIY projects. Melev uses a device called a SCWD in his design, which is a great idea, but not necessary. His design also uses a U-tube to gavity feed the water via siphon from the main tank to the pump. Since you only have two holes drilled in the back of your tank, I'd use this basic design so both of your drilled holes can be used for returns.

In general, closed loops are really quite simple. As stated, water gets fed via gravity from the main tank into an external pump and then gets pumped right back where it came. It doesn't go through the sump and is completely self contained. Its only real purpose is to provide water flow, so use the head loss calculator (there's a link on the Reef Central homepage) and choose a pump that will give you the flow that you need. Anyway, here's the additional reading material:

http://melevsreef.com/how_to_build.html

http://melevsreef.com/closedloop(old).html

Hockey0000325 · 10/15/2009, 11:42 AM

Thank yuou all So much for clarifying this for me. It makes much more sense now that I understand exactly how the closed loop works. I for some strange reason thought it was sent to a sump before return. now that i realize it is just a loop to a seperate pump i get it. Thanks for all the threads you guys are always very helpful

10/14/2009, 08:28 PM	#1
Hockey0000325 Registered Member Join Date: Sep 2009 Location: Rochester Posts: 268	Closed loop? Hey guys, I have a 120 gallon Reef tank with a built in overflow in one corner and 2 other drilled holes for a closed loop. Or so I am told. I would be very intersted in setting this up properly so I would not need powerheads and use the closed loop. I am just confused on a few things. I obviously have to have 3 lines feeding the sump and 3 in return but being that the pump in the sump has only 1 return line what would be the best way to set this up. I plan on running flex tube for my overflows and my returns as i have my sump directly underneath the stand and have a mag 5 for my return pump. I have been told i will get enough flow from this type of setup to not need powerheads. I was also told that there is a gentleman by the name of Kent who has made this tank. And he is a reef guru around the Rochester area. Any advice is greatly appreciated!

10/14/2009, 11:33 PM	#3
dots Registered Member Join Date: Nov 2004 Location: Sacramento, CA Posts: 6,258	Ask whom you bought it from if they have a picture or a diagram of the previous configuration. __________________ ~Doug

10/14/2009, 11:53 PM	#4
dots Registered Member Join Date: Nov 2004 Location: Sacramento, CA Posts: 6,258	Let me see if I can suggest more for you: Closed loops tradionally take the water out of the back, plumbed down to an external pump like a Dart for example, and the pumped back in. Flow in = Flow out, and because the diameters are the same and the holes are at the same elevation losses to gravity and what the pump must produced to overcome it are cancelled. Because it is not open to the air....it is a "closed system". If the pump goes off the water level is not effected. Therefore, use the overflow as an independent sump flow circuit with a pump that provide about 5X the size of the tank per hour.....this is typical. So you might have noticed with just two holes....one in and one out.....it gets a little boring flow wise and isn't very turbulent. As seen here: http://www.reefcentral.com/forums/sh....php?t=1702095 Most use the two big ones as outlets to feed the pump(s), after the water exits the pump, it is broken down in more returns, but at a smaller diameter. Realizing the following definitions: Flow=AreaVelocity or Q=AV Flow in equals flow out or Qin=Qout You can begin to see how the design is calculated. By splitting it up into multiple smaller returns, it creates a much more dynamic and dispersed flow as opposed to the "in and out" type. Combine this with a valving actuator (OM squirt) it is even more dynamic as flow is chambered into only certain returns at a given time. Do your homework, and the math first before you go out and buy a single thing because notice I didn't mention on what pump you needed. This is based on what you plan to keep in the system. A estimate on what you need is 30X for a non SPS tank, and 60X or more with SPS only. (roughly speaking) So take that five off from your sump....giving you a flow of around 12025 or 12055 in gallons per hour......because of the distances involved and it goes up and down in about the same place your looking roughly for a pump that flows near those two numbers at 0 TDH. Quick and dirty.......this explation is to get you pointed in a direction. __________________ ~Doug Last edited by dots; 10/15/2009 at 12:01 AM.*

10/14/2009, 11:55 PM	#5
dots Registered Member Join Date: Nov 2004 Location: Sacramento, CA Posts: 6,258	http://www.reefcentral.com/forums/sh....php?t=1663066 Some other possible references. __________________ ~Doug

10/15/2009, 08:46 AM	#6
IslandCrow Reef Monkey Join Date: Sep 2005 Location: Rockledge, Fl Posts: 5,759	Here are a couple more links to closed loop designs on Melev's site, which if you haven't visited yet is a treasure trove of information, especially for DIY projects. Melev uses a device called a SCWD in his design, which is a great idea, but not necessary. His design also uses a U-tube to gavity feed the water via siphon from the main tank to the pump. Since you only have two holes drilled in the back of your tank, I'd use this basic design so both of your drilled holes can be used for returns. In general, closed loops are really quite simple. As stated, water gets fed via gravity from the main tank into an external pump and then gets pumped right back where it came. It doesn't go through the sump and is completely self contained. Its only real purpose is to provide water flow, so use the head loss calculator (there's a link on the Reef Central homepage) and choose a pump that will give you the flow that you need. Anyway, here's the additional reading material: http://melevsreef.com/how_to_build.html http://melevsreef.com/closedloop(old).html __________________ All opinions in the above message should be taken with 35 ppt salt. -Mike C. Current Tank Info: I have a reef screen saver on my phone, does that count?

10/14/2009, 10:43 PM	#2
xcdennisx Registered Member Join Date: Oct 2009 Posts: 50	go to lowes or homedepot and get pvc connectors it would go from one to three or how many return holes you have in your tank. im not sure how much flow that pump has but you would want at least 10x you tank for flow

10/15/2009, 11:42 AM	#7
Hockey0000325 Registered Member Join Date: Sep 2009 Location: Rochester Posts: 268	Thank yuou all So much for clarifying this for me. It makes much more sense now that I understand exactly how the closed loop works. I for some strange reason thought it was sent to a sump before return. now that i realize it is just a loop to a seperate pump i get it. Thanks for all the threads you guys are always very helpful