Installing my new Sequence 750 pump

[Pablo]

Its been a few months since I have looked into head pressure but I would suggest looking at some online calculators to get the head pressure you have. I inputted some numbers in one for your setup and looks like the head pressure would be about 10ft, but I was going with 6 90 degree elbows, not sure how many you have and high your pumping the water to. The Sequence says max head pressure is 12ft for your pump.

 

[miamicuse]

Its been a few months since I have looked into head pressure but I would suggest looking at some online calculators to get the head pressure you have. I inputted some numbers in one for your setup and looks like the head pressure would be about 10ft, but I was going with 6 90 degree elbows, not sure how many you have and high your pumping the water to. The Sequence says max head pressure is 12ft for your pump.

I agree I need to do some more calculations.

I did one briefly when I was deciding on the pump, and now thinking back, I believe the calculations were not correct in that the rules I used may have been for a submersible pump.

The parameters I had to provide were: Distance from pump to water feature, height from pond water surface to top of water feature etc...

In my case it's an external pump located a bit away from the pond, so I don't know if these parameters need to be adjusted.

For example, let's say the pipe from pump to outlet is 30', which corresponds to about 3' of head pressure. Then the water feature is 5' above the pond water surface so the total is 8' of head pressure, ignoring the elbows etc...but in my case, it's 30' of pipe on the intake to the pump, then 30' of pipe back to the pond, that's 60', I should have used 60' as the pipe length even though the calculator asked for distance of pump to the feature because the pump has to work to pass water from intake to return a total of 60' correct?

As far as the distance from pond water level to the waterfall, even though it's like 5', again I am not sure that the pump is "lifting" just 5'. The intake port can be 2' below pond water level, then it climbs up go over the pond's edge that's 18" above pond water level, then it has to dip back down 16" to below grade so the pipes are buried below a walking path, and when it gets to the pump it rises up another 18" to meet the inlet of the priming pot, then it reverses the path to go back up into the pond below water level and eventually rises up 7' to the top of the water feature. I imagine a pump to lift 5' higher does not have to work as hard as a pump pushing water up then down then up again several times along it's path. I wonder again if the input to these calculator as far as lift height need to be adjusted. In other words, let's say the water feature is right at pond water level, but the pipe goes up 2' down 2' back up 2' down 2', is the lift 0 or 2x3=6 because it has the lift 2' three times?

and that's not even counting all the elbows.

 

[Pablo]

I agree I need to do some more calculations.

I did one briefly when I was deciding on the pump, and now thinking back, I believe the calculations were not correct in that the rules I used may have been for a submersible pump.

The parameters I had to provide were: Distance from pump to water feature, height from pond water surface to top of water feature etc...

In my case it's an external pump located a bit away from the pond, so I don't know if these parameters need to be adjusted.

For example, let's say the pipe from pump to outlet is 30', which corresponds to about 3' of head pressure. Then the water feature is 5' above the pond water surface so the total is 8' of head pressure, ignoring the elbows etc...but in my case, it's 30' of pipe on the intake to the pump, then 30' of pipe back to the pond, that's 60', I should have used 60' as the pipe length even though the calculator asked for distance of pump to the feature because the pump has to work to pass water from intake to return a total of 60' correct?

As far as the distance from pond water level to the waterfall, even though it's like 5', again I am not sure that the pump is "lifting" just 5'. The intake port can be 2' below pond water level, then it climbs up go over the pond's edge that's 18" above pond water level, then it has to dip back down 16" to below grade so the pipes are buried below a walking path, and when it gets to the pump it rises up another 18" to meet the inlet of the priming pot, then it reverses the path to go back up into the pond below water level and eventually rises up 7' to the top of the water feature. I imagine a pump to lift 5' higher does not have to work as hard as a pump pushing water up then down then up again several times along it's path. I wonder again if the input to these calculator as far as lift height need to be adjusted. In other words, let's say the water feature is right at pond water level, but the pipe goes up 2' down 2' back up 2' down 2', is the lift 0 or 2x3=6 because it has the lift 2' three times?

and that's not even counting all the elbows.

