HelifaxNZ Posted September 7, 2005 Report Share Posted September 7, 2005 Does anyone know how you figure out what size power pump you will require in your sump to feed the water back up to your tank? I hear people saying for example that they are getting a max. flowrate of 300GPH to their sump and I'm amazed at how they can work that out. Cheers Helifax Quote Link to comment Share on other sites More sharing options...
Pies Posted September 7, 2005 Report Share Posted September 7, 2005 Hi Helifax Its easier than you think. You can find graphs for most pumps to find out how much water they pump at a given head height. E.g. an Ehiem 1262 may have a flow of 2200 lph at 4 foot head. so if you are pumping water up 4 feet, its a safe bet you are getting approx 2200 litres per hour through the sump. 4 major things to consider when buying a sump return pump: 1 - How high do you need to pump? Some pumps arn't presure rated, so they work great at circulation (e.g. power heads) but are no good for anything else. In my situatuon I am pumping about 10 feet, which ruled out most of the hobby pumps (ehiem etc). 2 - Reliability! Pumps can be expensive. However in the marine/sump environment you will problably have your heaters, skimmers etc in the sump. So if your return pump fails, you tank will not get heated, filtered or even oxygenated. The return pump is one of the most important pieces of my system, I belive its the single most important piece of equipment. 3 - Circulation. How much water do you need to put through the sump? Depends, but the general rule is as much as possible. You return pump can also be used to provide circulation to the tank, so often more circulation is better. With people often aiming to turn their tank volume over between 10 and 100 times an hour. 4 - Noise. My pump is noisey. Its in a sound-controlled room in the garage so I don't care. But if it was in my lounge or bedroom it would be very distracting. Other things come into consideration to - price, internal vs. external, power consumption etc. Good luck Pie Quote Link to comment Share on other sites More sharing options...
HelifaxNZ Posted September 7, 2005 Author Report Share Posted September 7, 2005 Thanks Pie. Good explaination. All things to consider for sure. I'm still wading through the link about your new tank setup. Very impressive. Moving it through your window reminds me of when we had to move a computer mainframe to a new location and we had to pull out a window on the 6th floor of the building and get a crane in to move it out! Cheers Quote Link to comment Share on other sites More sharing options...
chimera Posted September 8, 2005 Report Share Posted September 8, 2005 Depends, but the general rule is as much as possible. Not quite sure if I agree entirely - alot is good but too much could be detrimental. It depends on your filtration equipment. I think 5 - 10 times turnover per hour as a guesstimate for your return pump. You want time for your filtration (mechanical, biological) to do it's thing. For more flow, have a separate system (closed loop, streams etc) in the main tank. Don't forget that the graphs most pump manufacturers provide are based on the output pipe being the same size as the outlet of the pump itself. Never restrict or enlarge the piping from this. Ie: if it's 1" hole in the pump outlet, make sure it's 1" plumbing. Not only will you effect performance you will reduce the lifespan of the pump if you deviate from this. It also assumes water into the pump is not restricted either, go at least the same, slightly larger is better, for the pipe into the pump (for external). General consensus on this forum is Iwaki, Eheim, Laguna are good pumps for the job. Quote Link to comment Share on other sites More sharing options...
Pies Posted September 8, 2005 Report Share Posted September 8, 2005 Not quite sure if I agree entirely - alot is good but too much could be detrimental. Hence the reason I said as a'general rule'. Whos using mechanical and biological filteration in their sumps? Certainly not me. Don't forget that the graphs most pump manufacturers provide are based on the output pipe being the same size as the outlet of the pump itself. Never restrict or enlarge the piping from this. Ie: if it's 1" hole in the pump outlet, make sure it's 1" plumbing. Not only will you effect performance you will reduce the lifespan of the pump if you deviate from this. It also assumes water into the pump is not restricted either, go at least the same, slightly larger is better, for the pipe into the pump (for external). ??? I have never seen anything from IWAKI or anyone else other than Dolphin (different style of pump) saying 'NEVER enlarge or restrict' Now havn't we been through this before? The larger the plumbing, the more water will flow. E.g. if you have an IWAKI 100 (like me) with a 25mm output, it will work better with larger plumbing (say 40mm) than it will with 25mm plumbing. We found lots of calculators on the net that showed the formulas for this, so not sure where Chimera is going with this. Pie Quote Link to comment Share on other sites More sharing options...
