Plumbing Advice Please

[Pazil]

Here is a picture of the current setup. My tank has just started to cycle. I am not getting a good flow from the DART return pump. I was told this is because I have reduced the 1.5" outlet down to a 3/4" after the true union and then teed off for the 2 3/4" returns. What do you guys suggest I do here to increase the flow in the DT while keeping the same pump. Please keep in mind that I only have 2 3/4" bulkheads drilled in the over flow for the returns and there is very limited space. There is also 2 1.5" bulkheads in the overflow for drains (1 main with a gate valve and 1 emergency). Any ideas would be appriciated.

Cheers

 

[the_blue_tuna_2]

I think you could help yourself out a bunch by running up to the bulkheads in 1.5 then reducing right at the bulkheads.

 

[teesquare]

A restriction is a restriction - no matter where it occurs in the plumbed line.

You will never get more out of a pipe than the maximum flow for the SMALLEST point in the line, - i.e. look up the max flow for the smallest fitting, or restriction in the line. That is it.

It may be simpler to reduce the pump size given the small returns.
Don't want to the the bearer of bad news - just the facts I am afraid..
Good Luck-
T

 

[the_blue_tuna_2]

I am going to have to respectfully disagree with you on that , especially when restrictions are right at the end of the line . You can run the the numbers on the head loss calculator with .75 vs. 1.5 . The 1.5 flows almost 4 times the volume of the .75 . If you were to use that logic no pump would flow at or near its rating unless the outlet were the same size as the return piping and that is almost never the case .

 

[Pazil]

So if I run the 1.5" PVC out of the return pump and then into a tee and continue 2 - 1.5" PVC pipes upto the under side of the overflow then reduce each one down to 3/4" and into the bulkheads and then continue each 3/4" pipe up to the overflow box and intothe 3/4" bulkheads and then into the tank. This should increase flow by approx. how much.

I hope I got that right...

Thx again for your help here

Cheers

 

[the_blue_tuna_2]

I dont know by exactly how much you would increase your flow , but just simple reasoning would say that if you replumb in 1.5 from your valve up to and including that tee you see in the pic , then reduce the 2 ends of the T to .75 , so that each bulkhead had its own .75 inch supply , then you should double the amount of water you are putting into the tank. Teesquare does make a valid point though , with only 2 .75 inch bulkheads , you really may want to consider a smaller pump.

 

[jwilliams860]

I have a dart for my return on a 300 gallon setup and its plumbed with 2" in and 1.5" out until I reach the 1" returns, and I have mine more then half way valved down with a valve on the out, if its open any wider, it drains my sump faster then the 2 1.5 drains can fill it back up, and another rule of thumb, youd rather have slow flow from your sump/refugium to give your skimmer more dwell time, give it time to do its job, instead of pulling water so fast through your sump its not really working as effectively as it could.The Dart also will use less watts if you valve it down also.I dont use my return dart to really push the water around the display tank, I use the closed loop and Vortechs for that.

 

[james3370]

i would run a single 1.5 as far as possible & THEN t it to the bulkheads (still 1.5) & reduce to 3/4 right at the bulkhead

i would also suggest coming out of the union ball valve up to the t-fitting in flexible pvc....gradual turns that can be done w/ the flexible pvc will be exponentially less detrimental to the flow rate than hard plumbing w/ right angles

you can order the flexible pvc from flexpvc.com & while you are at it, might as well order a 1.5" tru-wye to use instead of a t-fitting...should also be less restrictive

http://www.flexpvc.com/cart/agora.cgi?product=PVC-Wyes_TrueWye

that's just my 2-cents

 