I went to law school so I would not have to do math, lol. So I will defer to others here who know more about calculating head pressure. I know there are some youtube videos about calculating it and @GBBUDD and @combatwombat know quite a bit about it. As @GBBUDD mentioned, pumps are good at pushing water but pulling water is a struggle so I am guessing that 30' length from pond to the pump is your issue.
I am sure you will figure it out.
I have my fingers crossed my set up will work, today was a big milestone, started filling the pond. Looks like it will not be done filling today so will have to wait until tomorrow.

 

[combatwombat]

Gonna give a pretty quick reply here as I'm out the door to preschool gymnastics in a moment. Skimmed the thread, and these stood out to me.

I cannot find elbows designed for pressure applications with a curved transition.

You don't need to. The DWV fittings will withstand more pressure than any pond pump could ever throw at it. Believe I've seen reference to 20 PSI, though of course they're not actually rated for any.

If you know of a source for 90 elbows with curved transition that are designed for pressure applications let me know.

You could use schedule 40 electrical sweeps if you must. Lots of koi ponders do that. Expensive. But it's the same stuff, just with an added UV inhibitor.

He suggested that I move the check valve into the pond further closer to the intake port. I might try that.

You absolutely should try that. Probably won't ever successfully prime without that.

Like you said may be the way I have the pipe going up and back down is creating a section that traps air that cannot escape. I may need another opening somewhere to allow priming of that to drive out the air pocket.

Definitely a possibility. Dips in piping can cause air lock.

but I am still skeptical of using gravity drain fittings because when I plumb these lines, I plumbed them without making any decision on the specs of the pump I end up using.

Doesn't matter. DWV welded fittings will withstand anything you can throw at it.

The city water at 50PSI, went through the 30' of pipe with these sharp 90 elbows going down and up and back down and finally pushed water out of the water feature 6' above the pond water level with no issue whatsoever. I thought this pump could do better than city water pressure.

Not sure what you mean with this. 50 PSI is 112' of head. Your pump can only handle 12'. So, your city water pressure is 10x what your pump shuts off at.

Not only it's full of mud, it took quite a bit of strength to push that spring open, and when I did push it open I don't think it was opening enough to let 1-1/2" of volume through. Could this be the reason the pump is not performing? The check valve is stuck and packed with mud?

Think I read you already replaced this? Good. Replace with swing check valve. Too much pressure from spring loaded check valve.

Yes, I have a long stretch of horizontal run, a 33' run from pond to pump

Theoretically, a pump can pull water every bit as well as it can push it. But it doesn't actually work out that way in reality, because there are too many ways to lose prime and create air lock between the water source and the pump. Short runs all headed uphill to the pump is best. If you can relocate pump, recommend it. 30' intake will probably be a source of problems forever. But if you reconstruct intake very carefully, you can make it work. Done all the time with pools. But pool pumps use mega energy and have much higher head pressure.

I should have used 60' as the pipe length even though the calculator asked for distance of pump to the feature because the pump has to work to pass water from intake to return a total of 60' correct?

That's correct.

I am not sure that the pump is "lifting" just 5'. The intake port can be 2' below pond water level,

Lift from end of intake pipe to water surface doesn't matter. It's "free."

then it climbs up go over the pond's edge that's 18" above pond water level, then it has to dip back down 16" to below grade so the pipes are buried below a walking path, and when it gets to the pump it rises up another 18" to meet the inlet of the priming pot, then it reverses the path to go back up into the pond below water level and eventually rises up 7' to the top of the water feature

Another one of those theoretical things. Ups and downs even each other out because the "downs" reduce head. But adding fittings and lots of humps introduces other problems—more head from sharp turns, places for air lock to stop flow.

Good luck!

 

[miamicuse]

I went to law school so I would not have to do math, lol. So I will defer to others here who know more about calculating head pressure. I know there are some youtube videos about calculating it and @GBBUDD and @combatwombat know quite a bit about it. As @GBBUDD mentioned, pumps are good at pushing water but pulling water is a struggle so I am guessing that 30' length from pond to the pump is your issue.
I am sure you will figure it out.
I have my fingers crossed my set up will work, today was a big milestone, started filling the pond. Looks like it will not be done filling today so will have to wait until tomorrow.

