2 return pumps one return line

[Don Lidtke]

My plan is to run two pumps but have one directly tied to the return line and the second pump running the manifold. Since I am planning on running the Red Sea XXL with only one return line and I am still trying to figure out the best way to join the two pumps to the one return line. I am looking forward to seeing the suggestion here.

 

[JoshH]

What size of pipe were you planning on running for the return? I might have missed it

 

[Engloid]

I can say that I have 30yrs experience doing piping in industrial environments....and I can tell you that it's not a good idea at all to run two pumps like this. If you want a backup, just add a second one and a valve at each one so you can just turn a couple valves and have the backup running. The reason you don't want to run two at once "in case one fails" is because if one fails, the other one will just push water backwards through it.

 

[Daltrey]

My ecotech vectra pump lets me know if a failure happens. Then I can hook up my cheap jebao backup until I can get it fixed. It takes me all of five minutes to change out the return pump with the backup.

 

[Mrx7899]

My ecotech vectra pump lets me know if a failure happens. Then I can hook up my cheap jebao backup until I can get it fixed. It takes me all of five minutes to change out the return pump with the backup.

That's good if your home but if your out of town doesn't help much

 

[michaelrc51]

This is exactly what I wanted to do with my Dreambox, that I am selling[emoji4].

Here’s my idea.....
I would go from 2-2” lines to a 2.5” Y and then the opposite up at the tank. Right before they Y together I would put check valves and then 2”-2.5” fittings, unless I could find a Y that was 2-2” in and 1-2.5” out. I was also going use FMMs in both 2” lines and with both RD3 150watt pumps running at say 45%, if one goes down the check valve will close and cause the FMM to see less flow. Then use the Apex to kick the single running pump up to say 90% and shut down the failing pump completely. I would only use 45* fittings and a Y, not any 90* or a T.

This is why I had my Dreambox constructed the way I did, with 2 RD3 150watt pumps and 2-2” outlets. One pump can handle more than enough for the 300 total gallons. It’s more expensive but I thought this was the only way it could be truely redundant.

I am thinking in theory this would work. Any thoughts?

 

[pluikens]

I can say that I have 30yrs experience doing piping in industrial environments....and I can tell you that it's not a good idea at all to run two pumps like this. If you want a backup, just add a second one and a valve at each one so you can just turn a couple valves and have the backup running. The reason you don't want to run two at once "in case one fails" is because if one fails, the other one will just push water backwards through it.

Agreed, that's why my suggestion included swing check valves before they wyed together.

 

[Engloid]

Agreed, that's why my suggestion included swing check valves before they wyed together.

But, if they are both turned on, both check valves are open...and the pumps are still pushing against each other.

 

[Engloid]

Agreed, that's why my suggestion included swing check valves before they wyed together.

But, if they are both turned on, both check valves are open...and the pumps are still pushing against each other.

 

[pluikens]

Yes, which is why I would only run one at a time. Each pump on is own could meet the flow demands for the tank. The backup would only be used after a failure in the primary was identified. Power to the primary shut off and the backup turned on.

 

[Rjramos]

IMHO, there are many ways to save your tank if the only pump fails. Dual pumps as mentioned Wyeing into 1 return would require a much larger return to accommodate the rated capacity of both pumps. 1 pump running and the other one on emergency standby would require check valves that anyone in this hobby long enough would tell you, “they fail”, with all the tiny limpet and other crusty critter shells. I find external A/C pumps like Iwaki, Little Giant, to be most reliable. They are not submitted to constant submersion causing encrusting coralline and organisms, or calcification on components. Secondly, when something does jam up in the impeller, it is the A/C pump that better overcomes it. Strainers or sponges are a must on all pump intakes. A backup to a display tanks main pump is as simple as a powerhead or wave maker in the display itself. This should keep everything alive until you can correct the pump problem. [emoji1303]

 

[pluikens]

I'm not so concerned with my return pump for flow in my tank as much as getting heated water that has been through filtration back to my display. My tank cools in a matter of hours in the winter when I'm away from the house. If I was notified that my tank was below temperature, I could remotely turn the heat in the house up but that would only slow down the cooling. I guess for redundancy I could add a heater to my display but I feel that discussion is off topic in this thread.

