Closed Loop Questions

[shermoen]

Attention all old school reefers or any whom have ran closed loop before!

I am in the works of setting up a 90 gallon acrylic cube. It will be Acro dominant and possibly have a Euphyillia garden on the bare bottom. It will be lit by a 250watt Metal Halide.

The tank has 4 holes drilled in the top eurobrace marked in red. The 2 holes furthest back by the overflow are the ones used for the return lines. I am wanting to cut 2 more holes in the top back corners marked by yellow and use those along with the 2 front holes as my returns into the tank.

From the picture you can also see the 2 bulkheads in the back of the tank on either side of the over flow. All of the bulkheads are cut for 1" pipes.

My current plan is lined out thusly.
* Use the back bulkheads to feed external pump/pumps.
* Feed from pump/pumps and drop a pipe in the yellow location with a T fitting and then daisy chain it to the red location directly in front of it.
* I will use bulkhead fittings on the tops to pipe in to and will be able to use 90's or 45's in the tank to direct where I want the flow to go.

From my research I have read that you want the flow to alternate back and forth from side to side. But I was thinking I could get a return pump for each side of the tank and controll them separately, something around 5000-9000 gallon and hour.

How does this sound? This is just me thinking about how to do this, with no experience what so ever. Please let me know what will work and won't.

 

[KrisReef]

I don't worry much about engineering the flow inside the filter. The flow inside the tank is more critical, but again water movement makes flow and if there is water pushing in from the side it will move the water in the tank. Your motion is going to be mostly at the surface with that set up, not a problem but it might not move much at the bottom.

Very critical (Possibly?) Those two bulkheads in the overflow wall, might create a vortex drawing water so that a little "tornado" starts to draw in air from the surface into the intake tubes, pumps, etc. I presume you will have a screen on them? They will be contained in a closed loop, not feeding into the sump where overflow issues might present?

 

[UncommonSense]

Attention all old school reefers or any whom have ran closed loop before!

I am in the works of setting up a 90 gallon acrylic cube. It will be Acro dominant and possibly have a Euphyillia garden on the bare bottom. It will be lit by a 250watt Metal Halide.

The tank has 4 holes drilled in the top eurobrace marked in red. The 2 holes furthest back by the overflow are the ones used for the return lines. I am wanting to cut 2 more holes in the top back corners marked by yellow and use those along with the 2 front holes as my returns into the tank.

From the picture you can also see the 2 bulkheads in the back of the tank on either side of the over flow. All of the bulkheads are cut for 1" pipes.

My current plan is lined out thusly.
* Use the back bulkheads to feed external pump/pumps.
* Feed from pump/pumps and drop a pipe in the yellow location with a T fitting and then daisy chain it to the red location directly in front of it.
* I will use bulkhead fittings on the tops to pipe in to and will be able to use 90's or 45's in the tank to direct where I want the flow to go.

From my research I have read that you want the flow to alternate back and forth from side to side. But I was thinking I could get a return pump for each side of the tank and controll them separately, something around 5000-9000 gallon and hour.

How does this sound? This is just me thinking about how to do this, with no experience what so ever. Please let me know what will work and won't.

The only flaw I spot is in plumbing sizing!

1” closed loop pump inlet to two 1” outlets is going to cause a cavitation risk in the pump at higher flow rates!

1" PVC Flow Rate?

What is the flow rate of 1" PVC? It is a full siphon herbie and will be going down about 12' if that changes anything.

www.reef2reef.com

You could always open the rear wall bulkheads up to 1.5”?

— I’m wondering if you can just use two smaller pumps, teed together to one larger closed loop return line, then two solenoid valves; alternating one open, one closed… this would alternate flow without excessive pump start/stop cycles daily, and prevent the need for larger pump inlet bulkheads!

 

[shermoen]

Very critical (Possibly?) Those two bulkheads in the overflow wall, might create a vortex drawing water so that a little "tornado" starts to draw in air from the surface into the intake tubes, pumps, etc. I presume you will have a screen on them? They will be contained in a closed loop, not feeding into the sump where overflow issues might present?

Those 2 bulkheads on the back will be plumbed directly to the pumps. Not in the sump. I am thinking about plumbing them through the wall into the laundry room to avoid any excess noise.

 

[KrisReef]

Those 2 bulkheads on the back will be plumbed directly to the pumps. Not in the sump. I am thinking about plumbing them through the wall into the laundry room to avoid any excess noise.

Great!
I would pay attention to the concern of @UncommonSense with regard to the flow capabilities of 1" pipe and cavitation.

Quick Googl says that maximum flow would be around 960gph, if I read the table correctly?

How Much Water Can Flow Through A Pipe (GPM/GPH)?

Three tables to get a general understanding of water flow capacity through a pipe or roof drain. If you have questions, contact our roof Drain Wizard.

resources.hy-techroof.com

 

[UncommonSense]

Great!
I would pay attention to the concern of @UncommonSense with regard to the flow capabilities of 1" pipe and cavitation.

Quick Googl says that maximum flow would be around 960gph, if I read the table correctly?

How Much Water Can Flow Through A Pipe (GPM/GPH)?

Three tables to get a general understanding of water flow capacity through a pipe or roof drain. If you have questions, contact our roof Drain Wizard.

resources.hy-techroof.com

Google is pretty useless for pipe flow rates… AI draws from articles on everything from atmospheric drain flow to flow at maximum pipe velocity… — a cursory glance shows one source quoting 3,540gph, at 18ft/sec… that would be at huge pressure!

I use this:

Flow Rate Calculator - Pressure and Diameter | Copely

Our Flow Rate Calculator will calculate the average flow rate of fluids based on the bore diameter, pressure and length of the hose.

www.copely.com

— I find it answers my questions better for our typical low to medium pressure return plumbing applications, particularly for the likes of RFG nozzles/etc!

