Closed Loop Flow Questions

[CaptainKiwi]

I am planning a 5 ft x 2 ft x 1.5ft LWH FOWLR build and would like to have a closed loop since I do not want power heads for aesthetics reasons. I am aiming to have around 1500gph an will be using an old 40 gallon aquarium as a sump and I was wondering if that would be ok in handling the flow that would be required to run the closed loop? I was also wondering if this flow would be too much for the protein skimmer to work properly? I will be using 1.5" intakes using the bean animal method and using 2 1" on the return.

Here is a model of the tank with the two outlets on the left and the weir on the right.

 

[Shirak]

It's not a closed loop if you are dumping water over the weir into a sump and pumping back up again. Your basically wanting to have 1500gph going over the weir into the sump and up to the tank again. You can do that but 1500gph going through a 40g sump will have maybe 20g in it when running? So your turnover will be 75x an hour. It will be like a fast flowing river through your sump.

A closed loop is a suction drain/drains underwater on one side of the tank that goes directly into a pump and then is pumped back into the tank through a bulkhead/bulkheads somewhere else. You could add a closed loop if you wanted to drill some holes or use one of those hang on U type overflows to supply an external pump with corresponding U return. This is why drop in powerheads are such a big thing now.

There are some pretty low profile powerheads now and getting 1200gph is easy. I would suggest a couple wave makers up high. One on each side. They are not as obtrusive to the eye and move a lot of water. Then you can tailor flow through your sump as needed for proper filtration.

 

[CaptainKiwi]

It's not a closed loop if you are dumping water over the weir into a sump and pumping back up again. Your basically wanting to have 1500gph going over the weir into the sump and up to the tank again. You can do that but 1500gph going through a 40g sump will have maybe 20g in it when running? So your turnover will be 75x an hour. It will be like a fast flowing river through your sump.

A closed loop is a suction drain/drains underwater on one side of the tank that goes directly into a pump and then is pumped back into the tank through a bulkhead/bulkheads somewhere else. You could add a closed loop if you wanted to drill some holes or use one of those hang on U type overflows to supply an external pump with corresponding U return. This is why drop in powerheads are such a big thing now.

There are some pretty low profile powerheads now and getting 1200gph is easy. I would suggest a couple wave makers up high. One on each side. They are not as obtrusive to the eye and move a lot of water. Then you can tailor flow through your sump as needed for proper filtration.

Ok, it sounds like a closed loop is more hassle than its worth, I will just go with wave makers. What general turnover through the sump should I aim for?

 

[Shirak]

Ok, it sounds like a closed loop is more hassle than its worth, I will just go with wave makers. What general turnover through the sump should I aim for?

Sorry I miscalculated turn over .. it's based on tank volume. You have about a 100g tank so 1500gh through the sump would be 15x turn over. Generally 5x turn over is good for filtration. I am going to take back what I said earlier. You could run 1500gph through the sump, It's a little fast but if you are only doing basic filtration like socks to collect particles it should be fine.

 

[Shirak]

Personally I would go with 2 return pumps 1000gph each. Or something a little smaller if you want to run a wavemaker in the tank and slow the flow a little through the sump. That way if something happens to one then water is still flowing and the tank won't go without oxygen. Especially since you are running primarily a fish tank.

 

[Shirak]

Years ago when people realized they needed flow in a reef tank for more SPS corals they would go 25-50x turnover through the sump because wavemakers/powerheads were not up to the task but big external pumps were! I had one of these.. lol They got HOT! But it was going fast through the sump so.. it mainly was to catch some stuff with socks and a counter current skimmer with wood air stones! think I am dating myself lol

 

[mfinn]

Ok, it sounds like a closed loop is more hassle than its worth, I will just go with wave makers. What general turnover through the sump should I aim for?

not really, but you do have to have a suction from the tank directly, and then returns back to the tank. Completely separate for the sump.
I've done closed loops 2 different ways.
I've plumbed a mag 18 ( a couple others too) with a over the top of the tank suction with the return going to 2 outlets in the tank. This was a pain to prime, because of the suction ability of the pump to suck.
My current closed loop has a 1-1/2" bulkhead in the back wall of my tank for suction and 4 return bulkheads in the back wall of the tank.
It's really pretty easy, just needs a little planning.

