Pump Question

[daveb]

Right now I have a GENX 4 that has a 1" inlet, and a 1/2" outlet, so when I did my plumbing I did 1/2" PVC to the Display tank from my sump return. I want to upgrade the pump to a pump that has a 1" INTAKE, and a 1" Outlet. What happens if I leave my 1/2' PVC in place and have the 1" outlet reduce to the 1/2" PVC?? Will my flowrate GPH stay the same but with more pressure at the outlets, or will the flowrate drop. And can it hurt the pump?
Thanks, Dave

 

[scooter8416]

Your pressure would increase at the end of the pipe (just like putting ur finger over the garden hose) because of the bigger pump pushing more water through and your pump should be fine, it just won't be pumping at this rated gph
bigger pipe = more flow, low pressure
smaller pipe = less flow, high pressure
hth

 

[daveb]

I figured.. now, how can you compute how much less flow there would be, by cutting reducing the outlet from 1 inch to 1/2 inch.. I would not imagine it would cut it in half.
Dave

 

[squidd]

No it might be as much as 2/3rds...depending on the pump....
Some, that are not pressure rated "fall off" the flow curve real quick when you restrict them down...others hold up much better..
Post your new pump, ..verticle "head" and how many elbows to get into tank...and I should be able to tell you what your old pump was doing with 1/2", your new pump will do with 1/2" and 1" and what your optimal line size should be...

 

[daveb]

Right now, I have a Little Giant 4MD-SC, it has a 1" intake, and a 1/2" outlet...
I am pretty sure that I figured correctly that I have a pressure head of 14 feet. Vertical from the sump is 5 feet. Horizontal from the pump is 6 feet. There are 2 90 degree elbows, and then two tees, and two 90 degree elbows to each of the four outlets in the display tank.
I have a 1 1/2 inch bulkhead drilled in the sump. So I can accomodate a 1 1/2 inch intake pump. From the research I have done today, my thinking is that if I get an IWAKI MD70RLT I should be able to get between 800 and 900 GPH out of it with my current setup...
Does that seem about right to you?
Thanks, Dave

 

[daveb]

Little Giant pumps, and see that the TE 5 MD-SC model pump is the same plumbing inlet and outlets as the 4 MD-SC pump I am using now. This pump would not require any plumbing change at all, and would get almost about 900 GPH at a head pressure of 14'...
This might be the best way to go don't you think?
The reason I had the 4 MD-SC to begin with, is that I got the pump used, only two months old for $100.00, and it is actually not doing too bad a job. I just want more flow...
I am thinking that I can use this old pump for a closed loop and Oceanmotions 4 way, if I change to the TE 5 MD-SC for my sump return pump... that would give me 10X turn over thru the sump, and then another 700 GPH thru the 4way Oceanmotion...
Does this seem reasonable?
Thanks, Dave
Dave

 

[squidd]

my thinking is that if I get an IWAKI MD70RLT I should be able to get between 800 and 900 GPH out of it with my current setup...
Probably closer to 750...
And your MD-4SC is probably (currently) giving you 470-480...
... and see that the TE 5 MD-SC model pump is the same plumbing inlet and outlets as the 4 MD-SC pump I am using now. This pump would not require any plumbing change at all, and would get almost about 900 GPH at a head pressure of 14'...
:nope: Run that pump and downsize to 1/2" outlets and the bottom drops out...More like 28' head (relatve pressure) and only 800 gph
For that kind of flow the the Iwaki will do it for less amp draw...
Then, if you really can't replumb the multiple outlets, (highly reccomended for better "overall flow" and effeciency from "any" pump) your "second best" bet would be to plumb the feed line from the pump in 1" ..as high as you can go (to the first "set" of splits/"T"s...
Then the Iwaki would give you 1000+ gph...through your current outlets...If you bump every thing to 1" you'll get 1274 ...
The TE-5.5 MDQ-SC really shouldn't be run on anything "less" than 1" and then your looking at 1750 gph...

 

[daveb]

