Disappointment w/ Closed Loop System

euphoria

euphoria

Active Member
Hey guys,
I finished all the plumbing for my CL system and I'm kinda not too happy about it. I have two 1" pipes meeting a T and then flowing into the pump. The returns are four 1" pipes going into the tank. The overall pressure of the returns is not what I was hoping for.
Do you think if instead of four 1" returns I had smaller diameter (maybe 3/4") returns, I'd have a lot better output pressure, or it wouldn't matter much? I don't even know exactly how much water flow per hour I"m getting out of it, but I don't even want to measure it, cuz it may be disappointing.
Is there anything of a quick fix on this?
 
squidd

squidd

Active Member
Originally Posted by KDFrosty
Going with a smaller diameter return PVC will surely raise your flow rate.
No, it will raise "pressure" and it may "feel" like your getting more flow...(push's harder)...
But you will lower the overall flow or turnover from the system...
 
euphoria

euphoria

Active Member
It's a Little Giant pump, I forgot the GPH rating cuz I threw the box away and the pump doesn't specify it.
SQUIDD - For me most important thing is water turnover and not high pressure jets flowing out of the closed loop system. Would I get the same flow rate if I have smaller diameter pipes w/ high pressure vs. large diameter pipes w/ low pressure? I took fluid dynamics in college but don't remember the relationship
 
turningtim

turningtim

Active Member
Squidd, Isn't flow of the water (Turnover) what you're looking for rather than pressure? Or is there a delicate line between both? Through your posts and other "calculators" I'm seeing a large increase in flow from a 1" return and a 1.25" on my Dolphin 800. I'm setting up a new 55 reef and want to get 20x+. Half from return and half from CL.
Thanks for your past posts! I've learned so much!
Tim
 
mitzel

mitzel

Active Member
Your pump will only flow so much water . The smaller the returns the more presure they will have ,BUT this causes back presure and will actually lower your over all flow rate. GPH is the same weather it comes out as a trickle or as a high presure stream. its just that it seams to be more flow when it is at high presure.
Don't know if that helps
Flow vs presure
makes my head hurt.
 
euphoria

euphoria

Active Member
Well I did a comparison on some online calculator for water flow and going from 1" return to 0.75" return you end up losing (on that particular pump and setup) about 300GPH of water flow. If I had known this earlier, I'd go w/ 1" returns on my returns instead of 0.75" (this is referring to my wet/dry system, not the CL system).
As far as overall loss the GPH went from 2400 gph (for Mag 2400 pump) to 900 gph. That's a ridiculous drop. Is this possible or did I plug something wrong into the calculator?
 
jasenhicks

jasenhicks

Member
Each bend/T fitting etc will add about 1ft of head to your pump, plus the rating of the pump is for one outlet, not 4. Therefore you must apply fluid flow theory to it and realize that you are adding essentially say 4 feet of head to your pump if the 4 branches were 1ft each, and an additional 1ft for each T or 90 degree bend --> this means that you may only be 5 ft from the pump to the return, the pump thinks its say 14ft. Look at the pump curve on the box - say 14ft and see what it says the flow is, it wont be 2400GPH. Look at how much pump head is for 2400gph and its likely 1-3ft.
 
dogstar

dogstar

Active Member
Hi, again
If the pipeing for the returns on your CL going TO the tank is all one inch then your reducing the gph and speed to only 1/4 of the total outflow and speed of the pump at each of the four returns. You can thread 1 x 3/4 in. reducers into the bulkheads and this will force the water thru a little harder/speed with out loosing any total gph thru the TANK. If thats still not hard enough then reduce them again with 3/4 x 1/2 reducers. You may loose some total flow/gph but I dont think it will be much.
If you have over the top pipeing then the same princbles apply, just reduce the 1 in down to 3/4 or 1/2 just befor or after the U bend. Leave the pipeing going back to the pump all 1 in. like it is now in eather case.
 
euphoria

euphoria

Active Member
I am mostly interested in having high water turnover and don't care about blasting pressure from the pipes. When I have all the returns (4 of them) open, the output pressures are not high. They are gently pushing water out of the nozzles. Since I have 4 returns, I may just go ahead and half close two of them, so that more pressure comes out of the other two. Two of my returns are placed at the top part of the tank's back, so that they'll cause surface agitation. The other two returns are placed so that they are branching out of the bottom of the tank. I am more interested in the latter one, cuz I don't need crazy surface agitation and prefer to redirect the pressure to the lower part of the tank. So I may just go ahead and either totally shut down the two top pipes or just close them half way.
By the way, this Little Giant pump is placed outside of my house behind the living room wall, but there's still considerable noise from it. Is there any tricks I can do to lower the noise? The pump is mounted down really tightly and there's great deal of insulation in the wall behind which the pump is sitting.
 
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