Apex reporting return flow at 250gph with a Vectra S1 return pump

[PigFarmer]

So are these Vecta pumps extremely over rated or do the flow meters restrict flow by a fair amount?

I just setup my new Vectra S1 with a 1in flow meter on a reefer525 and apex is reporting a max GPH of 252... This flow report on a 140gal tank is causing me concern. I've adjusted the FMM to 1in in the settings etc. The actual tank return is 3/4in thus my 1in flow meter is adapted down to 3/4in also and I'm wondering if this also is of issue?

Thanks for any help!

 

[Bob Escher]

Your reduced 3/4 is reducing it, plus any elbows, any 90 degree returns, any 45 degree returns
It all reduces it. I have a Reef Octopus Octopus S6 that I run at a supposedly 75% and my APEX says it is getting 275GPH return but I do have two 90’s going into it and a couple others after it so I know I’m getting a very reduced return. I understand that.
Do not expect it there is too many variables
If you were to run a very straight pipe 8 inches in and 8 inches from the APEX you may get the results your expecting ( other opinions expected here as well)

 

[andys]

You should have a M1 on a 525xl. When I had my 525 I ran it with a M1 wide open

 

[PigFarmer]

Your reduced 3/4 is reducing it, plus any elbows, any 90 degree returns, any 45 degree returns
It all reduces it. I have a Reef Octopus Octopus S6 that I run at a supposedly 75% and my APEX says it is getting 275GPH return but I do have two 90’s going into it and a couple others after it so I know I’m getting a very reduced return. I understand that.
Do not expect it there is too many variables
If you were to run a very straight pipe 8 inches in and 8 inches from the APEX you may get the results your expecting ( other opinions expected here as well)

Right on, I kinda figured this.. I'm using the soft hose, so I don't have any corners etc but I do have the 1in flow meter adapted down to 3/4 barbed hose connectors on both ends... Well at least I can still get an alert if my pump dies lol. Expensive lesson

 

[Hitman]

Seems to be a lot of people reporting very very low actual flow numbers with all the Vectra pumps.
It seems they don’t like any plumbing under 1 1/4”

 

[PigFarmer]

You should have a M1 on a 525xl. When I had my 525 I ran it with a M1 wide open

Geez, the GPH of the S1 is listed at 1400gph, I figured even this was more than enough

 

[gcarroll]

Geez, the GPH of the S1 is listed at 1400gph, I figured even this was more than enough

It might have been if you had 1" plumbing all the way to the top. Low voltage DC pumps typically don't like to be restricted. Its a product of their low wattage. Based on the flow chart, if correct, the Vectra S1 should be doing 250 gph at 10' of head. figure you have a natural 5' head + elbows and couplings. Any additional head will be attributed to the reduction of pipe size.

Say you used a Mag 12, although it is rated only to 1200 gph, it would provide 600gph to the same 10' of head. Even a Mag 9.5 rated at 950 gph would do 400 gph at 10' of head. The big difference is that the Mag will probably pull 50 - 60% of it's rated power at 10' of head so the energy savings advantage will not be much of a benefit when using DC.

 

[PigFarmer]

so basically AC pumps over DC for return pumps.... marketing got the best of me yet again lol

 

[Breadman03]

so basically AC pumps over DC for return pumps.... marketing got the best of me yet again lol

Maybe. Watts, flow, and sound levels should all be considered and a decision made from the combination.

 

[gcarroll]

so basically AC pumps over DC for return pumps.... marketing got the best of me yet again lol

Not at all, but people need to be mindful as to the disadvantages of the DC pumps. For many the advantages far outweigh the disadvantages.

 

[DCR]

The 3/4" piping is really restricting the flow, regardless of whether you are using AC or DC.

 

[gcarroll]

The 3/4" piping is really restricting the flow, regardless of whether you are using AC or DC.

The output of the Mag 9.5 to Mag 18 is 3/4". It's on a pump by pump basis. You can't just pick a pump without looking at all factors. That is all I'm trying to say. Define the job you are trying to do and pic a pump that is right for that job.

