...are closed loops becoming obsolete?

[143MPCo]

....this might be a really dumb question but what exactly is a closed loop system and what makes it different than a normal tank w/sump?

The pumps are used as powerheads, a sump is still used/needed but runs remotely and still requires yet an additional return pump.

 

[Helenareefer]

That right there was a huge issue for my closed loop system.
Priming the pump.
I was using a reeflo pump and had to build a stand pipe to prime it after cleaning.

No way to use a check valve to remove air, or an air pump?

 

[twilliard]

I was using 2" and what I found that helped a lot was putting the pump lower than the tank (it was located in another room) and put a ball valve on. Most of the time gravity worked for me when I fired it all back up. Other times I had to fill the pump cause it wanted to cavitate.
I since then have never used a closed loop system.
Too much trouble

 

[dbl]

thank you for sharing this!
$30 a month more?

Yes, three pumps (main, CL and Skimmer), lights, other items, my bill only increased by $30/month.

Alex...while we are on the subject, and I realize there have been some other threads, but the new Ecotech Vectra pumps seems to be a good option for CL use. They have the CL controls built in to them and seem like a viable option for those of us with CL's. I'm considering one but since I'm in the process of installing/programming an Apex, I'm thinking I will wait until they are controllable via Apex.

That right there was a huge issue for my closed loop system.
Priming the pump.

Lastly, for what it's worth on the priming issue, and in my personal situation, my CL feeds are about 4-5' above the pump. So when the CL is turned off, the water in the lines more or less serve as the prime. I know it works well because my CL outlets (again, mine are over the top) are exposed during water changes, and I've never had a problem with the CL firing back up. I'm hoping I didn't just jinx myself!

 

[pciscott]

I have 2 closed loops on my 400 and just upgraded to Red Dragon Speedy 230 pumps. They are running at 150 watts during the day and put out about 3500 gallons each output(at 150 watts) and 3500 gallons of suction on the back wall of my peninsula. They input water via 6 Sea Swirls on the top and a Oceans Motions 6 way valve on the bottom and create a random hidden flow. This is why I choose Closed Loop over Power heads on a Peninsula tank. I turn the pumps down in the evening to 80 watts each, and Blast the tank with 230 watts a couple times a week all controlled on my Apex.

I think aesthetics and the advent of these controllable pumps will keep the Closed Loop alive, but yes they are more difficult to build and are much more costly. I have 10 holes outside my overflow under the water line and have never had a Leak in 4 years. Knock on wood

The New Vectra pumps are a good argument to keep closed loops alive as well, neat little pump. I have the M1 on a closed loop in my frag tank on a Oceans motions as well. The Reef Crest mode matches the MP10's I use for flow on this tank.

 

[143MPCo]

Alex...while we are on the subject, and I realize there have been some other threads, but the new Ecotech Vectra pumps seems to be a good option for CL use. They have the CL controls built into them and seem like a viable option for those of us with CL's. I'm considering one but since I'm in the process of installing/programming an Apex, I'm thinking I will wait until they are controllable via Apex.

The New Vectra pumps are a good argument to keep closed loops alive as well, neat little pump. I have the M1 on a closed loop in my frag tank on a Oceans motions as well. The Reef Crest mode matches the MP10's I use for flow on this tank.

wattage wise they're roughly half of the reeflo pumps, and would make a better option for a CL implementation, thank you for sharing that!

 

[Saltgator]

Following. I'm building a 230 with a CL but have never ran one. Was liking the idea of not using any extra equipment within the tank itself but never really totaled the cost over a year! Might just cap the three bulkheads off and go back to my Jebao pumps and two simple returns, lol.

 

[143MPCo]

so figure I should run the numbers to the newer DC return pumps, just for comparison sake...

