head pressure calculator

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Weasel1960

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I thought it was 1’ for every 10 horizontal and 1 for every 1 vertical….I have been looking for a good calculator or enough info to do the same without needing a fluid dynamics degree. Would also help if there was a standard for pump specs, like providing a readable performance curve. Many just give you max flow and head and nothing in between.
 
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m.kristoff

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Just curious, when you say "1' per 10' vertical/horizontal" are you saying you are calculating 1' for both vertical and horizontal 10' runs?
I got his from the Ecotech website

The effect of gravity on head pressure is very simple. Every vertical foot of distance the return pump moves water equates to 1 foot of head pressure. The effects of friction on head pressure are more difficult to calculate. Roughly every 10 feet of pipe (horizontal & vertical) through which water is traveling adds 1 foot of head pressure. Additionally, every 90-degree bend adds 1 foot of head pressure.
 

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Frictional head loss is a very complex analysis and the on-line calculators do not include a lot of the fittings we use and consequently will underestimate the head loss. Vertical head loss is always 1:1. I would generally say you can assume 2-4 ft of friction loss for a below tank sump with short return distances if you size your return piping properly. Use 3/4" for up to 300 gph, 1" for up to 600 gph, 1-1/4" f0r up to 1000 gph and 1-1/2" for up to 1500 gph. Be wary of the Neptune paddle wheel flow meters which add a lot of head loss. Except for very small flow rates (less than 400 gph), I would use a 2" if you really feel you need one.
 

Logical_Plan

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Try this calculator:

 
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m.kristoff

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Try this calculator:

this gave me a good ballpark of my plumbing. It calculated that I would be about 50% of my pumps head loss so the +/- is covered.
 

Logical_Plan

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Don't forget that at 50% of the rated head you are giving up a lot of flow. The 3100 GPH, L2 is only going to give you 1300GPH at that head. Might not be enough for your UV target flow rates.

If you run pumps in parallel, the flow is additive to a point for the system head. Where it gets complicated is when you increase minor losses from friction due to velocity. The typical UV closed loop is all friction losses. So parallel pumps may not have true additive flow.
 

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m.kristoff

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Don't forget that at 50% of the rated head you are giving up a lot of flow. The 3100 GPH, L2 is only going to give you 1300GPH at that head. Might not be enough for your UV target flow rates.

If you run pumps in parallel, the flow is additive to a point for the system head. Where it gets complicated is when you increase minor losses from friction due to velocity. The typical UV closed loop is all friction losses. So parallel pumps may not have true additive flow.
I am considering running 2 Cor-20's- have access to 2. They are 2k gph with a 20' head loss. with 2, i can reduce the head loss for both pumps and have redundancy. All depends on how efficiently I can plumb them
 

Logical_Plan

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I am considering running 2 Cor-20's- have access to 2. They are 2k gph with a 20' head loss. with 2, i can reduce the head loss for both pumps and have redundancy. All depends on how efficiently I can plumb them
Head loss is a function of arrangement of plumbing and load. If you connected in series you could get more head from the pumps.

However, since you said redundancy, that implies parallel operation. In parallel operation, flow is additive at a given head. But max head is the max of a single pump.

Two cor20 in parallel operating at 50% of max head will give you 800GPH per pump. Or 1600GPH total if most head losses are static head.

If your system has higher friction losses, you may not be able to get the additive flow.
 

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Logical_Plan

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Makes sense. lets say i run 1 1/4" from each pump to a T and expand to 2" to reduce friction on balanced pumps??
the other option is one for return and the other just for the UV dumping back into the sump. not optimal, but a high turn over
I have been going over plumbing planning and iteration for my system for the past couple weeks. Talking with a few of my mechanical engineering friends, I have come to this generalization.

With the ratings on the pumps in the hobby we generally want them to run dedicated to a system and be sized for that system only.

If you want redundancy, size two pumps at 70% flow at rated head and pipe in parallel. But the check valves and maintenance valves and minor losses due to pipe diameter changes makes this not super practical.

