Return Pump Redundancy and Plumbing Questions

[Porpoise Hork]

I'm in the process of setting up a new 75g system and am trying to decide on how to best handle the return pump. I originally selected a single Jebao DCT 8000 to handle the job. The return side plumbing is sized at 1" lines to each top corner of the tank with a pair of loc line 3/4" Y fitting adapters on each side with a pair of random flow tips and fan tips on each side. The single pump is more than capable of handling the total flow needs of the tank, but I have been concerned with the possibility of what to do in the event of a pump failure if I am out of town or something, so the thought of adding a second return pump came to mind.

The sump I have has a rather small pump return section ( Precision Marine R24) and the DCT 8000 just barely fits in there without the base stand attached, and it does have space to add a second one, but would be rather tight. I looked at smaller sized pumps but the pump housings are the same size for the 6000 and 8000 series so I figured just get another 8K and throttle them both way down.

Now that that's out of the way here is where I am wondering how to plumb them in. If I do decide to run twin return pumps, should each be separated so they run independently of one another, OR can I join them together after the check valves, ball valve, and accessory manifold (only one return line would have this). I am thinking that if I match the flow settings on each pump and tie them together to a single line before splitting back out it would ensure that both returns get equal flow and will continue to flow if one of the pumps fail. Also that if one does fail the installed check valve just after the pump will close and prevent reverse flow into the sump. Is this a possible setup, or would it create too much head pressure even with the pumps throttled down to say 25-30%? Or would it be best to keep each return line separated instead?

 

[Breadman03]

Just run one, IMO. Set them both up with unions so that you can swap them out easily if needed.

 

[Greybeard]

Redundancy is a good thing... one point I might make on your plan... Buying a higher quality pump, one with a well deserved reputation for long life, might be a better choice than buying two Jebao pumps. When I re-entered this hobby after a decade away, I bought a Jebao return pump, and a Jebao wave pump. The wave pump died after 4 months, the return pump lasted 6. I know, some folks have good luck with them, but I'll not be buying any more Jebao pumps.

If you do go with 2 pumps, I'd recommend you _not_ join the returns. If you do, and one pump goes down... much of the water being pumped by the 2nd pump is going to choose the path of least resistance, and go DOWN to the disabled pump, without ever having passed through the display. Depending on exactly how the plumbing runs, it might even be ALL of the 2nd pumps water, exiting into the sump through the 1st pump's intake. Gravity is going to make that water run down hill as long as an avenue is open to it... no way around it.

I'm all about redundancy, eliminating single points of failure, etc. I have one return pump... but I have a high water level switch in my sump. If the return pump goes down (and I still have power), I know about it... because I get an email letting me know that switch tripped. The same sensor also shuts off my skimmer, so that it doesn't flood. With wave pumps in the tank to circulate water, having the return pump down for a few hours isn't going to do any harm... Good enough for me.

 

[Porpoise Hork]

@Breadman03 Running a single pump would make it much more simple, and all my fittings are true union so if needed any section of pipe can be removed for service if needed.

@Greybeard The reason I selected the jebao DCT pumps is cost factor as I am on a rather tight budget and they do seem to have a fairly high reliability rate. Granted the DCT pumps are completely different, but I have been running a pair of their PP-4's linked together on my 40g for over a year with no issues at all. I have been looking at other options for DC return pumps but unfortunately have not found any capable of the flow rate I need in the price I can afford, at least for now. I am open to upgrading to a more reliable set of pumps later on down the road.

As for the dual pump plumbing, I intended to install a check valve on each return line about 3" above the pump outlet before the lines made the turn and into ball valves, so if one pump did fail it would close and prevent any flow from returning back through the failed pump.

 

[Finhead]

I would get the latest version if your buying new. The DCP are the lastest version, I run the DCP8000 and have had zero issues with it. If you search around it actually has better reviews and less failure than some of the higher end DC pumps out there.

 

[Greybeard]

I intended to install a check valve on each return line about 3" above the pump outlet

This would limit my primary concern with linking the outputs... I might mention that I don't trust check valves... I've had them fail one too many times, but yes, as long as they check valves were operating properly, this would work.

