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)

http://www.missolutions.ca/~sean/fish/f1.jpg

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.
http://www.missolutions.ca/~sean/fish/f2.jpg

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]

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! :rolleyes: oh well, live and learn i guess.

[JohnM99]

Yeah, that's your problem. Half inch is very restrictive. The RC calculators don't even include half inch as a choice.

I would suggest redoing it with at least 3/4, using glued PVC. Just because the output on a pump is a certain size doesn't mean you have to use that size - adapt up at the source.

With 3/4 you should get around 150 gph based on a very rough run through the calculator (with guessing). Half inch would be just around the fourth root of that (flow varies as radius to the fourth power I seem to remember) which is about 3.5 gph. ie almost nothing.

Experience is nothing more than a long line of screw ups!!! Have fun.

[Aquattro]

Just curious...what size is this tank?

[spikehs]

Just curious...what size is this tank?
it is 25gal cube (18x18x18) with an 8 gal fuge attached directly on the back.

I guess what my problem is now, is that I had 1inch holes drilled, but the bulk heads are 1/2inch.. does anyone know how much flow you can safely run through a 1/2inch bulkhead?

[Delphinus]

Pipe size doesn't have to be restricted to those on the pump outlet/inlet. You can use bushings to switch to a different size. What I'd do is use at least 3/4" or even 1" ... it does make a big difference.

You could try leaving the 1/2" bulkheads in for now but using 3/4" or 1" on the pipes, and see how it goes. The bulkheads themselves will be a slight restriction, obviously, but it might not be too bad. Failing that you may need to get the holes enlarged, but jump off that bridge only if you have to.

Basically by stepping up the pipe diameter, also going PVC with glued fittings, and maybe stepping up to a Mag7 or a Mag9 even, I'd bet you'd probably get the kind of flow you're looking for. Just my guess though ... always a little bit of trial and error at first when doing these setups.

If I had gotten a nickle for every time I redid my plumbing for every tank, I'd probably have gotten enough to pay for all the extra little PVC bits that I went through!!!!!! :lol:

[Aquattro]

I would just suggest upgrading your pump to a MAG 7 or 9.

[spikehs]

I am looking to push around 15x (or more if possible) the tank volume.....

Well this is my "current" plan (it'll probably change again :rolleyes: ). I am going to plug up one of the holes on the back and put a valve on the other, and use that to drain the tank for wc's.... then I am going to place the pump inside the sump/fuge and use pvc or loc-line to plumb it to the 4 outlets (can't decide between the 2, any opinoins?)... anyone see any problems with this plumbing setup? thanks.

[Richer]

I would plumb with PVC, because its widespread and easy to get. Keep in mind that with mag pumps, its suggested that the user should use a pipe with an id doulbe that of the output of the pump for maximum flow. So if your output is 1/2", using a pipe/tube with an id of 1" would maximum flow. I've heard of several people who've had flow problems with their mag pumps because they didn't use the proper pipe diameter.

If you're going to use the mag as a return pump from your sump, I would personally go with a mag7 or 9.5. Flow can be easily adjusted by adding a ball valve to the output of the pump.

-Richer