No More Power Heads!!! Use Eductors!!

ivgonmad · 04-17-2007, 04:45 AM

I made these Eductors out of PVC Parts for under $5, click on the link for instructions, just too much work to post it again...

They can provide all the necessary flow to your tank, eliminating powerheads and closed loops.

CLICK HERE FOR MORE INFO!!

Geoff · 04-17-2007, 11:06 PM

yes eductors are great fun. we had a group project about DIY eductors about a year ago. here is the thread. they are very similar to your design.

right now i have two CLS's with eductors on them. i find them great on long tanks.

G~

ivgonmad · 04-18-2007, 05:27 PM

Quote:

Originally Posted by Geoff

yes eductors are great fun. we had a group project about DIY eductors about a year ago. here is the thread. they are very similar to your design.

right now i have two CLS's with eductors on them. i find them great on long tanks.

G~

Yup, I followed that thread but found some errors in the design so decided to make one that would use a little lees pressure but with a greater effect.

That is why mine is a bit larger, to generate a slower, wider stream and to educt more water with less pressure.

ivgonmad · 04-18-2007, 05:28 PM

Link up top does not work for some reason, try this one:

CLICK HERE!!!!

bosscrab · 04-18-2007, 08:21 PM

Looks pretty awsome! think I will try to hook this to my loc-line

Geoff · 04-18-2007, 08:45 PM

if the eductor is closer than 3" from the surface of the water than it is not working like an eductor, but more like a regular nozzle. in order for an eductor to work properly it needs a lot of back pressure behind the inner eductor nozzle. without this back pressure their will not be enough of a venturi effect to counteract the loss in head pressure of the inner nozzle for the pump. this is why high head pressure pumps work best.

if i put the same eductor on a Mag 12 then on a Velocity T3 there is huge difference in the flow pattern and total flow in the eductor. with the Mag 12 i can put the eductor within 2" of the waters surface. the eductor on the T3 i can not get with 3" of the surface without the eductor pulling in vortexes from the waters surface and spraying air all over the tank.

the T3 is only rated at 800gph and the Mag 12 is 1200gph. head pressure is needed in order to get an eductor to work properly.

i have every combination of store bought an DIY eductors out there. the best are the ones from KTH sales, the true eductors. the long ones. the longer the eductor the more flow it produces the little penductors are nice and all, but the flow is not near as good as the KTH ones. the DIY are even less than the penductors. just not able to get the flares properly. they DIY ones are great at seeing the potential of the eductor with little money.

it takes a monster pump in order to push more than 2 eductors. i think the Iwaki 100 can push 4, now that will be an insane amount of flow!!!

G~

ivgonmad · 04-22-2007, 03:29 AM

Well, with MY VERSION, I am only using a pump rated up to 6.2 psi, and I'm splitting it in two, so its ~3psi or less per outlet and they work perfect.

The reason my eductors work with lower pressure pumps than the comercial versions has to do with the size of the hole on the outlet nozzle and the design of the body.

You see... the function of the eductor is to create a high velocity jet that creates a vacuum when it hits the low pressure area that is created by the vents around the body of the eductor.

The ones sold comercially are modifications from industrial mixing eductors and are designed to use high pressure pumps with low outputs (high PSI, low GPH), I designed mine to work with less pressure (lower PSI), utilizing the speed that the water has gained from the pump, instead of generating the velocity needed to create the vacuum from putting presure on a very small outlet hole.

Think of it this way....

A truck (high pressure pump) can handle a lot of weight (high pressure) but cannot go very fast (low GPH).

This is why industrial eductors are designed to generate the high velocity jet needed to create the vacuum effect.

A sports car (circulation pump, Powerhead) can go very fast (high GPH) but cannot handle a lot of weight (low pressure).

Since the eductor needs a high velocity jet to work, we utilize the jet that the un-restricted or slightly-restricted output from the pump is generating instead of creating the fast velocity jet by putting pressure on a very small outlet.

