How does it work? Vol 3: Closed loop
- Thread starter Moe_K
- Start date
NateHanson
Non-member
Water movement in the tank is achieved by three general means:
-Powerheads are submersible pumps inside the display tank that suck water from the surrounding water, and expel it without removing it from the tank.
-Return pumps are submersible or external pumps that push water up from a sump tank below the display. Water continually overflows back down into the sump at the same rate that the return pump is returning it. This system is a sort of "Open Loop" because the water is not contained within the plumbing for the entire trip from leaving the display to returning to it.
-Closed loop pumps are (usually) external pumps that suck water out of, and expel water into the same display tank. Water is removed from the tank before being pumped back in, but the water is contained in the plumbing for the entire trip, only one water level is involved, and the pump does not work against any head pressure (as a return pump does), so more of the pump's energy is used to create water movement for your corals.
-Powerheads are submersible pumps inside the display tank that suck water from the surrounding water, and expel it without removing it from the tank.
-Return pumps are submersible or external pumps that push water up from a sump tank below the display. Water continually overflows back down into the sump at the same rate that the return pump is returning it. This system is a sort of "Open Loop" because the water is not contained within the plumbing for the entire trip from leaving the display to returning to it.
-Closed loop pumps are (usually) external pumps that suck water out of, and expel water into the same display tank. Water is removed from the tank before being pumped back in, but the water is contained in the plumbing for the entire trip, only one water level is involved, and the pump does not work against any head pressure (as a return pump does), so more of the pump's energy is used to create water movement for your corals.
Last edited:
Nikkoli110
Non-member
Wooohooo!!!!!!!
I really would like more infotmation on this subject (pics of plumbing too!) Very happy to see this thread!
I really would like more infotmation on this subject (pics of plumbing too!) Very happy to see this thread!
nunofs
Non-member
Adding to what Nate said above, another characteristic of a closed-loop is that there's no risk of backflow/siphoning (namely in case of a power outage) because the intake and returns are all connected to the same body of water. The water will just sit in the pipes until the power is reestablished.
Here's the diagram I used for my plumbing (including closed-loop), and a picture of the finished product:
For clarification, the closed-loop intake is the rightmost/bottom pipe on the pic, the other bulkheads are 4 returns (the top 3 use a loc-line nozzle on the inside of the tank, the bottom/left one uses a spraybar that's hidden behind the rocks to help prevent any dead spots there).
Nuno
Here's the diagram I used for my plumbing (including closed-loop), and a picture of the finished product:
For clarification, the closed-loop intake is the rightmost/bottom pipe on the pic, the other bulkheads are 4 returns (the top 3 use a loc-line nozzle on the inside of the tank, the bottom/left one uses a spraybar that's hidden behind the rocks to help prevent any dead spots there).
Nuno
NateHanson
Non-member
Your tank is as beautiful from the back as it is from the front Nuno! I'm going to let you plumb my next tank!
Jim Tansey
Well-Known Member
Nunofs,
Very nice setup, I enjoy seeing high quality work like that.
Jim
Very nice setup, I enjoy seeing high quality work like that.
Jim
OP
OP
Moe_K
Stabbed by Foulke
We should get a few basics out of the way...
What we're trying to achieve here is water motion. If we were to take a bird's eye view of a real world reef, we'd see intense wave action out where the deep ocean meets the reef. There would be channels cut where the tidal flows rush in and out behind the reefs. Then behind the reef would be a lagoon area with less flow.
How much flow do you need? Well that depends on which type of reef animals you want to keep. Many SPS (stony) corals come from the fore-reef and the intense wave action. Many soft corals come from the lagoon areas. There's no hard and fast rule, and the best way to know where your coral normally lives is to ask questions or pick up reference books like Eric Borneman's or J.E.N. Veron's.
As a unt of measure of flow in our tanks, we talk about gallons per hour (gph) or the number of times the volume of the tank is "turned over." That latter unit sounds more complicated than it really is. Lets say you have a 75 gallon tank, and you have a pump returning water from your sump at a rate of 1100 gph (which is really high). 1100 gph divided by 75 gal = 14.667 times per hour the tank's water volume is theoretically turned over. For SPS coral tanks, we try to keep that turnover number above 12. For LPS or softie tanks, the number need not be so high.
The amount of flow in your tanks adds up. So if your return pump isn't that strong, you can add one of the methods Nate kindly posted above to increase the flow to the desired level.
Any questions?
What we're trying to achieve here is water motion. If we were to take a bird's eye view of a real world reef, we'd see intense wave action out where the deep ocean meets the reef. There would be channels cut where the tidal flows rush in and out behind the reefs. Then behind the reef would be a lagoon area with less flow.
How much flow do you need? Well that depends on which type of reef animals you want to keep. Many SPS (stony) corals come from the fore-reef and the intense wave action. Many soft corals come from the lagoon areas. There's no hard and fast rule, and the best way to know where your coral normally lives is to ask questions or pick up reference books like Eric Borneman's or J.E.N. Veron's.