Ira Posted September 8, 2005 Report Share Posted September 8, 2005 A lot of it is personal preference too. I have a 6000 LPH return pump which at the head it's working at should be about 4500-5000lph so something like 15X turnover. But that's being cut down even more by the spraybar, need to do something about that. Quote Link to comment Share on other sites More sharing options...
chimera Posted September 8, 2005 Report Share Posted September 8, 2005 I have never seen anything from IWAKI or anyone else other than Dolphin (different style of pump) saying 'NEVER enlarge or restrict' It is more important never to restrict piping going in or coming out of the pump. This increases flow velocity causing abrasive wear on the inside of the pipe (hence why the inlet/outlet are that size for a reason). I have read some sites saying to slightly increase pipe size out of the pump to account for friction loss. If you look at most pumps you will find that, for example, their 1" rating is in fact slightly smaller than 1" piping so by using the same 'size' plumbing you are effectively 'slightly' increasing the size anyway. if you actually calculate friction loss using formulas out there you will find friction (in many cases) is so negligible its hardly worth accounting for it. increase outlet pipe size if you need to get a reduction in velocity to the 'recommended' maximum velocity (i'll dig this figure up got it stored somewhere) Quote Link to comment Share on other sites More sharing options...
Pies Posted September 8, 2005 Report Share Posted September 8, 2005 It is more important never to restrict piping going in or coming out of the pump. Well duh. Smaller pipe = less water, larger pipe = more water flow. Not rocket science. Smaller pipe = more head pressure, larger pipe = less head pressure. Pie Quote Link to comment Share on other sites More sharing options...
jetskisteve Posted September 8, 2005 Report Share Posted September 8, 2005 and we all need more head.......pressure 8) Quote Link to comment Share on other sites More sharing options...
chimera Posted September 8, 2005 Report Share Posted September 8, 2005 I have never seen anything from IWAKI or anyone else other than Dolphin (different style of pump) saying 'NEVER enlarge or restrict' Wondered why you said restricted, so explained why. Well duh. Smaller pipe = less water, larger pipe = more water flow. Not rocket science. Smaller pipe = more head pressure, larger pipe = less head pressure. No, it's not rocket science once you know how, but if HelifaxNZ already knew he wouldnt be asking. Regarding outlet pipe size, the pump outlet size is that size for best performance. Flow velocity is optimally around 6 feet per second. The only time you'd want to enlarge outlet plumbing size would be to reduce velocity to this optimal value. With most pumps, you will find matching the pipe size to the pump outlet size will be at this optimal speed already. If you want to work out whats best, download the water pipe calculation sheet from my web site here Alter the nominal pipe diameter in the spreadsheet until you find a velocity around the 5-6ft/sec mark. Also, here's a good article, part 1 and 2 for Aquarium water pumps. http://www.reefkeeping.com/issues/2002-04/rn/index.php http://www.reefkeeping.com/issues/2002-05/rn/feature/index.php Quote Link to comment Share on other sites More sharing options...
Pies Posted September 8, 2005 Report Share Posted September 8, 2005 Flow velocity is optimally around 6 feet per second. The only time you'd want to enlarge outlet plumbing size would be to reduce velocity to this optimal value. With most pumps, you will find matching the pipe size to the pump outlet size will be at this optimal speed already. Chimera - your on the wrong track man. 6feet per second is the optimal flow velocity if being fed by gravity, but we are not talking about gravity, we are talking about a big ass motor pushing water against (and faster) than gravity. Remeber the old experiment from school, all things fall at the same speed 'maximum velocity' (only impacted by friction). Pie Quote Link to comment Share on other sites More sharing options...
chimera Posted September 8, 2005 Report Share Posted September 8, 2005 Nope, sorry dude, download the spreadsheet above. It's the velocity at the pump outlet. Should be around 6ft/sec. Anymore means too much friction in the pipe causing wear. Remember velocity is not the same as flow rate. In fact, if you actually restrict the outlet to be smaller than the pump outlet, it will cost you more in power (smaller pipe = more head pressure = more work for pump = more Watts) Interestingly, with the 100RLT is has a 1" outlet. Optimum according to the spreadsheet is 1.25" piping (I eat my words) Even so, the outlet size should still be taken as a general rule of thumb for outlet pipe size Quote Link to comment Share on other sites More sharing options...
wasp Posted September 8, 2005 Report Share Posted September 8, 2005 Interesting thread! Since we got all these plumbing experts, something I want to know. First, I'll admit plumbing is definately one of my weak points, to tell the truth I don't even know what a closed loop is. But to the question, when I plumbed my frag tanks, the sump is on the floor and I ran a tube from the pump in the sump up to the top tank. But when looking at it with the 25 ml inside diameter pipe, it looked like just the weight of water in the pipe running all the way up would be quite a load on the pump, it occured to me that if I used a narrower pipe, there would be less weight of water pushing down on the pump. Of course this would be traded off by the pump having to push the water through a more narrow pipe. However, there would be different dynamics involved if the water was going down rather than up. So just wondering if there is some formula or something to work out what's best? Also, guess it depends what pressure rating the pump has. Anyway, just wondered if in this situation I may be better to use a narrower pipe? Quote Link to comment Share on other sites More sharing options...