Make sense? LOL

Geoff · 04-22-2007, 08:04 AM

sorry, but the laws of physics do not work that way.

you cannot create velocity without increasing pressure through a given pipe diameter. without any pressure behind the nozzle there will not be an increase in velocity out of the eductor nozzle, no matter what pump you use.

as you increase the velocity you are creating back pressure to the pump. this back pressure reduces the flow the pump can produce. with a low pressure pump this makes the eductor less usefull. you will actually be pumping less water than if you had nothing on the outlets.

the following experiments i used to determine what worked and what did not. what method are you using to determine the differences in flow?

a simple experiment to try is this. take the eductors off of the outlest. now move the outlet as close to the surface as you can and note when a small vortex forms above the outlet. now put your eductors back on the outlet and try the experiment again. note when the small vortex forms. it should be significantly lower than without the eductor.

another experiment is to put a small stainless steel washer on a string and dangle it in front of the outlet. with the eductor on it the washer should be deflected a lot further away from the outlet.

another experiment is to put an airline tubing next to the outlet. blow air through the airline tubing. the difference between blowing air into the tube next to a working eductor and a non-working eductor is quite noticable. a working eductor will completely break up the incoming air and spray a huge cloud of fine bubbles through out the tank. an eductor not working properly will just spit out air at the end of the eductor nozzle, it will not completely fill the tank with bubbles.

i have been playing with eductors for a couple of years now. i have tried all kinds of different pumps and different nozzle sizes. the $2 eductor in the link above allowed quick testing with a variety of pumps.

i did find the lower the head pressure the pump can handle the larger the internal nozzle needed to be in order to keep the flow coming out of the eductor close to the pump running without any eductor. the smaller the inner nozzle the more the back pressure killed the flow and the eductor was actually causing a reduction in the amount of flow through the tank.

G~

ivgonmad · 04-25-2007, 04:08 AM

I never said it didnt increase the head pressure or that it required no pressure to function, I just said that they require less pressure to function since the orifice where the water exits the eductor is larger than any of the designs I've seen before.

You are right pressure pumps are the ideal pump to use with an eductor but these eductors are simply a modification of other designs and are made to function with much less back pressure on the pump, therefore a weaker pump can get a decent eduction effect.

ivgonmad · 04-25-2007, 04:12 AM

Have you watched the video provided in the link up top?

It shows how the eductor can suck air thorugh the holes and put bubbles everywhere just like you said they should.

Is this not enough proof?

Geoff · 04-25-2007, 11:36 AM

sorry, i did not see the video the first time i looked at the site. the problem is that you are prolly getting less flow total out of the pump w/eductor as you would with pump alone. any amount of head pressure that backs up on the pump significantly cuts down on the amount of water that the pump can push. if this flow gets low enough than the multiplier effect of the venturi principal will not be greater than if the pump was allowed to pump free of back pressure. as you increase the size of the inner nozzle the velocity of the exiting water decreases causing less venturi effect. your multiplying effect goes down significantly. this is shown in your video. you have to nearly put the eductor at the waters surface to get it pull in air. i can not put my eductors within 3" of the waters surface because of this. this is an a pump that is not even rated at 600gph at 0' of head!!

when i tried my Mag 12 on an eductor like yours i got the same results you did, but they just did not compare to what i was getting with the pressure pump, or even with the Mag 12 running free. with an eductor on a Mag 12 i did see better penetration in the water, but less total flow. the velocity was higher out of the eductor, but the flow in the lower parts of the tank was not as strong. i was also not able to put corals as close to the nozzles with the eductors. the velocity out of the eductor was to high. the fan pattern of the eductor was not acting properly. the eductor on the Mag 12 made a long bubble cone, while the eductor on the Velocity T3 made a wider bubble cone when placed close to the waters surface.