Vectra L1
Flow: 3,100 gph
Power
Wattage: 130 watts

130watts X 24 hours = 3,120 watt-hours per day
3,120 watt-hours per day / 1000 = 3.12 kWh per day
3.12 kWh per day X 30 days =93.6 kWh per month
93.6 kWh per month x $0.12 per kWh = $11.23 per month (one pump)
$11.23 x 1yr = $134.78 not including line fees and tax.

Same breakdown of the aforementioned DC powerhead noted before, will cost you $62.20 a yr (one pump) to run, again not including line fees and tax.

Note: the flow is less than Aqua Medic EcoDrift @ 2,641 – 5,283 gph and less than either reeflo return pumps Hammerhead Gold Maximum Flow Rate: 5,555 gph, Barracuda Gold Maximum Flow Rate: 4,680 gph.

I have to admit after total cost of ownership and running expenses it's really flow that we are looking to create.

 

[TylerS]

Since this hasn't been mentioned yet, I thought I'd point out that those flow rates are at 0 ft of head. You'll have head loss due to the intake, pipes to the pump, pipes from the pump, and outlets. I've done the calculations before and the loss isn't negligible, so actual flow from the pump is less. You can get additional flow with the same pump by using things like eductors, but overall my calculations showed that CL can't compete with powerheads for efficiency due to the mechanics of having to pump water through a pipe vs just moving the water in the tank.

Powerheads have virtually no head loss. They are also re-positionable, easy to scale up or down and don't require holes in the tank (good for re-sale value, and eliminates a source of leaks).

I think the only thing closed loops have going for them are aesthetics. I wonder why no-one is working on powerheads and in tank circulation devices that fit under rock work, or don't require attachment to the side glass of the tank... (maybe using mass to keep them in place?).

 

[Helenareefer]

I suppose you could run a CL pump from directly in the DT behind some rock work if you choose. That would eliminate some of the head loss. Just speculating of course.


Probably suck up a lot of critters though...

 

[143MPCo]

Since this hasn't been mentioned yet, I thought I'd point out that those flow rates are at 0 ft of head

it was mentioned in my first post
"that's a flowrate at 0 head pressure and when all the plumbing is said and done on a closed loop, flow is and will be less."

 

[143MPCo]

You can get additional flow with the same pump by using things like eductors, but overall my calculations showed that CL can't compete with powerheads for efficiency due to the mechanics of having to pump water through a pipe vs just moving the water in the tank.

Powerheads have virtually no head loss. They are also re-positionable, easy to scale up or down and don't require holes in the tank (good for re-sale value, and eliminates a source of leaks).

good points!

 

[dbl]

Let's cloudy the proverbial water a little more...

Admittedly, I may be completely wrong, but I remember reading where head loss in a CL system is negligible. Did a quick search on the ole’ interweb and came across one of the articles I remember reading when I was getting started. Granted it’s rather dated, but here is the link. Towards the end of the article is the following paragraph (I've underlined the sentence I remembered reading):

"A very valuable benefit of a closed loop system is that there are no head height restrictions. The rating of the pump is what you should get – even if the pump is three feet lower than the display aquarium. Head height is effectively due to gravity where the water when rising up a tube has to fight against this natural force. The pump can only pump the water so high and then simply runs out of power. If a pump has a four foot head height then at four foot above the pump the water flow will stop, at two foot above the pump the flow will be halved etc. With a closed loop aquarium head height does not exist. The reason for this is that the water does not have to fight against gravity as no air is allowed into the pipe work. The inlet pipe is continuously full of water as is the outlet therefore with no gravity to fight against you get full use of the power of the pump!"

I also remembering reading you have to account for friction loss, but again, I may be completely off base here.

Disclaimer...I'm not a CL guru, heck, I'm not a guru in anything, so don't lambast me here. I just remember reading about the minimal effect on head loss in a CL system. One thing I do know in this hobby, if you ask 10 people one question, you will get 12 answers!!!

 

[abecker]

Let's cloudy the proverbial water a little more...