Ira Posted September 8, 2005 Report Share Posted September 8, 2005 You'll still get the same head with the smaller pipe, IE the same back pressure, but you'll get higher frictional head on top of that. Quote Link to comment Share on other sites More sharing options...
misnoma Posted September 8, 2005 Report Share Posted September 8, 2005 You'll still get the same head with the smaller pipe, IE the same back pressure, but you'll get higher frictional head on top of that. I'm sorry, one should not read that whilst drinking :lol: :lol: :lol: :lol: Quote Link to comment Share on other sites More sharing options...
Ira Posted September 8, 2005 Report Share Posted September 8, 2005 Why having trouble with spitting instead of swallowing? Quote Link to comment Share on other sites More sharing options...
Ira Posted September 8, 2005 Report Share Posted September 8, 2005 Oops, double post. Quote Link to comment Share on other sites More sharing options...
chimera Posted September 8, 2005 Report Share Posted September 8, 2005 Anyway, just wondered if in this situation I may be better to use a narrower pipe? No! Again, don't restrict the outlet piping smaller than the pumps outlet. It's actually quite illogical and hard to get your head around it at first - the smaller the pipe the faster the velocity BUT the slower the flow rate! (as Ira says, this causes more back pressure (resistance) on the pump which actually reduces flow) The more resistance on the pump the harder it has to work which can cause wear and tear on the impellor and motor. Also the higher the velocity through the plumbing the more wear on the plumbing itself. It also means higher power consumption (pump has to work harder to pump under the higher pressure) So, match your outlet plumbing to the pump outlet and you will find you will get much more flow (at a slower velocity) You should notice the water level in your main tank rise if you do this (and it's kinda like getting free 'extra' water movement ). Don't forget when working out static head its the height of the water level in the sump to the height of the water level in the main tank (regardless of where the pump sits in the sump - because the water above where the tank sits provides pressure to the inlet of the pump cancelling out the difference) Quote Link to comment Share on other sites More sharing options...
Ira Posted September 8, 2005 Report Share Posted September 8, 2005 I don't think wear and tear on the plumbing is a particularly big concern. Has anyone ever had their plumbing wear out? Patches worn throw the bends? Quote Link to comment Share on other sites More sharing options...
chimera Posted September 8, 2005 Report Share Posted September 8, 2005 I don't think wear and tear on the plumbing is a particularly big concern At higher velocities it can cause 'knocking' in the water lines (ever hear that when you turn a tap on and off?) Apparently it can cause more wear than you think! Oh, and some more terminology for those interested, dynamic head = static head + accounting loss for bends, valves + friction loss due to piping etc. Dynamic head is the real value you work on for calculating head loss and flow rate at the output. Most just take static head and dont account for friction etc as it's quite negligible (unless you have heaps of bends etc) Quote Link to comment Share on other sites More sharing options...
Ira Posted September 8, 2005 Report Share Posted September 8, 2005 How many people have taps on their tanks that will frequently be turned on and off? Not many, maybe a few ball valves that will be tweaked occasionally, but other than that they're mostly not used unless removing a pump or similar when you'd usually turn it off beforehand. Quote Link to comment Share on other sites More sharing options...
chimera Posted September 8, 2005 Report Share Posted September 8, 2005 :roll: Quote Link to comment Share on other sites More sharing options...
Pies Posted September 9, 2005 Report Share Posted September 9, 2005 Hahahahaha wear and tear on plumbing. Hahahaha elbows wearing thin. Hahahahahaaha how silly. Pie Quote Link to comment Share on other sites More sharing options...
Pies Posted September 9, 2005 Report Share Posted September 9, 2005 Plumbing advice brought to you by the guy who produced this: Lots of elbows in there, hope they don't wear out too quick! Pie Quote Link to comment Share on other sites More sharing options...
chimera Posted September 9, 2005 Report Share Posted September 9, 2005 Lots of elbows in there, hope they don't wear out too quick! No because velocity is right. Do some research you might learn a thing or two. Quote Link to comment Share on other sites More sharing options...
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