I understand budget concerns... I'm running a Current USA eFlux pump, with excellent results, so far.

 

[Porpoise Hork]

Thank's everyone for all the input.

@Finhead I looked at the DCP's and initially decided against them because they were the new design and initial reviews were not as favorable as the DCT pumps. Also it does appear that the DCP's are slightly larger than the DCT's and that presents an issue as in order to get the pump I have in the sump the foot mount has to be removed and it is still a very tight fit. So much so impeller housing cover comes in contact with the walls of the sump.

@Greybeard I'm liking the Current pump. It looks like it has a slightly smaller foot print at 3.5" compared to the 4.1" of the Jebao DCT, and can be setup as an external pump as well. If possible can you see if this this measurement is for the feet of the pump, or of the pump housing itself? I'd like to avoid drilling the sump as it would add another possible area for leaks to run it externally but I decide to go with this pump and it doesn't fit the sump chamber I may not have a choice.

 

[Greybeard]

Hm. I'm afraid I'm not really willing to pull the pump and measure it. Current USA shows the 1900 at 6.4" x 3.5" x 4.7". There isn't really a base, just a set of silicone rubber bands that go around the pump housing with small 'feet' molded in. I don't think they expand those dimensions at all, other than raising the pump by a half inch or so. The strainer, if you use it, does expand the length by an inch and a half or so.

Their 'loop' network seems like a good idea... I don't really know, as I only have the one Current USA device. I considered their wave pumps, but ended up going with AC pumps from Rossmont. Since I like long run times on my flow pumps, just plugging AC pumps into my controller made more sense to me. I've only had it for 8 months, but so far, it's been dead reliable, and it's virtually silent.

 

[Porpoise Hork]

LOL, I wasn't suggesting that you pull the pump to measure it just. I was looking for more of what you mentioned about the feet being smaller than the housing. So your description pretty much let me know what I was curious about. I'll definitely take a closer look at this pump as an alternate to the Jebao.

 

[Centerline]

If you score a second pump I would keep it in the box until you need it. Exposing anything to saltwater slowly eats it. Hate to find out 4 years down the road that the impeller in you standby pump is froze I'm place.

 

[ca1ore]

I go with the 'have a pre-unioned spare on hand'. Doesn't help if you are away and there's nobody to do the swap of course; but I use long tenured external pumps and the last time I had one fail was ..... well, never actually.

 

[Finhead]

Thank's everyone for all the input.

@Finhead I looked at the DCP's and initially decided against them because they were the new design and initial reviews were not as favorable as the DCT pumps. Also it does appear that the DCP's are slightly larger than the DCT's and that presents an issue as in order to get the pump I have in the sump the foot mount has to be removed and it is still a very tight fit. So much so impeller housing cover comes in contact with the walls of the sump.
I'll third the spare for a quick swap, I have will be getting a spare in the next few weeks as well. Have a spare Crossflow sitting here if I ever need it as well.

@Greybeard I'm liking the Current pump. It looks like it has a slightly smaller foot print at 3.5" compared to the 4.1" of the Jebao DCT, and can be setup as an external pump as well. If possible can you see if this this measurement is for the feet of the pump, or of the pump housing itself? I'd like to avoid drilling the sump as it would add another possible area for leaks to run it externally but I decide to go with this pump and it doesn't fit the sump chamber I may not have a choice.

Ah that wasn't my findings butwhatever you feel comfotable with. The new impeller is a pretty big upgrade as well as the controller is supposed to be a better more refind unit.

 

[Terrp]

I've done all three options over the years: (1) a single pump with spare on hand, (2) two pumps with independent return lines, and (3) two pumps feeding into one return line.

I travel up to 2 weeks at a time, so the spare-on-hand option no longer works for me, no matter how reliable the pumps are.

The two pumps with independent return lines approach works, but keep in mind that you'll likely want a check valve on each line, since some or all of the water from the tank might go down the other return line, depending on your setup. If you tee off your returns for reactors, skimmer, fuge, etc., or if you only have 1 return line, than this approach won't work for you without modifying your setup.

