What's the best way to get the most efficiency out of a return pump?

[Daniel@R2R]

I've got a Fluval SP6 which has an outlet of 1 1/4". I realize that plumbing should run at the same size as that outlet (reducing it will result in loss of efficiency), but what's the best way to go about splitting it? I'm planning to run the return to two sides of the tank, so what is the best way to do this to keep as much flow as possible?

 

[Breadman03]

I stepped up a pipe size to my wye, then went with outlet size from the wye to the nozzle. Minimal elbows (impossible with my current setup) and keeping the sump as close as possible to the tank, particularly vertically, helps quite a bit.

 

[mfinn]

I've got a Fluval SP6 which has an outlet of 1 1/4". I realize that plumbing should run at the same size as that outlet (reducing it will result in loss of efficiency), but what's the best way to go about splitting it? I'm planning to run the return to two sides of the tank, so what is the best way to do this to keep as much flow as possible?

I would think keeping friction loss to the minimum by running the same size as the outlet of the pump as far as possible. But in this specific case you are using a SP6 as a return pump on a 225 gallon tank. I don't think because of the amount of flow for this pump worrying about efficiency is needed. I'd run the 1-1/4" pvc like a header and do a pair of risers off of it.

 

[Daniel@R2R]

I would think keeping friction loss to the minimum by running the same size as the outlet of the pump as far as possible. But in this specific case you are using a SP6 as a return pump on a 225 gallon tank. I don't think because of the amount of flow for this pump worrying about efficiency is needed. I'd run the 1-1/4" pvc like a header and do a pair of risers off of it.

That's a solid plan. In my case, I could run the 1 1/4 all the way up the back of the tank and split the return in the canopy.

 

[mfinn]

That's a solid plan. In my case, I could run the 1 1/4 all the way up the back of the tank and split the return in the canopy.

Going with a over the top return?

 

[o2manyfish]

Finding the right plumbing parts in 1.25" might be a challenge and a cost. I would convert to 1.5" at the pump - Do all my valves and unions in 1.5" and run to your split point. Then split off to (2) 1" lines. The (2) 1" lines hold more volume than the the single 1.25" output so you won't be restricting any output.

Dave B

 

[KrisReef]

I'm glad you asked. I have an idea but I am not solid in my plumbing physics, so I'm here gleaning tips and knowledge, thanks to all for the answers.

No one has mentioned raising the sump to lower the head pressure, which is generally not practical but a fact that could be helpful to other folks like me who are looking for knowledge and ideas. Good luck with the build!

 

[WVNed]

Make the pipes as big as possible with few turns and as little head as possible.

 

[Dom]

I'm glad you asked. I have an idea but I am not solid in my plumbing physics, so I'm here gleaning tips and knowledge, thanks to all for the answers.

No one has mentioned raising the sump to lower the head pressure, which is generally not practical but a fact that could be helpful to other folks like me who are looking for knowledge and ideas. Good luck with the build!

Yes, I would agree with this idea; the less headroom, the better.

Personally, I like subtle directional changes in plumbing. I'm currently working on a 125 build where my drain and return lines are one solid piece of PVC.

I do this by capping one end of the pvc and filling it with good, 'ole fashioned freshwater gravel. Then I use a heating gun to soften the pvc and make my bends allowing me to be more direct in my water flow path to and from the sump.

 

[Daniel@R2R]

Going with a over the top return?

Yep. I'll have a canopy, so I'm planning to run the returns down both sides of the canopy with 4 total exits (1 half way down on each side and then 2 on the end. The reason is this is a peninsula tank, and I'm trying to add flow on the far end without needing to add an additional powerhead down there on the viewing pane. It's an experiment. We'll see if it works.

Finding the right plumbing parts in 1.25" might be a challenge and a cost. I would convert to 1.5" at the pump - Do all my valves and unions in 1.5" and run to your split point. Then split off to (2) 1" lines. The (2) 1" lines hold more volume than the the single 1.25" output so you won't be restricting any output.

Dave B

Thanks! That's something I hadn't considered. I was planning to go from 1.25" to 1", but I hadn't considered the availability of plumbing parts, so doing 1.5" makes a lot of sense.