i am guessing you did this with a number 3 little giant pump. looking at the specs for the pump, you were not getting over 500gph out of each nozzle. at 5' of head pressure (i am assuming the pump was on the floor since it i did not see it in any of the pics) the 3-MDQX-SC is only pushing about 900gph total. splitting this in two will decrease the total flow even more due to tubing head loss. adding the eductors on the end of each nozzle would increase the head pressure another 1psi each. which is needed to pull water in around it. 1 psi is equal to 3' of head pressure. the LG is now only pumping around 400gph at 12' of head pressure. that means 200gph out of each nozzle. if you are lucky you are getting a 2X multiplier from the eductor. that puts your total flow at around 800gph if lucky. you would prolly be better off without the eductor. if you were to use one eductor than you may see an increase in total flow over what the pump is rated for. you would be getting more than 1psi out of the eductor at around 9' of head. that could be around 1500gph of total flow. not to bad. this is a pump that does have marginal head pressure though. around 14' of head pressure.

with a Velocity T1 at 20' of head pressure is pumping over 300gph. for each Psi increase you get roughly a 1X multiplier. this is at least 4X since the pump can actually pump up towards 26' of head pressure. so even at 4X the 300gph is now 1200gph out of the T1. the T1 does not really start losing flow till over 22' of head pressure.

both pumps cost around $150.

there is just a lot of math that goes on in figureing out eductors and pumps. if all pumps could use eductors than all PH would come with eductors mounted on them. the new craze would be eductor PH and not propellor PH.

i have just put a huge amount of effort into eductors. i also thought i had found the Holy Grail with eductors and smaller pumps. it was not till i started reading up on how they worked that i realized that it has already been figured out a long time ago.

G~

ivgonmad · 04-26-2007, 03:27 AM

I know I am getting less output from the pump by putting pressure on the outlet but that loss is quickly regained by the eductor generating a greater amount of water movement. The thing is, my outlet is quite large, larger than any of the eductors out there, at 7/16" (almost 1/2") it does not require much pressure to function properly. Its not like I didnt do my homework before I started this project.

I wish I could really show you how much water my eductors are displacing with only about 400gph coming from each outlet... You would be surprised!!

Yeah, I agree my pump is not nearly what is the ideal pump for any comercially available eductor but it works great with mine. Can you explain how I have at least 1000gph of water being displaced from each of my two eductor outlets?

Please give them a try, It is very easy to put together and it is only like $5 per eductor. Then, if you dont see an improvement, you can LMK so I can take this thread down.

ivgonmad · 04-26-2007, 04:01 AM

Will not be posting here any longer. If anybody has any questions about the design, you can reach me at: www.seahobby.com

I am a moderator for the DIY section in that forum.

I am always happy to help any one interested in trying these eductors, just dont need to prove anything to anyone so I would rather avoid the stress of coming here and having to deal with negative people who dont want to try before they start bashing on something.

Good Luck & Fare Well TRT

Twitterbait · 04-26-2007, 04:07 AM

Geoff is not negative, he is simply stating the facts as they are known through the laws of physics. He is one of the most helpful people we have here... and most knowledgable. you may want to re-read what he said.

Geoff · 04-26-2007, 11:01 AM

under no circumstances was i trying to be negative. i was just stating the math behind eductors as well as i know it. if you can tell me where my math is wrong than i will listen. i have been playing with eductors for a couple of years now and have tried all kinds of different internal nozzle lengths/widths, plus different outer nozzle lengths/widths/shapes.

your design is nice and simple. eductors are simple machines. i just feel people need to know what is going on that makes them work in order to figure out if they are right for their tanks.

whether it is yours/mine/production/other DIY eductor they all work the same. they all require a pressure difference in order to work. the greater the pressure difference the more water that is pumped through using the venturi effect.

it am completely for people trying eductors, i think they are extremely usefull on tanks over 4'. they have great penetrating power through the water. they are super simple to make and test on the pumps they have.

G~