I'm currently using 2 pumps into a single line. I was forced to use this approach, since my Reefer 750 XXL only has one return line. You need check valves on each line for this approach as well. I used wye check valves for my setup. I originally had these just above the pumps, but when I upgraded the plumbing for more flow, I attached each to a union directly attached to each pump so that they are below the top of my sump. When opening the wye check valves, water leaks out, so best to have them where the water will drip into the sump.

For a dual-pump approach to fail, both pumps OR one pump and the other check valve would need to fail at the same time. That's much better redundancy than the spare-on-hand approach.

Note that the disadvantage of joining two pumps into one return line is that it isn't very efficient for flow. In my first attempt at this setup, two pumps running at 100% only produced 50% more flow than one pump running alone. I recommend oversizing the return lines wherever possible, and oversized DC pumps allow you to fine tune the flow perfectly. Also, I recommend using a wye fitting to connect two lines rather than a tee fitting, as the wye seems be more efficient. BRS only carries tee fittings last I checked, so I got mine off the internet.

With my travel schedule, redundancy and failover options are key. In my current build, I've made that a priority and have a number of features included. I'm planning to start my own build thread when I get time... Will be sure to highlight the redundancies and to detail the plumbing when I do.

 

[Porpoise Hork]

@Finhead Thenks for the info. It has been 3-4 months since I looked at the DSP pumps so I'll take a look at them again. The good thing with ordering them off Amazon is the ability to return it if it wont work for my setup.

I've done all three options over the years: (1) a single pump with spare on hand, (2) two pumps with independent return lines, and (3) two pumps feeding into one return line.

I travel up to 2 weeks at a time, so the spare-on-hand option no longer works for me, no matter how reliable the pumps are.

The two pumps with independent return lines approach works, but keep in mind that you'll likely want a check valve on each line, since some or all of the water from the tank might go down the other return line, depending on your setup. If you tee off your returns for reactors, skimmer, fuge, etc., or if you only have 1 return line, than this approach won't work for you without modifying your setup.

I'm currently using 2 pumps into a single line. I was forced to use this approach, since my Reefer 750 XXL only has one return line. You need check valves on each line for this approach as well. I used wye check valves for my setup. I originally had these just above the pumps, but when I upgraded the plumbing for more flow, I attached each to a union directly attached to each pump so that they are below the top of my sump. When opening the wye check valves, water leaks out, so best to have them where the water will drip into the sump.

For a dual-pump approach to fail, both pumps OR one pump and the other check valve would need to fail at the same time. That's much better redundancy than the spare-on-hand approach.

Note that the disadvantage of joining two pumps into one return line is that it isn't very efficient for flow. In my first attempt at this setup, two pumps running at 100% only produced 50% more flow than one pump running alone. I recommend oversizing the return lines wherever possible, and oversized DC pumps allow you to fine tune the flow perfectly. Also, I recommend using a wye fitting to connect two lines rather than a tee fitting, as the wye seems be more efficient. BRS only carries tee fittings last I checked, so I got mine off the internet.

With my travel schedule, redundancy and failover options are key. In my current build, I've made that a priority and have a number of features included. I'm planning to start my own build thread when I get time... Will be sure to highlight the redundancies and to detail the plumbing when I do.

Thank you for the input, very useful information. My goal with running twin pumps into one line then back to two returns was to ensure that in the event of a single pump failure the flow characteristics in the tank would not be significantly impacted as the second pump could be adjusted to compensate for the reduced flow until the failed unit can be replaced. I wasn't looking to double the flow output as I planned to be able to run both pumps at 25-35% of their max rated output and then if one fails I can crank the other one up to restore flow. That's why I decided on the 8000 series Jebao as it is more than capable of handling the output needed by itself and still have more in reserve.

Nice tip on the wye fitting as opposed to the T-Fitting. I had not considered using one of those but I can see how this type would greatly improve flow and reduce turbulence and stress on the pumps. I did find an awesome online vendor for PVC fittings and valves that is far cheaper than anyone else out there. www.pvcfittingsonline.com/ I was able to get all the fittings needed for my build in sch 80, including true union ball valves, and check valves for less than 1/2 shipped than just the fittings would have cost at Home Depot. Very reasonable shipping rates and I have always received my order within a couple days.