[teesquare]

blue tuna:
We did not disagree - or at least it was not that I was correcting you in my post: just pointing out a fact that every plumber knows.
You total flow out of a pipe, is never greater than the maximum flow potential of the smallest diameter in that line. It is just physics.
Use this example:
A gravel cleaner for aquariums ( like a Python or similiar) You have a large barrel on the end, which sucks up the debris, and a much smaller tube going out of the tank.
Don't you think that "size matters"? What do you think happens if you remove the larger barrel...? Nothing. But what would happen if you place a smaller diameter one foot section of tubing anywhere in the line?
You reduce the flow. Pressure or no pressure, the CAPACITY of the pipe, or any restriction in it ( this can include reduced size pipe, tees, elbows, etc.)
Volume, and pressure are relevent and maybe this is something to consider - if you "pinch" or restrict the pipe, you DECREASE flow. I am sure you have done this with a garden hose - right? But - you INCREASE pressure....(Which can be expressed as additional static head in calculating the flow)
In the case of the pumps - All of my Hammerheads are the same size input and out puts, as are my Iwakis.... I don't understand wha you mean in the statement:
If you were to use that logic no pump would flow at or near its rating unless the outlet were the same size as the return piping and that is almost never the case .
Please explain.
Thanks
T

 

[the_blue_tuna_2]

T when I say outlets , I was referring to the end point , such as a bulkhead or a sea swirl . It seems that often I dont type so clearly.

 

[teesquare]

O.K....
If I understand, the end point is analogous to the end of a pipe?

If that be the case, it is a restriction, should it be smaller than the inside diameter of the rest of the plumbing. Make sense so far?
The calculable difference between it occuring at the discharge of the pump -vs- the end of the dischage pluming(bulkhead) is not much. Save for elbows, tees, and vertical height.
But the impact of the down sizing or restriction is the same... reduced flow.
If a house is on fire, the firemen arrive and the fire hose is too short, but they substitute the first section, or middle piece or the very end closest to the house... What is the net result? Reduced flow. You will not get any greater quanity of water from the garden hose, just because there is a fire hose connected to it on the upstream or pump discharge side. You will only get from the fire hose what the garden hose can through-put in volume.
Again - I say this not to argue, but to hopefully help Pazil be able to know what to expect in actual flow.
Just as the old expression goes "a pint cannot hold a quart" the smallest diameter of pipe is what regulates the maximum flow measured in volume of water here. The restriction may increase pressure, given that the increase in pressure does not stall the pump by exceeding the "shut off"- or max. head that the pump is designed for.
A Dart is not a high head pump.... Just something to consider.
Cheers!
T

 

[das75]

Can see it making a difference on a long run where the reduction first occurs as to consider head loss attributed to the pipe run itself.

My case have a basement return pump, probably 20 plus linear feet to the 1" bulkhead on the bottom of the display. Sure I'm getting better flow using 1.5" from the pump up to the bulkhead rather than if I reduced right at the pump to 1" (and did the run completely in 1").

 

[teesquare]

I would be interested in the math you use to measure the difference you see...

You will have a lower friction loss with larger diameter pipe, but that becomes a negated point, because you really have 1" pipe - as far as actual output.
The 1-1/2" pipe does benefit you in that you avoid some pump cavitation because the long run of 1-1/2" acts as a "buffer" of sorts, prior to necking down to 1''.
T

 

[livingstone]

Re: Plumbing Advice Please

<a href=showthread.php?s=&postid=14528145#post14528145 target=_blank>Originally posted</a> by Pazil
...I have reduced the 1.5" outlet down to a 3/4" after the true union...

At least run 1.5" into the tee.

 

[reefscape15]

Agreed with livingstone

 

[Pazil]

I will do just that..... 1.5" to the tee and then down to .75" through the bulkheads and into the tank.... I really wish I could find some PVC Y's here locally instead of having to use t's

Thanks for all your advice

 

[Pazil]

Well I had a chance to redo the return plumbing for the sump and ran the 1.5" all the way up, into a tee, and then reduce to 1" and immediately to .75" into the bulkheads and then into the tank. While I was at it I added a few .75" outlets for future use. I would estimate that this has at least doubled the flow over what I had previously. Here is a pic of the revised setup..... Thanks for all the comments.

Cheers