As a unt of measure of flow in our tanks, we talk about gallons per hour (gph) or the number of times the volume of the tank is "turned over." That latter unit sounds more complicated than it really is. Lets say you have a 75 gallon tank, and you have a pump returning water from your sump at a rate of 1100 gph (which is really high). 1100 gph divided by 75 gal = 14.667 times per hour the tank's water volume is theoretically turned over. For SPS coral tanks, we try to keep that turnover number above 12. For LPS or softie tanks, the number need not be so high.
The amount of flow in your tanks adds up. So if your return pump isn't that strong, you can add one of the methods Nate kindly posted above to increase the flow to the desired level.
Any questions?
Last edited:
nunofs
Non-member
Thanks for the kind words everyone... I did quite a bit of research before doing the plumbing and wanted to share my approach and my results.
I don't want to stray too much from the thread topic, so I'll just say that I didn't drill the tank myself (it was drilled where I bought it, and they used a diamond drill bit), and that I've started with a PanWorld 50PXX-MD30X (1110gph) as my closed-loop pump, and later replaced it with a Velocity T4 (1225gph) just because I needed something quieter.
Btw, the OceansMotion device is a Squirt (the smallest of their products, limited to around 1300gph flow).
Nuno
I don't want to stray too much from the thread topic, so I'll just say that I didn't drill the tank myself (it was drilled where I bought it, and they used a diamond drill bit), and that I've started with a PanWorld 50PXX-MD30X (1110gph) as my closed-loop pump, and later replaced it with a Velocity T4 (1225gph) just because I needed something quieter.
Btw, the OceansMotion device is a Squirt (the smallest of their products, limited to around 1300gph flow).
Nuno
Matt L.
Non-member
Did Someone Say Closed Loops?
Here are some pictures of me constructing my closed loop. This photo shows the two discharge manifolds:
This photo is a close-up of the left discharge manifold:
Regrettably, there are no more decent pictures, as the tank was soon thereafter brought upstairs and put back towards the wall. You can go over the whole closed loop construction in my Reef Central Gallery, along with construction of other key components,
Matt
Here are some pictures of me constructing my closed loop. This photo shows the two discharge manifolds:
This photo is a close-up of the left discharge manifold:
Regrettably, there are no more decent pictures, as the tank was soon thereafter brought upstairs and put back towards the wall. You can go over the whole closed loop construction in my Reef Central Gallery, along with construction of other key components,
Matt
Chuck Spyropulos
Non-member
Clsoed Loop Issues
Closed loop pumps should always be plumbed with true unions at the input and output of the closed loop pump. This makes it easier to take the pump offline for cleaning and/or repair. For large systems, multiple large closed loop pumps may be required along with a mechanism to change the flow to produce random water motion in several directions. This is accomplished by turning one loop off while turning another on and pointing the returns in your tank at opposite ends of your tank and at different, usually opposite, directions.
Closed loops used to be the answer for maximum water motion without the appearance of "ugly powerheads" in your tank. This is their big advantage over other means of creating water motion. However there are a few drawbacks to closed loops:
- If your closed loop pumps are located remotely from your display, closed loops become less efficient. When moving all of that water out of your tank through a relatively long narrow tube to your "fishroom" and then back into the tank, frictional losses through the pipe become noticeable and cut down on the total water movement efficiency.
- Closed loops, alone, cannot efficiently produce the large volume, low velocity flow that is the most effective for coral growth.
Other devices that attempt to produce large volume/low velocity water motion with much better efficiency include dump buckets, waveboxes, Tunze Streams powerheads, etc. .
Closed loop pumps should always be plumbed with true unions at the input and output of the closed loop pump. This makes it easier to take the pump offline for cleaning and/or repair. For large systems, multiple large closed loop pumps may be required along with a mechanism to change the flow to produce random water motion in several directions. This is accomplished by turning one loop off while turning another on and pointing the returns in your tank at opposite ends of your tank and at different, usually opposite, directions.
Closed loops used to be the answer for maximum water motion without the appearance of "ugly powerheads" in your tank. This is their big advantage over other means of creating water motion. However there are a few drawbacks to closed loops:
- If your closed loop pumps are located remotely from your display, closed loops become less efficient. When moving all of that water out of your tank through a relatively long narrow tube to your "fishroom" and then back into the tank, frictional losses through the pipe become noticeable and cut down on the total water movement efficiency.
- Closed loops, alone, cannot efficiently produce the large volume, low velocity flow that is the most effective for coral growth.
Other devices that attempt to produce large volume/low velocity water motion with much better efficiency include dump buckets, waveboxes, Tunze Streams powerheads, etc. .
nunofs
Non-member
The tank doesn't necessarily need to be drilled, here's an example of how to do a closed-loop on an undrilled, running tank: http://melevsreef.com/closedloop.html
In a drilled tank (which is preferable, IMO, if not just for the aesthetics of it) the size of holes is determined by the size of the bulkheads, and the size of the bulkheads and pipes should be determined by the amount of water you'll be moving through the closed-loop... also, different pumps have different intake/output pipe size needs.
Regarding pumps, no need to go with a pressure-rated pump as there's no head pressure in a closed-loop (all losses are due to friction, elbows, etc).
