DC Pump Output... Pump Curve vs. %Speed

[mstgkillr]

After one of my two COR20 return pumps failed, I did a flow comparison with a replacement return pump (Sicce Syncra SDC 7.0) on my Red Sea S-1000. Unfortunately, I do not have flow sensors, so most of the measurements/comparisons are using a 100% open return drain valve. Also, these comparisons are using dual return pumps with one COR20 and one SDC 7.0.

I was interested to note the following:
1. The COR20 did not output any additional flow past 50%
2. The SDC 7.0 continued to incrementally increase flow all of the way to 100%. It appears that it handles the minor/major piping losses better.
3. With the COR20 anywhere between 50% and 100%, and the SDC 7.0 at 50%, the return drain valve needed to be opened 100% and maintained a perfect level in the overflow, which is maxing out the overflow.
4. The COR20 at 50% and the SDC 7.0 at 40%, with the return drain opened 100% maintained a perfect level in the overflow. Again, maxing out the overflow.

I was a little confused seeing the COR20s max output at 50% and not increase even at 100%. I assume it's due to the S-1000 dual 3/4 return piping restriction.

The SDC 7.0 is LOUD... any idea how dual Varios-4 pumps might perform? I'm wondering if the 3/4" piping is choking out the larger pumps and if a smaller pump would perform similar.

 

[benbalter]

Do you have a neptune apex? You ezyly add a flow sender to it. Then you see 5he real flow rate. Yes it can be done for about 15$. You may be mixing up flow rate and head presser

 

[JNalley]

After one of my two COR20 return pumps failed, I did a flow comparison with a replacement return pump (Sicce Syncra SDC 7.0) on my Red Sea S-1000. Unfortunately, I do not have flow sensors, so most of the measurements/comparisons are using a 100% open return drain valve. Also, these comparisons are using dual return pumps with one COR20 and one SDC 7.0.

I was interested to note the following:
1. The COR20 did not output any additional flow past 50%
2. The SDC 7.0 continued to incrementally increase flow all of the way to 100%. It appears that it handles the minor/major piping losses better.
3. With the COR20 anywhere between 50% and 100%, and the SDC 7.0 at 50%, the return drain valve needed to be opened 100% and maintained a perfect level in the overflow, which is maxing out the overflow.
4. The COR20 at 50% and the SDC 7.0 at 40%, with the return drain opened 100% maintained a perfect level in the overflow. Again, maxing out the overflow.

I was a little confused seeing the COR20s max output at 50% and not increase even at 100%. I assume it's due to the S-1000 dual 3/4 return piping restriction.

The SDC 7.0 is LOUD... any idea how dual Varios-4 pumps might perform? I'm wondering if the 3/4" piping is choking out the larger pumps and if a smaller pump would perform similar.

I have an SDC 6.0 and it's dead quiet at 100%... Are you sure something isn't wrong? Don't get me wrong, I got on Sicce about the XStream SDC's being loud when I first got them, so they're capable of making loud pumps in a market where silent is better, but the SDC's eventually got to a state of silent after about 3 months of break in...

 

[benbalter]

I have an SDC 6.0 and it's dead quiet at 100%... Are you sure something isn't wrong? Don't get me wrong, I got on Sicce about the XStream SDC's being loud when I first got them, so they're capable of making loud pumps in a market where silent is better, but the SDC's eventually got to a state of silent after about 3 months of break in...

Well I run jebao pumps my self. Dirt cheap and very quiet. Pumps do have a max flow rate. When they rate pumps they are measured in the best possible conditions. No head pressure no turns and no lift. So then we install them with a flow meter people go "oh the meter is causing a big flow loss ". No we live in the real world lifting water up 2 to 6 feet up and with turns. So i would say get a flow meter and see what's really going on

 

[JNalley]

Well I run jebao pumps my self. Dirt cheap and very quiet. Pumps do have a max flow rate. When they rate pumps they are measured in the best possible conditions. No head pressure no turns and no lift. So then we install them with a flow meter people go "oh the meter is causing a big flow loss ". No we live in the real world lifting water up 2 to 6 feet up and with turns. So i would say get a flow meter and see what's really going on

Huh? I'm not understanding what any of that had to do with my post saying OP may have a faulty pump if they're saying it's loud... It's a DC pump and only 1 size up from mine... It should be dead quiet...

 

[benbalter]

Huh? I'm not understanding what any of that had to do with my post saying OP may have a faulty pump if they're saying it's loud... It's a DC pump and only 1 size up from mine... It should be dead quiet...

Sorry yes sounds like you have a bad pump

 

[DCR]

Noisy pump issues aside, as an engineer familiar with sizing piping, I can tell you that your 3/4" piping is going to severely limit your flow. I would not expect much more than 250-300 gph from any aquarium pump through a 3/4" return line, regardless of the rated flow of the pump (zero head). You could probably get equal performance from a pump rated for 600-800 gph at zero head. The only advantage of an oversized DC pump is that you may be able to run it at a lower speed for noise reduction.

 

[mstgkillr]

Noisy pump issues aside, as an engineer familiar with sizing piping, I can tell you that your 3/4" piping is going to severely limit your flow. I would not expect much more than 250-300 gph from any aquarium pump through a 3/4" return line, regardless of the rated flow of the pump (zero head). You could probably get equal performance from a pump rated for 600-800 gph at zero head. The only advantage of an oversized DC pump is that you may be able to run it at a lower speed for noise reduction.

It has been a while since I calculated major/minor loses in fluids. I appreciate the reply, but how confident are you in that statement? Are you saying that a VariouS-4 (1050 GPH and max head at 14.7 ft) would perform the same as a Syncra 7.0 (1900 GPH and max head at 16.5 ft) with 3/4 piping?

 

[DCR]

It has been a while since I calculated major/minor loses in fluids. I appreciate the reply, but how confident are you in that statement? Are you saying that a VariouS-4 (1050 GPH and max head at 14.7 ft) would perform the same as a Syncra 7.0 (1900 GPH and max head at 16.5 ft) with 3/4 piping?

The Syncra generates 16 ft of head at 300 gph while the Varios 4.0 is only about 8 ft so you will get some additional flow, but it will come at a price in noise and power consumption. The friction losses in 3/4" piping increase significantly as you go over 250-300 gph. I am just saying that you will be wasting a lot of power to try to get much more than 300-gph by increasing the pump size with the 1900 gph pump. If you want more flow than 250-300 gph, it would be far better to increase your pipe size.

 

[mstgkillr]

The Syncra generates 16 ft of head at 300 gph while the Varios 4.0 is only about 8 ft so you will get some additional flow, but it will come at a price in noise and power consumption. The friction losses in 3/4" piping increase significantly as you go over 250-300 gph. I am just saying that you will be wasting a lot of power to try to get much more than 300-gph by increasing the pump size with the 1900 gph pump. If you want more flow than 250-300 gph, it would be far better to increase your pipe size.

I'm currently running dual Syncra SDC 7.0 pumps at 58% with the main drain of my Red Sea S-1000 opened 100%. Just wondering if dual Varios 4 pumps could produce the same flow (maybe even at a higher run percent). It would be much easier if I had real pump curves to review.