I'm not saying that the Mag is the right pump for the job. It was just the pump I used for the example.

 

[alton]

3/4" barbed fitting is more like 1/2" internal diameter, I think it is .562? Use 1" Flexible PVC and PVC fittings.

 

[DCR]

The output of the Mag 9.5 to Mag 18 is 3/4". It's on a pump by pump basis. You can't just pick a pump without looking at all factors. That is all I'm trying to say. Define the job you are trying to do and pic a pump that is right for that job.

I'm not saying that the Mag is the right pump for the job. It was just the pump I used for the example.

I don't disagree with you on pump selection, but I would add that the pipe size is just as important as the pump selection in getting the desired flow.

In your analysis of the Mag 9.5 and Mag 18, you are assuming that the 10 ft of observed head loss is constant with changing flow, which is not true. The elevation head is constant at 5 ft, but the frictional head loss goes up with square of the flow rate. If the OP is experiencing 5 ft of friction loss at 250 gph with his 3/4" piping as you correctly suggest, then the frictional loss at twice the flow (500 gph) in the same piping system will be 4 times 5 ft, or 20 ft. He would need a pump that can deliver 500 gph at 25 ft of head which neither Mag or most any other aquarium pump will do. I am just using 500 gph as an example here, but my point is that the discharge piping needs to be debottlenecked in order to get significantly more flow, rather than replace the pump.

Also it is not correct to assume that if you just match the discharge pipe on the pump, you have the correct line size. Most pumps have restricted high velocity discharge nozzles for efficiency, and the discharge piping needs to be increased at least one and sometimes two sizes to avoid excessive frictional losses.

 

[gcarroll]

I don't disagree with you on pump selection, but I would add that the pipe size is just as important as the pump selection in getting the desired flow.

In your analysis of the Mag 9.5 and Mag 18, you are assuming that the 10 ft of observed head loss is constant with changing flow, which is not true. The elevation head is constant at 5 ft, but the frictional head loss goes up with square of the flow rate. If the OP is experiencing 5 ft of friction loss at 250 gph with his 3/4" piping as you correctly suggest, then the frictional loss at twice the flow (500 gph) in the same piping system will be 4 times 5 ft, or 20 ft. He would need a pump that can deliver 500 gph at 25 ft of head which neither Mag or most any other aquarium pump will do. I am just using 500 gph as an example here, but my point is that the discharge piping needs to be debottlenecked in order to get significantly more flow, rather than replace the pump.

Also it is not correct to assume that if you just match the discharge pipe on the pump, you have the correct line size. Most pumps have restricted high velocity discharge nozzles for efficiency, and the discharge piping needs to be increased at least one and sometimes two sizes to avoid excessive frictional losses.

So my question to you is...
How close to real life is you example?

If the Vectra is putting out 250 gph on his system in its current plumbing, that lines up at 10’ of head.

If you then put a Mag 9.5 on the tank, with the exact same plumbing, what would it do? I ask because the chart at 10’ says it will do 450 gph. If it won’t do that what will it do? You aren’t suggesting that it will do less than 250 gph are you?

 

[DCR]

So my question to you is...
How close to real life is you example?

If the Vectra is putting out 250 gph on his system in its current plumbing, that lines up at 10’ of head.

If you then put a Mag 9.5 on the tank, with the exact same plumbing, what would it do? I ask because the chart at 10’ says it will do 450 gph. If it won’t do that what will it do? You aren’t suggesting that it will do less than 250 gph are you?

I estimate the Mag 9.5 would operate at about 300 gph at 11.4 ft of head and the Mag 18 would operate at about 385 gph at 15.3 ft of head on this system. This is based on linearizing the tabular performance information on the Danner website. I also adjusted the Vectra head from 10 ft to 9.5 ft at 250 gph so that the frictional loss is 4.5 ft. This assumes the 5 ft elevation difference is valid, but the big assumption in this is that the Vectra is actually operating on its published performance curve, which I think many people here would question. Estimating the discharge head and frictional resistance using a predicted pump performance curve and flow meter instead of a pressure sensor introduces a lot of uncertainty. I do think it is generally impractical to get more than 300-400 gph using 3/4" pipe. I would recommend using 1" for 300-600 gph, 1-1/4" for 600-1200 gph, 1-1/2" for 1200-1800 and 2" up to about 3000 gph to keep frictional losses to a reasonable level. I also suspect the OP's flow meter is adding a lot of the observed frictional head loss in this system.