Nuno
In a drilled tank (which is preferable, IMO, if not just for the aesthetics of it) the size of holes is determined by the size of the bulkheads, and the size of the bulkheads and pipes should be determined by the amount of water you'll be moving through the closed-loop... also, different pumps have different intake/output pipe size needs.
Regarding pumps, no need to go with a pressure-rated pump as there's no head pressure in a closed-loop (all losses are due to friction, elbows, etc).
Nuno
Closed loops certainly can produce the large volume, low velocity flow that is the most effective for coral growth. I have one such closed loop in my tank right now doing most of the work. My only other means of water movement are my returns... which are bascially just turning over the water from sump back up to tank. The corals are growing quite well, I would say, and the loop is of the hang-on variety, installed long after my tank was a reasonably established little reef. No drilling necessary... just a little plumbing patience and an efficient water distributor.
I use an Oceans Motions, mounted invisibly at the back/top/center of my tank... powered by an absolutely silent Velocity T4. Same pump Nuno uses.
b
I use an Oceans Motions, mounted invisibly at the back/top/center of my tank... powered by an absolutely silent Velocity T4. Same pump Nuno uses.
b
Matt L.
Non-member
The size of the bulkheads (and number) will depend on what flow you want to achieve.Moe_K said:
When designing my closed loop, I used an old engineer's guideline of a velocity between 3 and 7 ft/sec in a line.
Thus, for a 300gpm flow (roughly one quarter of a T4 pump), you would need a 3/4-in. line, which is what I have used four-fold. Using a 3/4-in. line leads to a theoretical velocity of 7.38 ft/sec, but my T4 probably isn't putting out the 1225gpm it is rated for due to losses, so I fugure I am well within the 3 to 7 ft/sec range.
I highly recommend the Velocity Series of pumps.Moe_K said:
Yes. I had one on my 55gal. I went for a drilled one in my 90gal, though.Moe_K said:
Matt
Last edited:
Chuck Spyropulos
Non-member
Yes, I used to be a believer in closed loops until something much better and more efficient came along...Tunze Streams. Watt for watt you can't do better than these devices using closed loops. You really should look at these pumps woring in a reef tank and do the math before you settle on inefficient closed loops.
jango, reefnroll, you are missing the point and what I mean by efficient low velocity, High Volume water motion. Closed loops with conventional pumps produce narrow streams of water, unless you have many loops and many returns that add up to form a broad wavefront. I used to have 2 closed loops with an Iwaki MD100RLT on each.....4000 GPH TOTAL and the flow was extremely concentrated in narrow cones (4 since each return had a centipede return). Each pump consumed 3.4 amps for a total of 6.8 amps or 6.8x110 V = 748 Watts !
Now I have 4 Tunze Turbelle Streams, each of which provides 3000 GPH for a total of 12000 GPH. Each Stream pump uses approximately 45 watts x 4 = 180 watts a decrease in power usage of almost 75% and a factor of 4 increase in water motion. But another advantage is gained....due to the fact that the Streams are not conventional powerheads. They basically use propellers to move water with in a much broader cone than conventional pumps. This translates to more volume and lower velocity since the enrgy of the propeller is "spreading out" the water motion over a larger volume of water. Also, since the streams are close to the source,i.e., they do not have to pump water through a pipe, water motion is maximized when compared to conventional closed loop systems. Another advantage is that the pumps can be programmed to operate in many complex modes (6 hour tide simulation, pulsed mode, night mode, synchronous mode,etc...).
The Turbelles are German made and muche easier to clean than convenional pumps. Now with the new "magnetic holders" it is even easier to mount these devices in your tank. And in case of a power failure, it would not take much to keep these on using a backup power source.
jango, reefnroll, you are missing the point and what I mean by efficient low velocity, High Volume water motion. Closed loops with conventional pumps produce narrow streams of water, unless you have many loops and many returns that add up to form a broad wavefront. I used to have 2 closed loops with an Iwaki MD100RLT on each.....4000 GPH TOTAL and the flow was extremely concentrated in narrow cones (4 since each return had a centipede return). Each pump consumed 3.4 amps for a total of 6.8 amps or 6.8x110 V = 748 Watts !
Now I have 4 Tunze Turbelle Streams, each of which provides 3000 GPH for a total of 12000 GPH. Each Stream pump uses approximately 45 watts x 4 = 180 watts a decrease in power usage of almost 75% and a factor of 4 increase in water motion. But another advantage is gained....due to the fact that the Streams are not conventional powerheads. They basically use propellers to move water with in a much broader cone than conventional pumps. This translates to more volume and lower velocity since the enrgy of the propeller is "spreading out" the water motion over a larger volume of water. Also, since the streams are close to the source,i.e., they do not have to pump water through a pipe, water motion is maximized when compared to conventional closed loop systems. Another advantage is that the pumps can be programmed to operate in many complex modes (6 hour tide simulation, pulsed mode, night mode, synchronous mode,etc...).
The Turbelles are German made and muche easier to clean than convenional pumps. Now with the new "magnetic holders" it is even easier to mount these devices in your tank. And in case of a power failure, it would not take much to keep these on using a backup power source.