Admittedly, I may be completely wrong, but I remember reading where head loss in a CL system is negligible. Did a quick search on the ole’ interweb and came across one of the articles I remember reading when I was getting started. Granted it’s rather dated, but here is the link. Towards the end of the article is the following paragraph (I've underlined the sentence I remembered reading):

"A very valuable benefit of a closed loop system is that there are no head height restrictions. The rating of the pump is what you should get – even if the pump is three feet lower than the display aquarium. Head height is effectively due to gravity where the water when rising up a tube has to fight against this natural force. The pump can only pump the water so high and then simply runs out of power. If a pump has a four foot head height then at four foot above the pump the water flow will stop, at two foot above the pump the flow will be halved etc. With a closed loop aquarium head height does not exist. The reason for this is that the water does not have to fight against gravity as no air is allowed into the pipe work. The inlet pipe is continuously full of water as is the outlet therefore with no gravity to fight against you get full use of the power of the pump!"

I also remembering reading you have to account for friction loss, but again, I may be completely off base here.

Disclaimer...I'm not a CL guru, heck, I'm not a guru in anything, so don't lambast me here. I just remember reading about the minimal effect on head loss in a CL system. One thing I do know in this hobby, if you ask 10 people one question, you will get 12 answers!!!

That does make sense since the same pressure the pump has to pump up is also being directed down on the pump at the same time.

 

[143MPCo]

Very interesting article thank you for posting it...

Two things noted from it below (not in order)...

The second thing to plan for is the amount of outlets per loop. It is recommended that you do not go above three outlets per loop as the reduction in flow may be too much. Pumps are rated in accordance with the size of the outlet coming out of the pump and with a pump there is only one outlet. If you put three outlets onto a closed loop then effectively the output from the pump per outlet will reduce. Normally in a loop this reduction is staged with the last outlet having the weakest route.

The first consideration is that of water flow and friction. Water will always find the easiest route and follow it which is one of the reasons you need to plan your plumbing. If you implement a tee piece for example the water in the pipe will travel down the easiest route and therefore water flow down the secondary path may be severely impacted. Friction is also the same – although the inside of the pipe feels smooth to the touch it will create friction when in contact with the pipe. When in a straight line this friction is not a problem however bends are another kettle of fish altogether. If you need to go around a bend it is easy to install a 90 degree bend however this is quite a bend for the water to go around and the flow will be severely impacted as well as creating back pressure within the pipe which over time may damage the pump itself. If you need to go around a corner then it is better to use two 45 degree bends instead of a single 90 degree bend. Even better is to use rigid pipe which is slightly flexible which will allow you to create a gentle curve around corners.

Can the same be said about powerheads?

 

[Newtybar]

Wouldn't it still be a closed loop with a DC pump or am I missing something?

 

[dbl]

Wouldn't it still be a closed loop with a DC pump or am I missing something?

You're not missing anything. The thread started as an energy usage discussion, and the notion of using a DC pump in a CL system was simply a method of energy conservation.

 

[ballroomdude]

...at MACNA 2015 I recall Sanjay Joshi talking about how closed loops have become obsolete with the introduction of DC powerhead at a cheaper price point... he made a compelling argument related to cost of an additional pump/s or more, PVC plumbing needs, and the fact that DC powerheads have becoming considerably more reliable... he also noted the the kilowatt an hour cost to run the big closed loop pump on a system was an additional factor in his research and why he's moving away or considering moving away from closed loops.

...personally, whether or not this move away from closed loops becomes mainstream or not is questionable, I'm all for saving money anyway I can as my electric bill is high enough and why I opted not to go closed loop... one just has to look at wattages used on a AC vs DC pump to see that you're at a much higher kilowatt an hour cost for just one pump.

A quick side by side and break out (I just picked a DC powerhead I saw at MACNA, sure others might be better)...

