Unique sump and completely hidden plumbing design question

[jnadz]

I am designing a new tank that will go under a window so the stand would be very short. I would like to plumb in a remote sump but for reasons too wordy to explain here, I cannot have any significant fall in the drain lines even though the bottom of the sump could sit about 12” below the bottom of the tank. I was about to ditch the remote sump idea when I thought of another option which would also allow for completely hidden and silent drains and returns.

The idea is to plumb the drains into the bottom of the aquarium and draw the water through a spa drain type cover hidden near the rock work at the bottom of the tank. The returns would also be drilled through the bottom and come up through the rocks. Now, I know what you’re thinking…. What about a power outage and siphoning all water out of the tank. Here’s the proposed solution. The sump would also be plumbed so the drain lines coming in were underwater and I would build a stand for the sump so the water level of the sump would be at the exact water level of the tank when all power was off. Turning the power on to the returns would cause a slight increase in the water level in the display and thus a pressure gradient to return the water to the sump. However, a loss of power would simply return both to the equal level.

Has anyone tried anything like this or see any problem with the logic?

 

[bast]

I am designing a new tank that will go under a window so the stand would be very short. I would like to plumb in a remote sump but for reasons too wordy to explain here, I cannot have any significant fall in the drain lines even though the bottom of the sump could sit about 12” below the bottom of the tank. I was about to ditch the remote sump idea when I thought of another option which would also allow for completely hidden and silent drains and returns.

The idea is to plumb the drains into the bottom of the aquarium and draw the water through a spa drain type cover hidden near the rock work at the bottom of the tank. The returns would also be drilled through the bottom and come up through the rocks. Now, I know what you’re thinking…. What about a power outage and siphoning all water out of the tank. Here’s the proposed solution. The sump would also be plumbed so the drain lines coming in were underwater and I would build a stand for the sump so the water level of the sump would be at the exact water level of the tank when all power was off. Turning the power on to the returns would cause a slight increase in the water level in the display and thus a pressure gradient to return the water to the sump. However, a loss of power would simply return both to the equal level.

Has anyone tried anything like this or see any problem with the logic?

Can you draw it out?

 

[Troylee]

If the sump is under it that would never work.. next to the tank at the same level, sure it would be fine.

 

[JonoH]

I have seen returns up high hidden by rocks in the centre of a tank before, that part can work, but you couldnt have the sump at the same level as the water wouldnt 'flow' from one to the other.
There would end up water never transferring between one and the other, but simply just enough to remain level with one another (probably doesnt make sense...).

The only way it would work was if the water would be pumped out, then pumped back in, but that is fraught with danger!

 

[Troylee]

I have seen returns up high hidden by rocks in the centre of a tank before, that part can work, but you couldnt have the sump at the same level as the water wouldnt 'flow' from one to the other.
There would end up water never transferring between one and the other, but simply just enough to remain level with one another (probably doesnt make sense...).

The only way it would work was if the water would be pumped out, then pumped back in, but that is fraught with danger!

Agreed yeah it would need a pump both ways…

To the op what’s the reason for the sump? I mean it sounds like you want a closed loop which is fine it’s basically just flow that hidden and works well.. if you want the sump for equipment then it’s a different story.

 

[DCR]

You only need to pump one way. The sump level would be pulled down and the tank level would rise when you turned on the return pump. I have done something similar with two side by side tanks with one flowing to the other and the only caution I would have is that the difference between the tank and the sump level when flowing can be substantial (like several inches). You need some very large drain lines (like 2") to minimize the difference in levels. I would recommend still using an overflow box on the display and just have your sump at a lower level next to the display rather than coming off the bottom of the display. That way you will not drain down your display so much when the return pump goes down. You should be able to create a head difference of 8-12 inches with something like that.

 

[JonoH]

You only need to pump one way. The sump level would be pulled down and the tank level would rise when you turned on the return pump. I have done something similar with two side by side tanks with one flowing to the other and the only caution I would have is that the difference between the tank and the sump level when flowing can be substantial (like several inches). You need some very large drain lines (like 2") to minimize the difference in levels. I would recommend still using an overflow box on the display and just have your sump at a lower level next to the display rather than coming off the bottom of the display. That way you will not drain down your display so much when the return pump goes down. You should be able to create a head difference of 8-12 inches with something like that.

Relying on just gravity to balance the tanks back out with only one pump would result in very low flow though i'm pretty sure, depending on the turnover your after it could work but it would be slow.

 

[DCR]

Relying on just gravity to balance the tanks back out with only one pump would result in very low flow though i'm pretty sure, depending on the turnover your after it could work but it would be slow.

That is true which is why I said the lines have to be really oversized and even then you need a significant freeboard in the display and the sump for changes in water level. Pumping both directions is almost sure to lead to a major overflow at some point when one of the pumps stops working while the other continues. I would never recommend pumping both directions.

