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disaster999
04/18/2009, 09:35 PM
i wanted to modify the air skimmer i have into a venturi+pump skimmer in hopes of creating finer and more consistent bubbles.

the skimmer i have is around 2" in diameter and around 12" tall

i bought a pump with 95gph and made a venturi for it using a tube and epoxy. at first i had the whole too big, around 5/8"-3/4" and it wasnt sucking enough air as the pump is submerged lower into the water(~4", it will not suck in anymore air) so i narrowed the opening to around 3/16" and it sucked air at any depth, but its not sucking nearly enough and i think the flow is pretty low as well.

is there a general diameter of how big i need to make the venturi? this is my first so im just experimenting and see what works and what doesnt

username in use
04/19/2009, 09:16 PM
Id like an answer to this as well.

disaster999
04/19/2009, 11:35 PM
lemme include some pictures
http://i78.photobucket.com/albums/j82/lcc7107/fish/skimmer/DSC_1576.jpg
http://i78.photobucket.com/albums/j82/lcc7107/fish/skimmer/DSC_1581.jpg
http://i78.photobucket.com/albums/j82/lcc7107/fish/skimmer/DSC_1582.jpg

this is before the venturi was modified further. i will include some pics with the skimmer running to show you the bubbles its making

xsquyz
04/19/2009, 11:42 PM
Lets see some bubbles!

One Dumm Hikk
04/20/2009, 01:48 AM
For something that size, you would be better served with a small air pump connected to it with an adjustment valve. Then you can adjust the air flow to get the best results. Its hard to make an efficient venturi for such low flow.

disaster999
04/20/2009, 06:48 AM
yeah, ive been told that a number of times, but seeing how euro-reef can take a similar size pump and transfer it into a bubble making machine, i want to give it a try. granted he has more knowledge and resources on the subject. if i have more time i might achieve something similar...hopefully

anyways, here are some pictures from friday when i first had it setup
http://i78.photobucket.com/albums/j82/lcc7107/fish/skimmer/DSC_1598.jpg

i took the pump apart for a closer inspection and realized the opening for the venturi was way too small. it restricted flow quite a bit which resulted in poor air suction. i opened up the hole a bit till i cant feel the difference with the venturi on or off. heres the result
http://i78.photobucket.com/albums/j82/lcc7107/fish/skimmer/DSC_1602.jpg
bubble size
http://i78.photobucket.com/albums/j82/lcc7107/fish/skimmer/bubble.jpg

Agu
04/20/2009, 12:54 PM
Here's how I modified a skimmer and made a new venturi (http://jjgeisler.com/reeftank2/)

disaster999
04/20/2009, 06:38 PM
sorry, but that didnt really help

disaster999
04/20/2009, 07:03 PM
found this site after doing some research. lots of good info on diy venturis

http://www.randystacye.com/diy_venturi.htm

fishoutawater
04/20/2009, 10:56 PM
I found a nozzle kit at home depot in the pvc section. It's designed to go on the end of a hose and tunnel under sidewalks to run pipe through. It cost about 5 bucks. I used it for my last venturi build.

disaster999
04/23/2009, 11:35 AM
took a video of my skimmer in action. its creating tones and tones of micro bubbles...but why is it not working as good?

http://www.youtube.com/watch?v=mp6nlb4eqVM

disaster999
04/24/2009, 12:30 AM
bump

Reefbox
04/24/2009, 12:33 PM
The air has to go through the pump and get chomped up by an impeller to make really fine bubbles such as in needle wheel skimmers.

stugray
04/24/2009, 12:38 PM
The truth is: In this configuration ( air being ingested on the Input side of a submerged pump ), you dont need a classic venturi design.

Try a small gate valve and adjust for max air.

All that is really required is a restriction on the water intake and air gets sucked in regardless of shape.

A true venturi that is intended to go on the OUTPUT are the types that require careful design.

Stu

Agu
04/24/2009, 09:37 PM
A venturi is mounted on the output side of the pump and has an air intake after the restriction.

Your "venturi"is on the intake side without an air intake. You're getting few bubbles because the impeller is creating turbulence bubbles as the impeller cavitates but not nearly enough to actually skim.

stugray
04/25/2009, 08:41 AM
I didnt even realize that you did not have an air inlet until Agu mentioned it.

Drill through the side of the "venturi" on the pump side of the restriction and insert an air line.
Put a small valve on the air line or tie in a knot to restrict the input a little, then adjust until the pump is pulling a decent amount of water and a lot of air.

Too little water & too much air will cause the pump to cavitate horribly.
This will cause low flow & eventual damage to the pump.

Stu

Agu
04/25/2009, 06:29 PM
<a href=showthread.php?s=&postid=14894282#post14894282 target=_blank>Originally posted</a> by stugray

Too little water & too much air will cause the pump to cavitate horribly.
This will cause low flow & eventual damage to the pump.

Stu

Any air at the inlet side of a 95 gph powerhead well end this way, the venturi and air inlet need to be on the downstream side of the powerhead.

disaster999
04/26/2009, 04:38 AM
sorry for the confusing, the picture i showed dont have an air intake. but i already drilled and have an airline inserted in order for it to suck air and skim.