Aqua Medic EcoDrift 20.0 with Controller
Power Consumption: 20 – 60 watts

Specifications (Hammerhead Gold):
Maximum Wattage: 297W
Average Wattage: 272W

Specifications (Barracuda Gold):
Maximum Wattage: 253W
Average Wattage: 237W

...this roughly equates to 4 Aqua Medic EcoDrift powerheads each with an adjustable capacity flowrate of 2641 – 5283 gph (inside your systems with no head pressure concerns), one Hammerhead Gold Maximum Flow Rate: 5555gph, Barracuda Gold Maximum Flow Rate: 4680gph. you also need to consider, that's a flowrate at 0 head pressure and when all the plumbing is said and done on a closed loop, flow is and will be less.

Your Hammerhead Gold runs 24 hours a day, and consume 297 watts of electricity.

297 watts X 24 hours = 7,128 watt-hours per day
7,128 watt-hours per day / 1000 = 7.12 kWh per day
7.12 kWh per day X 30 days = 213.84 kWh per month
213.84 kWh per month x $0.12 per kWh = $25.66 per month (one pump)
$25.66 x 1yr = $307.92 not including line fees and tax.

Same breakdown of the above DC pump will cost you $62.20 a yr (one pump) to run, again not including line fees and tax.

So I'm curious to know what you all think, aesthetics aside, are closed loops becoming obsolete?

Its funny you posted this as I was doing this exact math with these exact powerheads this morning for my build. The $ saved in relation to the flow I'm looking for makes me not care about cords in the tank. thanks for an awesome thread.

 

[143MPCo]

I concede (man that's a strong word) that aesthetically closed loop's may not be going away anytime soon. energy conservation-wise the systems yearly expense makes them (CL) far less attractive (feel we can all agree to that one), even the newer DC return bumps while less expensive but, a better alternative to run, are still more expensive than some DC powerheads that can achieve the same if not better flow requirements that we reef-heads want... this has bigger implications and recently I started looking at alternatives to reduce my energy consumption across a wider expanse both aquarium and no-aquarium related.

Food for thought... (hesitated to post this bit last night, as these are my personal beliefs and I apologize if I inadvertently offend anyone, it's not my intent to sway ppl with the post). Recently in the news we've all seen (unless you live under a liverock) broadcast/s about a world wide coral bleaching event going on... whenever you save energy, you not only save money, you're also reduce the demand for such fossil fuels as coal, oil, and natural gas (where did you think most of the electricity you use came from)... less burning of fossil fuels also means lower emissions of carbon dioxide (CO2), the so-called primary contributor to global warming, and other pollutants.

to me, NOAA's statement below is reason enough to try and cut back as much as we can if we want to have coral reefs around long term, and not in just some glass box that we have sitting in our living rooms, yeah I hijacked my own thread, it's still somewhat relative to the conversation.

Climate change impacts have been identified as one of the greatest global threats to coral reef ecosystems. As temperature rise, mass bleaching, and infectious disease outbreaks are likely to become more frequent. Additionally, carbon dioxide (CO2) absorbed into the ocean from the atmosphere has already begun to reduce calcification rates in reef-building and reef-associated organisms by altering seawater chemistry through decreases in pH (ocean acidification). In the long term, failure to address carbon emissions and the resultant impacts of rising temperatures and ocean acidification could make many other coral ecosystem management efforts futile.

http://coralreef.noaa.gov/threats/climate/

 

[redfishbluefish]

I believe closed loop still has a place in the hobby.....for large tanks. I won't pick a size at which you should consider closed loop, but give an actual example of a local club member who has gone CL. He has a 600 gallon tank and between the thickness of the acrylic and the size of the tank, the only way he could get flow towards the center of the tank was with CL. And DC pumps can now replace those 120V power hungry pumps that are common and currently being used. I quickly looked up Deepwater DC15 pump that pumps 4000 gph and uses 132W. I now wonder what Bill Wann uses on his tank?