 

[areefer01]

It's really pretty easy, just needs a little planning.

Such a critical point to make. Design and planning. GJ!

 

[mfinn]

Such a critical point to make. Design and planning. GJ!

That is half the fun.

 

[CaptainKiwi]

Sorry I miscalculated turn over .. it's based on tank volume. You have about a 100g tank so 1500gh through the sump would be 15x turn over. Generally 5x turn over is good for filtration. I am going to take back what I said earlier. You could run 1500gph through the sump, It's a little fast but if you are only doing basic filtration like socks to collect particles it should be fine.

1500 is reasonable, I'll get a 2000 just for some headroom! Will a skimmer work efficiently at that speed?

 

[CaptainKiwi]

not really, but you do have to have a suction from the tank directly, and then returns back to the tank. Completely separate for the sump.
I've done closed loops 2 different ways.
I've plumbed a mag 18 ( a couple others too) with a over the top of the tank suction with the return going to 2 outlets in the tank. This was a pain to prime, because of the suction ability of the pump to suck.
My current closed loop has a 1-1/2" bulkhead in the back wall of my tank for suction and 4 return bulkheads in the back wall of the tank.
It's really pretty easy, just needs a little planning.

That is half the fun.

Thank goodness for CAD software, it means I've just been sat here cycling through all the different things I could do and its been awesome! I think for ease of maintenance long term and to avoid drilling more holes I'm just going to get some wave makers and attempt to hide them creatively. Slightly boring, but I think thats what works for me...

 

[UncommonSense]

I'm just going to get some wave makers and attempt to hide them creatively. Slightly boring, but I think thats what works for me...

It’s worth noting that there are baseball sized modern wave makers which draw only 11W of power for 3,000+GPH!

These are exponentially more power efficient (to the tune of 10-20X) at moving water!

(Also note that some brands can have their clamping magnet submerged, meaning that you can mount these wave makers directly to the walls of an overflow!)

 

[areefer01]

It’s worth noting that there are baseball sized modern wave makers which draw only 11W of power for 3,000+GPH!

These are exponentially more power efficient (to the tune of 10-20X) at moving water!

(Also note that some brands can have their clamping magnet submerged, meaning that you can mount these wave makers directly to the walls of an overflow!)

Sure, the Tunze eco's move water for little to no power. Optional ORCA due out hopefully by end of year which allows some oscillation control.

 

[Shirak]

1500 is reasonable, I'll get a 2000 just for some headroom! Will a skimmer work efficiently at that speed?

Skimmers are self contained with their own pumps so they will work fine in moving water. The main issue with skimmers is if microbubbles escape the skimmer they will end up back in the tank. It's harder to minimize this if the water is flowing very fast through the sump.

I read your other post and it sounds like you are planning to put a wave maker/powerhead in the tank? If so I wouldn't worry too much about getting a ton of flow through the sump then.

 

[CaptainKiwi]

Skimmers are self contained with their own pumps so they will work fine in moving water. The main issue with skimmers is if microbubbles escape the skimmer they will end up back in the tank. It's harder to minimize this if the water is flowing very fast through the sump.

I read your other post and it sounds like you are planning to put a wave maker/powerhead in the tank? If so I wouldn't worry too much about getting a ton of flow through the sump then.

Yeah, it means I just dont have to think about as many things, plus i can hide the wave makers with clever placement so I think im going to go down that route :)

 

[mfinn]

Thank goodness for CAD software, it means I've just been sat here cycling through all the different things I could do and its been awesome! I think for ease of maintenance long term and to avoid drilling more holes I'm just going to get some wave makers and attempt to hide them creatively. Slightly boring, but I think thats what works for me...