 

[mfinn]

Yep. I'll have a canopy, so I'm planning to run the returns down both sides of the canopy with 4 total exits (1 half way down on each side and then 2 on the end. The reason is this is a peninsula tank, and I'm trying to add flow on the far end without needing to add an additional powerhead down there on the viewing pane. It's an experiment. We'll see if it works.

Thanks! That's something I hadn't considered. I was planning to go from 1.25" to 1", but I hadn't considered the availability of plumbing parts, so doing 1" makes a lot of sense.

Have you considered a bottom drilled closed loop system? Great way to add flow to the far end of a peninsula tank.
But dropping the returns at different points with the pump( SP6) makes sense.

 

[flashsmith]

Just my logic, but I do this every day as an owner of an irrigation company. Splitting it off and leaving it at 1.25 will cut your flow in half at the outlets. Think of oversizing a pipe with a set pressure and having too many sprinkler heads on the line. You will have terrible pressure and poor coverage. To fix this use a smaller pipe diameter to increase pressure. The logical solution is to split it right out of the pump to 3/4 and run it up to your outlets from there. Your pump is going to push xxx per hour no matter how you plumb it but if you want flow the sooner you downsize the better. I've only been working with all types of pumps for 25 years so I'm sure there will be plenty who will disagree...lol

 

[RocketEngineer]

While I respect the irrigation expert’s opinion, it is based on pressure systems. A system designed for water at 40-60psi is not going to work quite the same as one working at 5psi because restrictions have an amplified effect. As an example: a 2psi drop because of elbows would have no real impact on sprinklers but would cut in half the flow from your average hobby pump.

Looking at the SP6 specs, I’m seeing 12’ max height which is about 5psi. That tells me this pump is designed for flow, not pressure. As such, minimizing constrictions and bends will be the best approach to obtain the desired flow.

OP: if this is to create flow at the far end of a peninsula, I would look at Melev’s 400G as that’s how his is plumbed and has been running for a long time.

 

[Breadman03]

I would think keeping friction loss to the minimum by running the same size as the outlet of the pump as far as possible. But in this specific case you are using a SP6 as a return pump on a 225 gallon tank. I don't think because of the amount of flow for this pump worrying about efficiency is needed. I'd run the 1-1/4" pvc like a header and do a pair of risers off of it.

When I was researching pump flow ratings, I found that pumps are rated with upsized plumbing from the outlets. I forget the sources because I looked into it maybe 8 years ago.

 

[FSP]

The larger mag drive pumps assume 1.5" pipe minimum. Not sure of any others off the top of my head, but I'm sure many do. It's rarely a bad idea to upsize the outlet as long as it doesn't exceed the diameter of the inlet if being used externally.

In this case, since Daniel is trying to replace a powerhead, it might be a good idea to reduce the exit size (ex: 3/4" reducing elbow or reducing tee on 1" pipe). Larger pipe will reduce friction loss to the tank and the smaller exit will increase velocity.

 

[RocketEngineer]

When I was researching pump flow ratings, I found that pumps are rated with upsized plumbing from the outlets. I forget the sources because I looked into it maybe 8 years ago.

The old MagDrive pumps had this being the case IIRC. Not sure modern ones do or not.

 

[SPS2020]

I'm sure the difference is VERY MINIMAL, but I used 45's in place of 90's.

How to calculate flow loss between 90 and 45 degree fittings Reference: https://www.physicsforums.com/threads/how-to-calculate-flow-loss-between-90-and-45-degree-fittings.934368/

 

[Daniel@R2R]

So this is kind of what I'm imagining right now. (Please don't laugh at my work of art )

Essentially 1.5" out of the pump until it splits to 1" dual lines. The question I have now is do I go with 1" locline and VCA nozzles or do I step down to 3/4" on those outlets?

 

[FSP]

Just looking at VCA's recommended ranges, 3/4" looks about right. I don't have experience with VCA specifically, but eductors need some oomph behind them.

 

[Daniel@R2R]

Just looking at VCA's recommended ranges, 3/4" looks about right. I don't have experience with VCA specifically, but eductors need some oomph behind them.

That's what I'm thinking too. I reached out to VCA with the plan to get their take on it.