To get 3X flow (420 gph) on his existing system, the OP would need a pump that can deliver 420 gph at 17.7 ft. To get 5X flow (700 gph), a pump that could deliver 700 gph at 40 ft of head would be required. It will be far more efficient to change the piping. The 3x flow (420 gph) can likely be achieved with the S1. To get to 5X, a larger pump will likely be required

 

[ca1ore]

I believe that all of the vectra pumps are rated based on the native 1 1/2" in and 1 1/4" out. I did some testing with my M1 when I first got it three years ago and found it to perform poorly against back pressure ..... including using the awful blue collar connecters. I've maintained native plumbing in and out, and on my closed loop I get close to advertised flow.

I have not used any other DC return pumps, so cannot say if they are similar. Anytime I need to push against pressure I use an appropriate AC pump.

 

[ca1ore]

The interesting thing to me when trying to compare efficiency is that it appears to be more a function of design than AC versus DC. For example, PanWorld make two versions of their model 50 pump. The 50PX does 590 gph at zero back pressure; the 50PX-X does 1,100 gph at zero back pressure. Both use about the same amount of power (90 watts). Clearly the latter pump is more efficient …. or is it? I have both at home and the only differences are in the volute and impeller. If you need a pump to push water through a chiller, for example, the PX-X is the far better choice, but it quickly craps out when asked to pump up against pressure where the PX is the better choice. It's about design. My limited experience with DC pumps suggests that they are designed for flow - so in a low pressure application they will outperform one designed for pressure. Most AC pumps seem designed for pressure. My big tank uses a Panworld 250, and it is an energy hog (390 watts). But, it gives me almost 1,600 GPH against 14 feet of total head pressure. Is there a DC pump that would give me that for less wattage? Or without spending what I would consider to be an absurd $$ for a pump. Oh, I need decade reliable too LOL. Sorry for the tangent.

 

[gcarroll]

Not sure how long it would take to you to recover your return on investment. I guess it really depends on the price you pay for electricity there in CT. Here in California, the Abyzz pump could could save you an addition $50-75/month. so it would only tanke you 3 years to recover the costs.

 

[gcarroll]

I estimate the Mag 9.5 would operate at about 300 gph at 11.4 ft of head and the Mag 18 would operate at about 385 gph at 15.3 ft of head on this system. This is based on linearizing the tabular performance information on the Danner website. I also adjusted the Vectra head from 10 ft to 9.5 ft at 250 gph so that the frictional loss is 4.5 ft. This assumes the 5 ft elevation difference is valid, but the big assumption in this is that the Vectra is actually operating on its published performance curve, which I think many people here would question. Estimating the discharge head and frictional resistance using a predicted pump performance curve and flow meter instead of a pressure sensor introduces a lot of uncertainty. I do think it is generally impractical to get more than 300-400 gph using 3/4" pipe. I would recommend using 1" for 300-600 gph, 1-1/4" for 600-1200 gph, 1-1/2" for 1200-1800 and 2" up to about 3000 gph to keep frictional losses to a reasonable level. I also suspect the OP's flow meter is adding a lot of the observed frictional head loss in this system.

To get 3X flow (420 gph) on his existing system, the OP would need a pump that can deliver 420 gph at 17.7 ft. To get 5X flow (700 gph), a pump that could deliver 700 gph at 40 ft of head would be required. It will be far more efficient to change the piping. The 3x flow (420 gph) can likely be achieved with the S1. To get to 5X, a larger pump will likely be required

Thanks for your explaination. I can't argue with you calculations as it is beyound my understanding. I would however to see a comparison with other pumps on these Red Sea tanks. Sound like based on your calculation no one would be able to get 500 gph using their plumbing.