pump ???

[madean]

I recently purchased mag drive 9.5 from a lfs. My question is about flow loss with my tank set up. The pump will sit in a sump and pump water vertically roughly 26" to a bulk head (which is the bottom of the tank) enter the tank split into two return lines (via 120 degree wye fitting) then travel diagonally up out of the water then horizantally about 8", then back down into the water about an inch. Might sound crazy but I want to drill anti syphon holes to prevent excessive water return if the power fails. My dilemma starts because the tank was drilled for a 1" bulkhead, at the bottom of the tank, and the outlet on the pump is 3/4". Will i loose a considerable amount of flow loss by plumbing everything to 1" (ie 3/4" to 1" bushing and then 1" piping and fittings all the way out to the outlet)? Would it be better to just bottle neck the bulk head (ie make everything 3/4" before and after the bulkhead)? Or would it be better to increase to 1" at the pump to the bulkhead and after the bulkhead reduce down to 3/4". Any information will be greatly appreciated.

[madean]

^^^

[sjm817]

For flow, bigger is always better. Using 1" would be better than 3/4". 1.5" would be better than 1". Even with the 3/4" bulkhead

[jefathome]

I disagree with SJM to an extent... If it is 3/4in on the pump, then using 1in at the "outlet" will not increase the flow at all.

[sirreal63]

Mag recommends a minimum of 1-1/2" inner diameter for maximum, and rated flow. Scott is right, and this is a common misconception. You hook up a Mag 9.5 with 3/4" tubing and you will not get any where near 950 gph.

http://155.212.86.141/instructionsheets/ZG100.PDF

[madean]

sirreal63- thanks for pointing that out. I could have sworn that I read all of the directions but I missed that capatilized sentence under the flow chart that says 1 1/2" inside diameter is the minimum hose size that should be used for maximum flow. Some how I missed that. I even emailed danner this question and their response was to not bottle neck the pump because it will create back pressure, which I argree with. So using pipe that is bigger than your bulkhead is not a good idea and can decrease the life of the pump. So for my application I think I will increase to 1" throughout and go that route. Some good info for people. Thank you all for your input.

[madean]

sorry typo, using pipe that is smaller than the bulkhead after the bulkhead is a bad idea.

[sjm817]

As above, it is an unfortunate misperception that increasing pipe size does not increase flow. It does and in many cases such as with a Mag9, dramatically. There are many people running high flow pumps with low flow plumbing getting only a fraction of the flow that they think the are.

[reefsurfing]

I have 3/4" flexi tube running to my 1.5" return line. The 3/4 is about 18inches and the 1.5" is about 2ft long, should "I loose the 3/4" flex all together?

[sjm817]

If you want some more flow, yes you can try that. If you are happy with the flow you have, no need to change anything.

[madean]

sjm817 due you suggest that the pipe diameter be immediately increased to an 1 1/2" from the pumps 3/4" outlet? Can you explain this better as to why the flow is increased? I have a basic understanding that there is more friction loss in smaller diameter pipe compared to larger diameter pipe. Basically the percentage of water that comes into contact is greater with smaller pipes compared. Is this the answer. There has got to be a point where the diameter of the pipe, as it is increased, will hurt the output or flow. Is 1 1/2" just the sweet spot for these pumps?

[madean]

upon further inspection of the danner website every pump bigger than the mag 7 has a recommended inside diameter outlet of 1 1/2". Conversly there is not a recomendation for the smaller pumps. unless I missed that again.

[madean]

Sorry sjm817 I have more questions for you. Lets say i did run a 1 1/2" from the pump all the way up to the bulkheads but I did not want to have a 1 1/2" return line can the return line be tee'd off to lets say 2 or 3 3/4" bulkheads with out significant flow loss. What I mean to better clarify, is the total flow from 2 or 3 3/4" lines which tee's off from a 1 1/2" line be somewhat equal to just having 1 1 1/2" return line. I hope this makes sense. I'm trying to limit the amount of water returning to my sump in case a power failure. For me and my set up, for every inch of water returning to the sump equals roughly 11 gal of water displacement. My tank is big, but very shallow. So I dont want a large quantity of water flow in one area either. I guess I am trying to guage whether to have 1- 1 1/2" return line and just compensate by adding more filter space in the sump or having multiple 3/4" return lines space close together and using loc lin to direct flow to different areas. Any info would be greatly appreciated sjm.

[madean]

????

[sjm817]

You dont HAVE to run 1.5" all the way. A single 1.5" return in the display is not very attractive looking either. Again, if you want to get the maximum flow from the pump, use the really big plumbing. If you could live with less, you dont have to go that big. Splitting the outputs to multiple 3/4" outlets at the display is a good idea and is what most people do. Keep them just below the surface to minimize drain back to the sump.