So basically, I have decided to run dedicated pumps for return, recirc skimmer, reactor header and UV. So four pumps on system. Would go to 8 pumps if I wanted redundancy.

Adding multiple loads on a single pump at different heads makes the system curve very complicated. Plus changing one flow, disrupts the flow to all other outlets.

I would try to keep static head as low as possible for UV. Dedicate a pump like COR 20 to it and set flow to desired rate. It seems that flow / contact time is most critical for UV. So if that means back to sump so be it.

If you only have 5' of head by recirculating to sump then with your pumps in parallel you have 1600GPH per pump, 3200ish if in parallel.

Because you are using DC speed control to set flow to match UV you have also reduced minor losses through UV. No gate valve closed loop.

You can now use pump controller to set for protozoa rate 1066 gph ish, if I remember correctly. Or 3200ish for algae control. I believe those were the recommended settings for your UV.

The down side of recirculating to the sump. Less complete turn over of sterilization? Why don't they make that argument about protein skimmers?

Hope that helps. It is all theoretical from an engineering perspective though. I am sure there are a few devil's hiding in the details. But I would buy and build on this basis. Knowing that the cost of changes will be minimal due to reasonable planning.
 
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m.kristoff

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I get what you are saying. As an IT guy, redundancy, control and seeing the picture from a single Pane of glass is key for me. I think pump ratings are like MPG stickers on new cars. Only in the most optimal conditions can that be achieved.

I do own a L2 and 2 COR-20's. The L2 is not a bad pump at all. I'm choosing to go with the COR pumps for the pane of glass and easily control them. The L2 can be controlled for Mobius, but I think Neptune gives more info and can help monitor the ever-changing conditions. Slim buildup, maintenance and performance issues can be seen in Fusion easily. With that being said, I totally agree that the pumps should be matched for the system and also tuned for the system. In my opinion, with all the pumps out there the most "tune-able" is what I am looking for.

I think that the most optimal would be to run the UV inline from one return segregating the pumps per return- 2.
Plan B is to run the UV off of one pump recirculating the sump. My sump is 42 gallons so it can "fairly" effective. If the main pumps go's down I can swap it.
 
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Logical_Plan

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I get what you are saying. As an IT guy, redundancy, control and seeing the picture from a single Pane of glass is key for me. I think pump ratings are like MPG stickers on new cars. Only in the most optimal conditions can that be achieved.
Flow rating on pumps is at 0head. The curve tells you operating point. MPG is a fairish analogy. However, MPG is listed at city and highway driving for normal diving conditions. Pumps rating equivalent analogy would be listing a cars milage at 60 mpg, assuming no wind drag on the car and just enough friction for the wheels to move on the ground with no losses through the power delivery system from engine to wheels. Then looking at curve you would find that you get 30mpg highway and 25 mpg city.
I think that the most optimal would be to run the UV inline from one return segregating the pumps per return- 2.
In this case, if I'm understanding right, you would use 1 cor20 for UV and one for return bypassing the UV, but both go to tank via isolated plumbing? In this case flow through UV is going to be max 1200 GPH ish assuming 8 ish feet of head. If that meets your desires UV flow application, then perfect. Then you have a second return direct to tank, at 1200GPH not through UV?


Plan B is to run the UV off of one pump recirculating the sump. My sump is 42 gallons so it can "fairly" effective. If the main pumps go's down I can swap it.
Attached diagram to try to make sure I am understanding your options.
 

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m.kristoff

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In this case, if I'm understanding right, you would use 1 cor20 for UV and one for return bypassing the UV, but both go to tank via isolated plumbing? In this case flow through UV is going to be max 1200 GPH ish assuming 8 ish feet of head. If that meets your desires UV flow application, then perfect. Then you have a second return direct to tank, at 1200GPH not through UV?
Correct- in theory!

Attached diagram to try to make sure I am understanding your options.
The Diagram you provided; all 3 methods is what I was thinking. looking at it on paper, keeping the L3 or L3 type pump would get the desired effect. Option 2 is more realistic. If I really wanted to toss it against the wall- Add a 2nd UV- one on each return! that is probably unrealistic and bad money spent!!
 
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