What makes it work for each individual is what is important. There are a lot of options.
When I first started in the hobby back in the 80's it was known that flow was important, but the only route I found was powerheads. Between powerheads that failed ( and needing 3-4 or more ) and suction cups being the only way to hold them in place, I was very happy when I saw my first closed loop at a reef club members meeting at his home.
To be able to use 1 device and possibly create all the flow needed in a reef tank was like opening a new chapter for me. Plus freeing up the outlets back then was a win for me.
With today's many different types and styles of powerheads/wavemakers, you can create any flow you need.

 

[areefer01]

Yeah, it means I just dont have to think about as many things, plus i can hide the wave makers with clever placement so I think im going to go down that route :)

Whatever route you go - just don't outsmart yourself with hiding things. It becomes a major issue when maintenance comes due. And yes, maintenance is required regardless of what hobbyist A or B says.

 

[WhatCouldGoWrong71]

Ok, it sounds like a closed loop is more hassle than it’s worth, I will just go with wave makers. What general turnover through the sump should I aim for?

It depends what you are doing. I’m a stick head, and I would never do a tank without at least 1 closed loop. Here is my current main display, it has 3 closed loops. The top left has 2 sea swirls on an L2, the same goes for the right. The bottom of the tank is driven by an Abyzz. I had to modify the 3 returns, they have threaded street 90’s pointing up to prevent sand from getting sucked in. But it depends on your goals. These loops help me to achieve about a 150x turnover in my display, which allows me to cook my coral with my par at 550-600 in the sand, which also allows me to feed 12 times a day. Like said. What type of tank, what do you want to achieve, once you understand that, you can think through your plans. I would never do a loop in a softie, LPS or a Mixed reef. With advancements like Tunze’s Orca, there are other ways to strive for true random flow. But, loops are also very very cost effective. But, NEVER do a loop with those cheap ABS black bulkheads. If you are going to do one, spend the money and go Hayward. That’s all I use on my closed loops. The 1/4 EPDM gaskets are legit and never use grease on bulkhead fittings like you would on unions, reactors, threads, etc.

 

[CaptainKiwi]

It depends what you are doing. I’m a stick head, and I would never do a tank without at least 1 closed loop. Here is my current main display, it has 3 closed loops. The top left has 2 sea swirls on an L2, the same goes for the right. The bottom of the tank is driven by an Abyzz. I had to modify the 3 returns, they have threaded street 90’s pointing up to prevent sand from getting sucked in. But it depends on your goals. These loops help me to achieve about a 150x turnover in my display, which allows me to cook my coral with my par at 550-600 in the sand, which also allows me to feed 12 times a day. Like said. What type of tank, what do you want to achieve, once you understand that, you can think through your plans. I would never do a loop in a softie, LPS or a Mixed reef. With advancements like Tunze’s Orca, there are other ways to strive for true random flow. But, loops are also very very cost effective. But, NEVER do a loop with those cheap ABS black bulkheads. If you are going to do one, spend the money and go Hayward. That’s all I use on my closed loops. The 1/4 EPDM gaskets are legit and never use grease on bulkhead fittings like you would on unions, reactors, threads, etc.

I will be going for a soft/lps coral tank, i really like the look of torches and apparently they need a medium flow?

 

[Freenow54]

Thank goodness for CAD software, it means I've just been sat here cycling through all the different things I could do and its been awesome! I think for ease of maintenance long term and to avoid drilling more holes I'm just going to get some wave makers and attempt to hide them creatively. Slightly boring, but I think thats what works for me...

I got this far in the thread the only thing I will say is since I too don't use power heads but my return pump is DC isn't yours ? If not just get a valve usually I always say to use a globe valve for controlling flow , but this seems like a one time thing so set your flow wherever you decide and stay with that