new magdrive pump question.

[dolciflyer]

i just purchased a magdrive 1800 gph pump. great piece of equipment, much more quiet.
i've got about 5 feet of head on the pump. seems with my crude measurement, i only get about 600gph out of it, and my tank is 180true.
the inlet and outlet fittings are both 3/4", the plumbing i used is all 1". it suggests 1 1/2", will that make the difference of 800-1000gph??? should i return it for the 2400gph?
what i've got certainly doesn't pump with the velocity of my old, albeit louder, pump. i believe the old one is some model of iwaki, and it's flow rate is around 1500gph - ish.

 

[marinerock]

HEY DOLCI....
GREAT PUMP...I DONT THINK THAT WOULD CUT DOWN THE
FLOW RATE THAT MUCH....THINGS THAT DO CUT DOWN THE
FLOW RATE ARE TOO MANY TURNS IN THE PLUMBING, A
CHECK VALVE WILL CUT IT DOWN A VERY LITTLE BIT.
YOU DONT NEED THE 2400, HOW MANY TURNS(I.E. ELBOWS)
ARE YOU USING FROM THE RETURN PUMP TO THE BULKHEAD?
YOU ALSO SAID THAT IT SUGGESTED 1 1/2" PLUMBING...
FOR WHAT ?
REGARDS...
MARINEROCK

 

[jumpfrog]

A Mag18 should get about 1100-1200gph at 5' head according to their own charts. I would think the plumbing diameter would have some impact on the gravity (flow) side but not that much on the forced (pump) side. Do you have lots of turns as MARINEROCK hinted at?

 

[dburr]

Yes how many turns and the dia. can effect it.
I use the 950 w/ 9/10' head and have 400 GPH. I used 1/2' pipe instead of 3/4' but with my head it dosen't matter. I also used 45 degree turns (4) instead of 90 which also helps.
hth

 

[splash1914]

this weekend I am swaping my iwaki pump for a mag 18.... I will let you know how mine does..... I can tell how much flow by looking at my prefilter....

 

[scotts]

Since you used a 3/4" outlet fitting your flow rate will be based on the 3/4" fitting size, not the 1" pipe size. Also there is a large difference between the area of a 1" pipe and a 1 1/2" pipe. I will let you do the math but it is based on the area of the pipe which is the radius squared mutlipiled by 3.14156. remeberber that is the radius, not the diameter. Have to go. please post if you need more help.
Scott

 

[splash1914]

I hooked up my mag 18 and its not pushing nearly what I thought it would.... the charts say it should push more than my iwaki and its not even close..... I used all the same plumbing as the iwaki.......I knew I should I of bought the mag 24!

 

[dolciflyer]

splash, don't buy the 24!! the instructions that came with the 1800 say not to use less than 1 1/2'' plumbing for the output. this is very true, even tho the output fitting on the pump is 3/4'', the 1.5'' plumbing to the bulkead made a HUGE difference. i used only 1 T, and then 1.5'' flexible pvc tubing. so there are no turns except the T, and the curve of the tubing. the flow is now greater than the old iwaki. i'm very impressed. just not impressed at how the threaded intake on the pump cracked after hooking it up the second time. no problems tho. just submerged it, and all is well.

 

[splash1914]

do you have a pic of yours? I read that too and thought why is the output 3/4" then! the problem I have is I have a 3/4" return stand pipe in my prefilter area that is about 20"H.. ... so your saying if I go from the mag which is 3/4" to 1.5" (this will be about 2.5 worth) then to my 3/4" stand pipe it will push alot more?

 

[dolciflyer]

splash, definately! i'm a plumbing guru after this project. i just found a 3/4'' female to 1.5'' connector to attach to the pump, and made my own connections to the standpipe, using a 1.5'' hose barb, and bringing that down to the 3/4'' threaded male fitting to screw into the bulkhead. it makes all the difference in the world, especially if you can use the pvc tubing instead of the pvc pipe with elbows. it sounds like i have the same sort of setup that you do. i have two returns, one in each corner, so i had to use a T. i'll try to get a a pic for you.

 

[splash1914]

thanks, here are some of my filtration pics... that way you sort of see what I have....
filtration
I appreciate you help!! Now I have to empty the sump out for the third time!!!!

 

[rockface]

splash, what are you using for lights? looks great.

 

[marinerock]

HEY DOLCI.....
HEY SPLASH...READ THIS BEFORE YOU DO ANYTHING WITH THE PUMP....
DOLCI...
YOU SAID YOUR THREADS CRACKED ON YOUR PUMP ON THE
INTAKE END....I POSTED THIS QUITE A FEW TIMES ALREADY...
BE VERY CAREFUL AND LINE UP THE FITTING FOR THE
RETURN END OF THE PUMP AND USE TEFLON TAPE BEFORE
YOU EVEN ATTEMPT TO SCREW IT ON.....IT WILL CRACK,
AS THEY ARE NOT THE STRONGEST THREADS....
SO IF YOU DECIDE THAT YOU HAVE TO MOVE THE PUMP OR
WHATEVER....LINE IT UP FIRST AND DO NOT OVERTIGHTEN...
ONLY HAND TIGHTEN.....
WHEN REMOVING THE RETURN FITTING....DO IT VERY SLOWLY...
WHEN REPLACING THE FITTING....REMOVE ALL THE OLD TEFLON
TAPE AND INSTALL NEW TEFLON TAPE IN THE DIRECTION OF THE
THREADS ONLY....ONLY OVERLAP A TINY BIT AND ONLY ONE LAYER.
REGARDS...
MARINEROCK

 

[dolciflyer]

thanks marinerock. i've learned all of what you said from prior experiences. the intake for the pump, with the inside threads, is what cracked, i only hand tightened it, definately used teflon tape. it's funny that it cracked after quite a few hours of being connected. it's brand new, so i may consider using the warrnanty, but i rather like using it submerged as it reduces extra noise.

 

[marinerock]

HEY DOLCI....
I USE MINE SUBMERGED ALSO... VERY QUIET...GREAT PUMP...
JUST HAVE TO BE CAREFUL WITH THE THREADS...
I NEVER USED IT OUTSIDE THE SUMP...IS IT MUCH MORE
NOISIER THAN INSIDE THE SUMP ?
REGARDS...
MARINEROCK

 

[dolciflyer]

the difference is nominal, but noticeable. still WAY quieter than the old iwaki i have. glad i made the switch.

 

[splash1914]

rockface, thank you, I use home depot fixtures with two 4' blue atinics and two 4' full spectrum
marinerock, thank you for the advice
dolciflyer: which iwaki pump were you using?

 

[dolciflyer]

i have no idea which iwaki pump it is, it was given to me with the setup, and i have no paperwork on it. pretty decent workhorse tho. pumps at least 17-1800 gph 0' head.