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View Full Version : Anyone using eductors on return pumps?


Myka
06-14-2013, 06:18 PM
I'm back to working on my 100-gallon 48x20x24" tank. It was built for me a few years ago, and I honestly can't remember why I got two return holes drilled... http://www.reefcentral.com/forums/images/smilies/lol.gif I have an OM 2-way that's been sitting in a closet for several years and figure maybe I should hook this up to my return pump for more flow options. The return is a Poseidon PS3 with about 660 gph at 5' head pressure not considering plumbing. Obviously, this won't be very significant because the return pump isn't very big, and I don't want more flow through the sump. Seeing as this pump is pressure rated, I had the sudden thought today that maybe I should add a couple eductors to the returns. http://www.reefcentral.com/forums/images/smilies/idea.gif

This should make it so that there is about 1800 gph flowing out the eductors and switching back and forth from the right return to the left via the OM without increasing flow through the sump. I've never used eductors, so this is uncharted territory for me. Has anyone tried something similar to this? Is it worth the effort and complication of plumbing or should I just toss the towel and plug that extra return hole? I'm not willing to go through the headache of all this extra plumbing if there would be no benefit. I'm a bit worried the powerful powerheads (two 6105 and one 6055) I have might just wash away that 1800 gph and make it a moot point. I would not be impressed. :lol:

lastlight
06-14-2013, 06:27 PM
PS3 isn't really a pressure rated pump is it? from what i read the eductors won't perform the same with flow pumps.

Skimmer King
06-14-2013, 06:27 PM
Mindy, I think IMO that people using longer tanks use them. But for a 48 long I dont think you would need them. why not just down grade your plumbing return line. if its 1" have it coming out as 1/2" just a thought and that pump isnt really a Pressure rated pump like a iwaki

Reef Pilot
06-14-2013, 06:32 PM
On one of my tanks I Y tee'd the loc-line return, so that I have both surface flow and deeper flow. The deeper outlet has an eductor end and seems to work well with lots of flow. Having said that, I have no way of measuring it, so of course can't say for sure. But it does seem to accelerate the flow there, so I think it does work. Oh,... and the return pump is 900 gph, and the loc line size is 3/4".

Myka
06-14-2013, 06:52 PM
Actually, the Poseidon line operates up to 50 PSI. The PS3 max head is 26'. The Poseidon PS3 is comparable to the Iwaki 55RLT although this Iwaki is also 26' max head and 1100 gph at 0' head it is only rated up to 17 PSI. Plus the Iwaki 55RLT uses 190 watts where the Poseidon uses 140 watts.

If I don't use the eductors and the OM there is no point in reducing the return opening because it wouldn't increase the flow enough to be usable. That's what I'm worried about with the eductors...will it be enough to be noticeable? Will the eductors increase the return flow enough that the flow will hit the bottom of the tank and thus be useable to help keep detritus suspended at the rear of the tank? I don't normally look at the return as a source of usable flow, to me it's job is to operate the sump and bring flow to the skimmer. I'm simply trying to justify using the OM and the second return hole in the tank. :D

Skimmer King
06-14-2013, 06:59 PM
Mindy the eductors are like what I have stated . If you have a 1" return line and you go to a 1/4" at the end its going to have the same effect as one of those. if you crimb the ends somewhat or use loc line then you can get the same effect. its not going to take much to push flow in a 48" tank.. just sayin or I suspect that you should just close it up and use one opening

Myka
06-14-2013, 07:02 PM
mindy thge eductors are like what i have stated if you have a 1" return line and you go to a 1/4" at the end its going to have the same effect as one of those. if you crimbthe ends somewhat or use loc line then you can get the same effect. its not going to take much to push flow in a 48" tank.. just sayin

That isn't the same effect. Reducing the line increases velocity, not volume. The eductors increase volume. I want to hit the bottom of the tank, not go across the length.

http://www.advancedaquarist.com/2003/9/review

http://aquafinatic.com/images/Aq%20Eductor%20Diagram.jpg

sphelps
06-14-2013, 07:06 PM
I seem to recall eductors needing around 20psi @ 500GPH to be effective so since you may be in the ball park it makes sense to try them out considering they are an inexpensive addition. However I also seem to recall that OM units are not designed to work with eductors so perhaps an email (or phone 1-877-812-4108) to Paul from OM would be a good idea.

Myka
06-14-2013, 07:07 PM
I seem to recall eductors needing around 20psi @ 500GPH to be effective so since you may be in the ball park it makes sense to try them out considering they are an inexpensive addition. However I also seem to recall that OM units are not designed to work with eductors so perhaps an email (or phone 1-877-812-4108) to Paul from OM would be a good idea.

Yes, I have read this mentioned a couple times as well, but can't find any specific information. I'm not sure why it would affect an OM. I will look into it.

EDIT: Just found this...the back pressure from the eductors can put pressure on the drum of the OM and although it doesn't cause damage, it will prevent the drum from turning. There seems to be a way around this... keep posted. :p

http://archive.reefcentral.com/forums/showthread.php?t=578481

Reef Pilot
06-14-2013, 07:15 PM
That isn't the same effect. Reducing the line increases velocity, not volume. The eductors increase volume. I want to hit the bottom of the tank, not go across the length.

If you are just trying to stir up the bottom to suspend detritus, not sure this is the best way. The flow will be concentrated in one spot, which will be very clean, but the detritus will just be moved to somewhere else in your tank.

I also have the Coralife DC 5800's, one on each side of a 6 ft tank. I set them to turbulence mode which varies where the flow meets to blast the bottom and doesn't let detritus build up in one area. I think all the wave maker type pumps, like ecotech and tunze, work that way.

Myka
06-14-2013, 07:29 PM
If you are just trying to stir up the bottom to suspend detritus, not sure this is the best way. The flow will be concentrated in one spot, which will be very clean, but the detritus will just be moved to somewhere else in your tank.

I also have the Coralife DC 5800's, one on each side of a 6 ft tank. I set them to turbulence mode which varies where the flow meets to blast the bottom and doesn't let detritus build up in one area. I think all the wave maker type pumps, like ecotech and tunze, work that way.


Well, I do have the three Tunze pumps on a controller as well. I run the 6055 behind the rocks in my 90 and it works well to keep detritus from settling behind the rocks. I do have one spot in my 90 that I can't seem to get the detritus out, so I just siphon it out. Both the tanks are bare bottom.

Honestly, I'm really just looking to justify the use of the 2-way that's collecting dust. I don't want a closed loop and there is no point in using the 2-way on a 660 gph return line, buuuut if the line has an eductor on it increasing the flow to 1800 gph then perhaps it could be useable. :razz:

Reef Pilot
06-14-2013, 07:33 PM
I do have one spot in my 90 that I can't seem to get the detritus out, so I just siphon it out. Both the tanks are bare bottom.


Well it could work for that, if your Tunze's keep the rest of the tank bottom clean. Give it a try, and see what happens.

Myka
06-14-2013, 07:40 PM
Well it could work for that, if your Tunze's keep the rest of the tank bottom clean. Give it a try, and see what happens.

This plan is for the new tank. The rock will be designed much different...if I manage to have the patience to make it the way I want to.