 

[shermoen]

Flow rate would be the biggest issue it appears. This is something I am not completely comfortable understanding. In the chart below from it shows that 1" drain no pressure added is 600gph. But with average pressure that jumps up to 2,220 gph.

I wonder if the amount of water turnover would need to be the same in a closed loop vs power head situation. Power heads i always shoot for 15-20 X turnover. Would that need to be the same withthe closed loop?

I was thinking about using 2 seperate pumps that are DC controlled with random flow options. Otherwise the idea with the solenoid valves is great.

 

[KrisReef]

Flow rate would be the biggest issue it appears. This is something I am not completely comfortable understanding. In the chart below from it shows that 1" drain no pressure added is 600gph. But with average pressure that jumps up to 2,220 gph.

I wonder if the amount of water turnover would need to be the same in a closed loop vs power head situation. Power heads i always shoot for 15-20 X turnover. Would that need to be the same withthe closed loop?

I was thinking about using 2 seperate pumps that are DC controlled with random flow options. Otherwise the idea with the solenoid valves is great.

There is only 1 pressure (1ATM at sea level) pushing water into the overflow. If you had a pump pushing water into the pipe, that would add the presure that moves water in the circle. Having the pump in the middle of the loop, the intake side will tend to cavitate (pulling dissolved air out of the tank water) which can ruin a pump impeller over time. The passive flow into the pipe would be up to ~960 gph, according to the graph. Having a screen over the intake would likely reduce flow lower.

 

[shermoen]

There is only 1 pressure (1ATM at sea level) pushing water into the overflow. If you had a pump pushing water into the pipe, that would add the presure that moves water in the circle. Having the pump in the middle of the loop, the intake side will tend to cavitate (pulling dissolved air out of the tank water) which can ruin a pump impeller over time. The passive flow into the pipe would be up to ~960 gph, according to the graph. Having a screen over the intake would likely reduce flow lower.

I see. So like uncommon sense was saying regarding enlargement of the holes, would aid in that problem somewhat.

Dropping the return lines down to 3/4" would be another alternative. But that would reduce the amount of flow even further.

 

[KrisReef]

I see. So like uncommon sense was saying regarding enlargement of the holes, would aid in that problem somewhat.

Dropping the return lines down to 3/4" would be another alternative. But that would reduce the amount of flow even further.

Yes and Yes.

The fact that there is a maximum amount of flow doesn't preclude these intakes from being used for filtration. An inline variable speed pump would allow adjustments to flow-speed thru filtration and to prevent overdriving the intakes.

 

[UncommonSense]

I see. So like uncommon sense was saying regarding enlargement of the holes, would aid in that problem somewhat.

Dropping the return lines down to 3/4" would be another alternative. But that would reduce the amount of flow even further.

I would consider cheaper AC pumps and spending the extra $$$ on solenoid valves; this way you could realistically run two 1” inlet pumps in parallel, switching which side of the closed loop system they both feed!

Or, just increase the closed loop pump intake bulkhead size to 1.5” and you’re set!

— it’s worth asking at this point; what is your plan for nozzles on the outlets of this closed loop? I’d imagine RFGs might be the way to go! They are inherently restrictive, though… This would call for a higher pressure, lower flow closed loop pump style…

And to answer the earlier question; closed loops predate modern, efficient powerhead designs; they serve the same purpose as powerheads, just in a bigger, more complex package! (Though they do still do away with any cords or equipment in the DT!

 

[shermoen]

I would consider cheaper AC pumps and spending the extra $$$ on solenoid valves; this way you could realistically run two 1” inlet pumps in parallel, switching which side of the closed loop system they both feed!

This is a good idea. In order to control the solenoid valves i would need some sort of controller though. Correct?

— it’s worth asking at this point; what is your plan for nozzles on the outlets of this closed loop? I’d imagine RFGs might be the way to go! They are inherently restrictive, though… This would call for a higher pressure, lower flow closed loop pump style…

I was thinking I could fab up som nozzles from pvc fittings. This is where I though using a couple jebao dc pumps with wave/random settings on them in order to do so. They run about 80.00 a piece.

 

[UncommonSense]

This is a good idea. In order to control the solenoid valves i would need some sort of controller though. Correct?

If the solenoid valves are 120v AC, it could be as simple as two mechanical light timers; set to turn on/off every 15-30mins, alternating!

Or you could get fancier with an aquarium controller/simple wave maker controller such as hydro makes!

I was thinking I could fab up som nozzles from pvc fittings. This is where I though using a couple jebao dc pumps with wave/random settings on them in order to do so. They run about 80.00 a piece.

I recommend looking into “eductors”! An RFG is just a modified eductor, they are a device used in this application for water mixing, and you could realistically make your own…

Or, employ one of several plumbing part nozzle tricks; though many of these will flow only as much as the pump can, in effect…

 

[Baylott224]

Just get a fluval fx6 lol

 

[Baylott224]

One and done u can tell feed the return into uvc or reactor

 

[UncommonSense]

One and done u can tell feed the return into uvc or reactor

lol… “just spend over $350 to have a high maintenance nitrogen factory that moves maybe a third of your target flow rate”

 

[shermoen]

Just get a fluval fx6 lol

Not really sure how that will help me out

 

[Baylott224]

Your. Right

 

[shermoen]

If the solenoid valves are 120v AC, it could be as simple as two mechanical light timers; set to turn on/off every 15-30mins, alternating!

I didn't even think of this. Great idea, not sure if its the way ill go but good knowledge to have!

 

[UncommonSense]

I didn't even think of this. Great idea, not sure if its the way ill go but good knowledge to have!

Let me know if you’d like a few tricks on increasing the diameter of a hole-sawn hole accurately, or drilling acrylic in general!