I hope yours will work. Because this is no fun, and my wife has been giving me the "why has this taken so long" look LOL.

 

[miamicuse]

Gonna give a pretty quick reply here as I'm out the door to preschool gymnastics in a moment. Skimmed the thread, and these stood out to me.


You don't need to. The DWV fittings will withstand more pressure than any pond pump could ever throw at it. Believe I've seen reference to 20 PSI, though of course they're not actually rated for any.


You could use schedule 40 electrical sweeps if you must. Lots of koi ponders do that. Expensive. But it's the same stuff, just with an added UV inhibitor.


You absolutely should try that. Probably won't ever successfully prime without that.


Definitely a possibility. Dips in piping can cause air lock.


Doesn't matter. DWV welded fittings will withstand anything you can throw at it.


Not sure what you mean with this. 50 PSI is 112' of head. Your pump can only handle 12'. So, your city water pressure is 10x what your pump shuts off at.


Think I read you already replaced this? Good. Replace with swing check valve. Too much pressure from spring loaded check valve.


Theoretically, a pump can pull water every bit as well as it can push it. But it doesn't actually work out that way in reality, because there are too many ways to lose prime and create air lock between the water source and the pump. Short runs all headed uphill to the pump is best. If you can relocate pump, recommend it. 30' intake will probably be a source of problems forever. But if you reconstruct intake very carefully, you can make it work. Done all the time with pools. But pool pumps use mega energy and have much higher head pressure.


That's correct.


Lift from end of intake pipe to water surface doesn't matter. It's "free."


Another one of those theoretical things. Ups and downs even each other out because the "downs" reduce head. But adding fittings and lots of humps introduces other problems—more head from sharp turns, places for air lock to stop flow.

Good luck!

Thank you. I added a check valve at the mouth of the intake pipe, and filled the priming pot. I even added a TEE with a branch facing up where the pipes went up then down, so I can open that and add water there. Does not work. Double, triple checked all joints at the pump and the line for leaks.

But when I connected the intake inlet with a garden hose fed my a small 1/4HP utility pump, and had the Sequence pump OFF, that small utility pump was able to push water through 30' of 5/8" garden hose, then into the 1-1/2" intake line, pushed through all 30' of pipes with all the elbows going up and down into the pump, back out of the pump and going in reverse back to the pond and goes up another 5' to the water feature. That small $99 utility pump was able to drive out all the air and get the job done. I checked the spec of that utility pump and it can do 30' of vertical lift, so may be that's the difference. I was also able to check for leaky joints since both the intake and return lines are under pressure since air leak in the suction line is hard to tell.

I think I just need a pump with a bigger head and a self priming one.

 

[combatwombat]

I think I just need a pump with a bigger head and a self priming one.

Agreed.

 

[combatwombat]

But note that a self priming pump cannot overcome any priming challenge. They have limits.

 

[miamicuse]

Anyone knows of a good online pump head calculator? I checked a few of them and they gave different answers based on same input parameters. I have pond volume, elevation from pond to water feature, length of pipes, number of 90 and 45 elbows.

 

[combatwombat]

Anyone knows of a good online pump head calculator? I checked a few of them and they gave different answers based on same input parameters. I have pond volume, elevation from pond to water feature, length of pipes, number of 90 and 45 elbows.

Which ones did you use? Were the results far apart? The tables on these two pages will get you the correct answer:

PVC Pipes Schedule 40 - Friction Loss vs. Water Flow​

PVC Pipes - Equivalent Length and Pressure Loss in Fittings​

 

[miamicuse]

Which ones did you use? Were the results far apart? The tables on these two pages will get you the correct answer:

PVC Pipes Schedule 40 - Friction Loss vs. Water Flow​

PVC Pipes - Equivalent Length and Pressure Loss in Fittings​

Thanks.

I am referring to the head loss from the length of pipes. In my case I am about 30' each way, 30' of intake and 30' of return so the total run is 60'.

I saw some web sites said to use 1' of loss per 10' of pipe. If I go by that rule, 60' of pipe will lose 6' of head, but this rule has no consideration of flow rate or pipe diameter.

