flow problems

[spikehs]

I have my plumbing all hooked up and the tank full of water, but I am getting virtually no flow from the outlets to the tank, if I put my hand over it I can barely feel the flow at all, the pump is a mag 250, so I figured I'd be able to feel/see the flow a bit. I was thinking I might have to many 90deg bends, but I really can't see them reducing the flow that much. Anyways here is a picture of the plumbing:

the long tube comming over the back is the intake, then its plumbed into the 2 returns which then split into 4 (see second pic)



in the 2nd pic you can see i popped off the tube to see what the flow was like there, I coud still barely feel it.


might the pump be faulty? The only other thing I can think of is that the intake is somehow restricting the flow to much, otherwise I am kinda stumped. Any help would be appreciated. thanks.

[Aquattro]

A MAG 250 going thru that many 90's into 4 outlets will give you pretty much what you've got. Maybe a MAG 7 would be a bit better....

[kari]

Hose to barb connections are good at creating flow restrictions aswell. PVC flex hose glued into slip fittings might help some. Limit the use of 90's as much as you can (as already noted.)
Also, maybe a second pump might be an alternative.

I figure if something doesn't work, throw more money and electricity at it.

[mark]

There's a flow calculator on reef central. If you play around adding and subtraction elbows etc., you'll get an idea of how much loss they add.


http://www.reefcentral.com/calc/hlc2.php

[spikehs]

thanks for all the advice, I guess I am going to have to redo the plumbing, after all that cursing and swearing too! Maybe I'll go with some loc line, does it seal well enough to use it for external plumbing? does anyone know where to get some of this stuff? thanks (again)

[Aquattro]

Keep in mind you're using a pump that is only slightly more powerful than a Maxijet 900 powerhead. And I can't imagine splitting the output of a powerhead into four!! That wouldn't be enough flow for a 15g tank, IMO.

[Richer]

Agreed, a mag250 isn't all that powerful... imho you would be better off dedicating that pump to a single outlet... or if you want, something that switches your pump between outlets (like a SCWD, etc.)

-Richer

[spikehs]

yah i didn't really take all the bends into account, i was thinking I would get 250gph through the whole thing (stupid me). I was also going to hook it up to a scwd but its currently on my old tank that I am taking down... If i dont change the plumbing (which I probably will now) how big a pump do you figure I'll need to get about 10x or more out of it?

[JohnM99]

What is the inside diameter of your pipe? It looks fairly small.
There is an enormous difference in flow with only a small increase in radius - exponential - also, as said before, a Mag 2 isn't very powerful.

Unions, els, valves - all fittings - reduce flow. It looks like you have a lot of connections - also, all non-glued connections introduce the possibility of air leaking in giving you microbubbles. You might find that if you hook this up to a more powerful pump, you might get a lot of microbubbles.

Gluiing PVC is not nearly as bad as it sounds. If you cut all your pieces first, it doesn't take long. If you are as messy as me, consider getting clear primer instead of the usual purple stain. Use the least number of 90s possible (a gentle curve has less pressure effect than a 90) and use a decent size pipe.

RC has a lot of resources for novice plumbers like me, which were really helpful.

Good luck.
John

[spikehs]

Originally Posted by JohnM99

What is the inside diameter of your pipe? It looks fairly small.

its 1/2" id, I would have gone bigger but that was the diameter of the outlet on the mag...back to the drawing board for the plumbing! oh well, live and learn i guess.