model TE 5 MD-SC , and that pump has a 1/2" discharge but is rated at a higher PSI and will get 858 GPH at 15" head pressure. I see that the TE 5.5 MDQ-SC has a 1' discharge, and puts me in the same boat as the IWAKI, but not the TE 5 MD-SC.
It is not so much that I can't change my return plumbing to 1", I can do it. But I custom built my canopy when I added my Metal Halide lights, and drilled the canopy and hard plumbed it with 1/2" PVC, and really don't want to have to remove the canopy, redrill and replumb, if I can accomplish the same thing just by upgrading to the TE 5 MD-SC pump that has the same 1/2" discharge but a higher PSI rating and consequently more flow at the same head pressure.
So, what is the main advantage to me replumbing for 1" ? If the TE 5 MD-SC has a 1/2" discharge, and is rated at 858 GPH at 15" head, will the flow be better with a 1" discharge pump that is rated for the same flow? I am not sure I am clear on this. I guess what I am asking is, is 850 GPH thru 1" plumbing any better, and why, than 850 GPH thru 1/2" plumbing.
I see the advantage to replumbing at 1" for a pump that would give me over 1000 GPH, but if I can keep the plumbing at 1/2" with the TE 5 MD-SC at 858 at 15' head, and double my flow from the sump return to 850 GPH, and then add a closed loop using the 4 MD-SC, which I can mount higher at the back of the canopy, and get another 700 GPH thru the closed loop I am not sure I understand any advantage. So if there is any real advantage that I am missing, other than possibly using more electricity to run the higher pressure rated pump, I would appreciate the explanation of the advantage that I am missing...
I also just reread your answer, and think I understand something else. You are saying, if I plumb from the 1" discharge of the pump up to the first Tee, and it doesn't get reduced to 1/2" until the first tee, which happens to be above the waterline of the main tank, that in effect reduces head pressure??? Am I understanding that correctly? I was always under the impression that it didn't matter where the reduction was made and that the reduction would have the same effect on flow... but I can see how it makes sense that if all of the vertical head pressure was plumbed at 1" up to the first tee, the reduction would have less effect, since the pump would be pumping against the vertical head pressure at 1" and not reduced until after the vertical head pressure was overcome.??? Am I getting this at all?? LOL
Thanks, so much...
Dave

 

[squidd]

I guess what I am asking is, is 850 GPH thru 1" plumbing any better, and why, than 850 GPH thru 1/2" plumbing.
It "seems" to be... at least IMO/IME and the current trend toward wide flow/Massive movement, compared to high "pressure" directed movement...
Over"simplified" picture below shows a "narrow" band of disturbance on the High pressure "small" outlet and resultant "dead zones"
And then a wider outlet of same flow "pulling" more water with it from a closer range...more "overall" water movement from the same gph flow...even if/especialy if it comes out at lower pressure...less dead area...more "disturbed" area...
So if there is any real advantage that I am missing, other than possibly using more electricity to run the higher pressure rated pump,
Over the "long run" that can be a significant advantage..(in addition to flow charicteristics)
if I plumb from the 1" discharge of the pump up to the first Tee, and it doesn't get reduced to 1/2" until the first tee, which happens to be above the waterline of the main tank, that in effect reduces head pressure???
Yes and no...It's not so much a reduction in head pressure from reducing "vertical" height as it you are reducing "relative" head pressure (restriction) by staying larger and then "multiplying" outlets and maintaining some resemblence of a larger diameter pipe...
Am I understanding that correctly? I was always under the impression that it didn't matter where the reduction was made and that the reduction would have the same effect on flow
"IF" a single line started at say 1" and then was reduced to 1/2" the entire length would be counted as the smaller diameter...1/2"...
But if you start at 1" and then at a certain point "split" to 4... 1/2" outlets you stlll maintain the "relative" ID of a larger line...
Now you still have to factor in losses from the 90* turns you just made the water make...(it doesn't like to do that)..in those "T"s, but for the most part you've maintained a larger ID by going to "multiple outlets" at that transition point...
>Man I could just imagine their little heads "spinning" if I put this in that "Plumbing 101" thread<...

 

[daveb]

You have been a tremendous help! And I understand completely, and am convinced that my best course of action is going to be to bite the bullet and replumb to 1" and go with the IWAKI with a 1" discharge....
The fluid dynamics of larger low pressure flow make sense to me also. And since my sump is 50 gallons, it sure won't hurt any to have 1000 to 1100 GPH going thru it....
Just as a side note... I live in St. George Utah, where if you payed attention to the little blurbs in the news, we just had a severe early melt of the snow pack below 7000 feet in our surrounding mountains, causing a major flood along a river here. We had a power outage because of this, and I was please to find that my sump design handled it perfectly... the sump handled all of the siphon back without overflowing, and when the power came back on, the system came back up as if nothing had happened. It was a very nerve destroying hour, but in the end, the real life test of the design has made me sleep better now with confidence I didn't make any mistakes in my calculations... LMAO
The one thing it did make me realize is that I do need to get a generator that will power a couple of the main pumps in my system during a power outage. Even though this was a short one, I was a mess wondering how long it would be and how long my tank would be ok without any flow. So tomorrow I start a new DIY project that I had read online somewhere about a self starting generator system to power this mess during a power outage. I just love this hobby, as I can clearly see there is no end in sight of things to do.... LMAO
I might as well put a nice third coat of finish on the canopy too while I have it off !!! LMAO
Thanks,
Dave

 

[squidd]

And since my sump is 50 gallons, it sure won't hurt any to have 1000 to 1100 GPH going thru it....
As long as your "Overflow(s)" can handle it...!!
Must be nice to be retired...:yes:
Of course, that would entail having a "Real" job first....:scared:
:hilarious