In the chart you provided, looking at 1-1/2" diameter pipe, assuming 20GPM flow rate, the head loss is 2.6ft per 100ft, since I have 60ft, that prorates to 1.56' of loss, which is much less than the 6'.

 

[Pablo]

I hope yours will work. Because this is no fun, and my wife has been giving me the "why has this taken so long" look LOL.

Thanks, I hear you with the "why has this taken so long", I have been working on this since April. A lot of rain here this summer, and always seemed to be on weekends. Pond is filling slowly as it is only 200 gallons an hour, have a thousand gallons in there and have not reached my second level yet.
Glad to see you are getting help from others, they are a great resource.

 

[miamicuse]

Here is what my calculations based on most recent measurements, not knowing which pump I should be getting and yes I have given up on the Sequence 750 model.

(1) DISTANCE FROM POND WATER LEVEL TO WATER FEATURE = 6 FEET

(2) PIPE WORK FRICTIONAL LOSS

I am not sure what flow rate to use, my pond size is 1600 gallons, assuming whatever pump I pick can do better than 1200GPH, and the faster the flow the higher the frictional loss, for 1.5" pipe, at 1200GPH, the loss is 2.6' per 100' of pipe. If I double the flow rate to 2400GPH, the loss increases to 9.4' per 100'. I think may be that's why some tables used 1' of loss per 10' of pipe.

I measured total length of pipe all inclusive intake and return to be about 80 ft long. During my testing of the Sequence pump when I had trouble, I cut the return line where it makes the turn to go into a concrete boulder and up 7' to the water feature just to see if I can get adequate flow back into the pond without any additional lift and even that failed.

Total pipe work frictional loss @ 2.6' per 100', since I have 80' that is 2'. If I go with just 1' per 10' of loss then I have 8' of loss. Let's go with 8' because it's a larger number hence more conservative.

PIPEWORK FRICTIONAL LOSS = 8 FEET

(3) FITTING LOSS

Number of 90 elbows = 22 @ 4 ft each = 22X4 = 88 ft
Number of 45 elbows = 6 @ 2.2 ft each = 13.2 ft
Number of tee flow (run) = 2 @ 3.5 ft each = 7 ft
Number of tee flow (branch) = 2 @ 10.3 ft each = 20.6 ft
Number of check valve = 1 @ 4 ft each = 4 ft
Number of M/F adapters = 3 @ 3.5 ft each = 10.5 ft
Number of straight couplings I didn't count since this could change as I make modifications but let's say 20 @ 1.5 ft each = 30 ft

Adding all that up total is 173.3 ft so let's round it up.

TOTAL FITTING LOSS = 180 FEET

GRAND TOTAL = 6 + 8 + 180 = 194 FEET

Does it mean I need a pump of 194 feet of head to do this? Are my calculations correct?

If so then how does the small $99 utility pump with a max lift of 30ft do it with an additional 30' of 5/8" garden hose thrown in?

 

[combatwombat]

Does it mean I need a pump of 194 feet of head to do this? Are my calculations correct?

No. That’s the total equivalent pipe length.

You have 6’ of static head + about 5’ of dynamic head (200’ of pipe @ 2.6’ of head per 100’ of pipe) for a total of 11’ of head.

 

[Pablo]

I think you have to go back to the issue of having your water source so far from the pump. As @combatwombat calculated the head that would still be within the specs of the Sequence pump. You would never have 194 feet of head, when you look at the PerformancePro specs for all their pumps the biggest pump is 3hp and that lists max head at 94 ft, so you know you are far off in the calculations.
You know the Sequence struggled with the setup but the head is within its specs (what I had calculated yesterday with an online calculator without knowing all the details of your setup was surprisingly close to @combatwombat calculation). I dont have enough experience to know if 30 feet from the source is common, I dont think I have seen that too often when I have researched pond setups. And it could be the combination of the distance and how many 90 degree fittings you have between the water source and the pump. Twenty-two 90 degree elbows seems like a lot, I only have one in my setup so I may not be the norm in that regard. So I guess it might be going back to the drawing board to see if you can re-position the pump.