 

[JonoH]

That is true which is why I said the lines have to be really oversized and even then you need a significant freeboard in the display and the sump for changes in water level. Pumping both directions is almost sure to lead to a major overflow at some point when one of the pumps stops working while the other continues. I would never recommend pumping both directions.

Agree with that! I would never recommend that either!

 

[DCR]

The other thing you could do is to buy and oversized tank lengthwise and just put an internal overflow weir in the tank to the sump located on one end of the tank or in the back - an AIO type set-up but with a larger sump. It would really depend on the size of the tank, but it would be the most reliable set-up for a side-by-side arrangement. I have also seen people use the internal overflow weir and then extend a large diameter pipe (2") or a couple of pipes out the side or back of the tank horizontally directly to the sump and enter the sump under the sump water level from the side. I think that would work as well but there has to still be a pretty good difference between the tank overflow and the water level in the sump (8-12 inches I would think)

 

[jnadz]

I have seen returns up high hidden by rocks in the centre of a tank before, that part can work, but you couldnt have the sump at the same level as the water wouldnt 'flow' from one to the other.
There would end up water never transferring between one and the other, but simply just enough to remain level with one another (probably doesnt make sense...).

The only way it would work was if the water would be pumped out, then pumped back in, but that is fraught with danger!

The water will flow once water is pumped from the sump to the main tank. Think about two cups held at the same height, filled with water, with a tube connecting them at the bottom of each cup… If you take some water out of one cup and put it in the other (which is what a return pump does), the water will flow back into the original cup.

 

[jnadz]

Agreed yeah it would need a pump both ways…

To the op what’s the reason for the sump? I mean it sounds like you want a closed loop which is fine it’s basically just flow that hidden and works well.. if you want the sump for equipment then it’s a different story.

Yes, the sump is for equipment (heater, protein skimmer, algae scrubber, etc). Also plan to do water changes in the remote sump vs my living room.

I really don’t think I need a pump both ways. As I replied before. Think about two cups half filled with water, held at the same height, and connected by a tube in the bottom of each cup. If you take water from one cup and put it in the other cup (which is what a return pump does), the water will naturally flow and even itself out. That’s physics.

 

[jnadz]

You only need to pump one way. The sump level would be pulled down and the tank level would rise when you turned on the return pump. I have done something similar with two side by side tanks with one flowing to the other and the only caution I would have is that the difference between the tank and the sump level when flowing can be substantial (like several inches). You need some very large drain lines (like 2") to minimize the difference in levels. I would recommend still using an overflow box on the display and just have your sump at a lower level next to the display rather than coming off the bottom of the display. That way you will not drain down your display so much when the return pump goes down. You should be able to create a head difference of 8-12 inches with something like that.

Thank you for your reply. I think you understand my theory.

My plan was to experiment with that height difference and make sure there is enough head room in the sump to catch that water difference when powered off. The plumbing I had planned was two 2” drain lines and two 1” returns. The double return is only for redundancy though.

To limit drop in the display when power was off, couldn’t I simply plumb the returns into the bottom of the sump but bring the pipe up to a certain height where I would want the drainage from the display to stop when powered off? Ie, wouldn’t flow stop as soon as the level of the sump reached that pipe height?

The last option is to simply run a slightly slower return rate to minimize the difference in height between the two, but still be able to have the sump usable for ATO, heaters, protein skimmer, etc.

Let me know your thoughts.

 

[DCR]

Yes, you can put the standpipes in the sump and that would allow you to make easy adjustments to the standpipes, but the tank and the sump have to run at nearly the same level and that will not happen except at very low flows. I don't know the size of the tank and how much flow you are trying to circulate. The two 2" drain lines will definitely help. My concern is that you will either end up with very low flow or a large difference in water levels between the two that will cause a substantial drain down of the tank when your return pump stops. I still think you would be better off with some type of overflow in the display and run the sump at 8-12" lower (assuming you have that much room from an elevation standpoint).

 

[jnadz]

Yes, you can put the standpipes in the sump and that would allow you to make easy adjustments to the standpipes, but the tank and the sump have to run at nearly the same level and that will not happen except at very low flows. I don't know the size of the tank and how much flow you are trying to circulate. The two 2" drain lines will definitely help. My concern is that you will either end up with very low flow or a large difference in water levels between the two that will cause a substantial drain down of the tank when your return pump stops. I still think you would be better off with some type of overflow in the display and run the sump at 8-12" lower (assuming you have that much room from an elevation standpoint).

Last pick of your brain before I start to experiment for myself.

The display is a 150 shallow reef that is 64” long by 34” wide. If the sump has a significantly smaller footprint size but more depth, once the power is turned off, the sump level will rise 2-3X faster than the display sinks. Ie, isn’t’ this another consideration and way to control the amount the display will drop?

 

[DCR]

Yes, if the sump has 1/3 the surface area of the display it will rise 3 times more than display will drop when the return pumps stops (and would minimize the level decrease in the display).