 

[michaelrc51]

Yeah, if they’re both coming out of the tank at 2” lines, the pipe size after they join would have to be 2-1/2” or 3”. I haven’t done the math on the size but 2-1/2” provides a lot more volume than a 2”.

But, I don’t see how the pumps would be working against each other? If you’re using a T, I could see. But using 45* fittings and a Y everything will flow in the same direction. As long as the diameter is right, I don’t think they’ll fight each other.

 

[Daltrey]

Ok, Now you have me worried about what will happen if I'm out of town for a while and my return pump fails. I have a backup plan for every situation except this.

The problem is like you say the tanks temp will fluctaute since the heaters are in the sump. My room is heated and cooled using a separate mini split from the rest of the house so I do have that advantage.

I run two eheim jager 250 watt heaters in my sump. One acts as the backup and only comes on in an emergency. From now on if I'm going to be out of town for a few days to a week I'm just going to place the backup heater into the main display until I get back from out of town.

Thanks for finding the only weak spot left in my setup. That should cover everything.

Let me know what you decide to do as I may add a second pump also.

 

[airmotive]

But, if they are both turned on, both check valves are open...and the pumps are still pushing against each other.

They’re not really pushing against each other.
Here’s a good article explaining pump curves and how to understand pump curves in designing a fluid system. (There’s also an imbedded link on pump curve basics).
https://blog.craneengineering.net/operating-centrifugal-pumps-in-series-or-parallel

Personally, if you absolutely need two pumps to sleep at night, I’d go series, with an AC pump being #1, driving through a smaller variable speed DC. (The AC pump is acting as a feed pump for the DC pump)
Remember that you’re ADDING the head pressure when running in series. Don’t blow out your return pipes.
Use the DC to control your final pressure. Either pump by itself can, at the very least, circulate water. Centrifugal pumps are effectively hallow; water can flow relatively freely though them when they’re not running.

Or just drop a small heater in your DT when you travel. One that’s too small to cause a lot of trouble if it fails high, but big enough to keep temps just warm enough if there’s no return pump. Also remember that simply pumping water within the aquarium also adds heat.

 

[PaulK]

If all you’re worried about is heat, you can keep the heater in the overflow (low enough so that it stays submersed during pump/power failures) instead of the sump. Then if the return pump fails the heater would still heat the water in the overflow box, and that would warm up the surrounding tank water. I used to run my heater like this on a cube with a small sump. Worked fine.

 

[PaulK]

Also I wonder how common is it for a return pump to fail? I’ve been keeping reefs on and off for about ten years and have never had a return pump fail while running. I have had some refuse to start back up after I turn them off, but I’ve never had one just die while running.

 

[Saltwaterjeff]

The only thing I can add and that i dont think I heard come up would be a backup generator transfer switch. They are not that hard to install and if you are in an area that gets frequent power outages, it is a great investment. However, if your out of town you would need to have someone that could hook it up and turn it on for you.

As for two pumps running would it also not depend on the flow rate of each pump? To have both running at the same time you would have to use a valve to slow the flow down anyways. maybe I am not getting the idea of two pumps running at the same time. Someone needs to invent a backflow preventer that acts as an ON/OFF switch. That way if it closes due to failure the other can turn on.

 

[michaelrc51]

The only thing I can add and that i dont think I heard come up would be a backup generator transfer switch. They are not that hard to install and if you are in an area that gets frequent power outages, it is a great investment. However, if your out of town you would need to have someone that could hook it up and turn it on for you.

As for two pumps running would it also not depend on the flow rate of each pump? To have both running at the same time you would have to use a valve to slow the flow down anyways. maybe I am not getting the idea of two pumps running at the same time. Someone needs to invent a backflow preventer that acts as an ON/OFF switch. That way if it closes due to failure the other can turn on.

My idea would use Apex FMM on each individual return line before they Y into 1 large return line. If one FMM were to see say a 20% decrease in flow I would use the Apex to shut that pump’s outlet off and increase the flow of the opposite pump to the necessary flow. Also, when the power is cut to the 1 pump the check valve will close keeping flow going towards the tank.

 

[Engloid]

Yes, which is why I would only run one at a time. Each pump on is own could meet the flow demands for the tank. The backup would only be used after a failure in the primary was identified. Power to the primary shut off and the backup turned on.

Makes sense...if you have the space and money. I have a backup pump but don't have room for another one in my sump.