venturi what am i missing

[scuba_steve]

seeing how maxi jets suck air and water together going into a seaclone skimmer i tried to set up a magdrive pump to do the same thing but just the littlest air greatly decreases the amount water am i missing something or are magdrives not made for this?? kinda lost!! made a skimmer and trying to get away from using an air pump !! any ideas would be a great help !!

 

[Guest]

The only thing I can think of is that the air has to be after the return. It should not slow the flow though. If it does not have a venturi input, you would have to drill a hole just after the return, and attach the airline... This should create the suction for air...

 

[scuba_steve]

ummm ok which leads me to another question !! i have a basic skimmer made by aquatic life support and using a rio 2500 to power it and that has a air line attached right at the neck of the main input side and that sucks air but when i made one the same way instead of sucking air it shoots water out of the air line !! and i dont understand why !! so thought if i used the pump to suck in the air & water that it would work but a magdrive 700gph pumps less water than a maxijet 2500 300 gph does with the same amount of air or close to it !! must be something with the impellers huh??

 

[scuba_steve]

mabe im trying to push to much water ?? and why it would shoot out the air line instead of sucking air !?!?

 

[Guest]

Well, I don't know that... I guess the laws of physics takes a role here. If you have water flowing in a pipe at a high rate, with a reduced outlet, and you put a hole in the pipe, water would spray out of the hole... If there was no resistance on the other end, it would suck air in the hole.. Kind of the same way an airbrush works... air flows through the tip drawing paint from the cup through a tube...Also, is the airline above water level?

 

[fishfreek]

ALso if the ventri is to far below the water level it can lose effectivness. This is something that with the seaclone is in the instructions to make sure the PH and the ventri is now more than X distance from the top of the water.

 

[scuba_steve]

yes the air line is above the water and it a 1/2 " line from pump to skimmer body which is a 4" pcv tube so no reason i can think of why it wont suck it only squirts water !! i thought that mabe due to the 4" skimmer body being like 3' high might add to much back pressure and why it does that but i also have been screwing with my seaclone to make it work better and drilled a hole at the neck on the feed side and that spits water out as well !! thought that if i could have it suck air that way it would alow the full flow of water from the maxi jet !!

 

[scuba_steve]

just funny how something so simple so i thought could be such a head ache !! but like timbo said "I guess the laws of physics takes a role here" just think that it cant be that hard !!

 

[Guest]

It is funny.. I worked for a Jacuzzi company and we built Spas.... Now... There isn't rocket science in them either... If you have ever relaxed in one, you should have noticed that there is or usually is, a screw cap on the panel that when you open it, air is let in, and you get the mix or air and water to soothe those aching muscles... LOL.. Now.. When we plumbed those, we just cut a hose and placed a T in the line and ran it to the screw cap...Simple operation and I never saw water come out of the screw cap... Now I know that the Venturi Skimmers work the same way. Even on my Penguin PH's, the venturi is placed right on the mouth of the return and it works great.... On a Mag pump I would think that if you had a hole on the return side of the pump as close to the mouth of it, it should work flawlessly... I think you have ventured the routes, I am just trying to keep my sanity in check as I ponder your situation...

 

[Guest]

Whoa,, I just noticed something,,, You said 4" pipe 3' tall? There is your problem...
YOu need a Mag 12 to push that baby....

 

[scuba_steve]

hummmm i can try that wouldnt hurt drilling right into the casing on the pump its self and see it it would pull air and if not the jb weld it closed hehehe thanks ive been working on this and finally gave up and need to ask someone but thought i was smart enough!! guess not though lol should see me drive wait till im 50 mile out of route sometimes before i stop and ask for directions lolol a guy thang i guess

 

[scuba_steve]

that big huh ?? hum might cut a foot off it then and see what it does then !!

 

[Guest]

Oh I was guessing on the Mag 12 thing, It just seems like a lot of back pressure.. Just curius, do you have the skimmer on a 3/4 return to the sump?

 

[loganj]

You can use the Maxi Jet venturi on a Mag Drive pump. Premium Aquatics sells them for less than $5.00. You'll have to add a couple of PVC fittings to get a tight fit though. Or...you can get a Kent venturi in 1/2" or 3/4" for less than $20.00. Or...see my posts in the DIY forum on a DIY venturi. It actually worked quite well. I agree with Timbo though that you need a pretty strong pump for that size skimmer. If you DIY an air intake into the pump inlet, you should also plumb in a regeneration line which will recirculate some of the air/water mix through the impeller...you'll get finer bubbles that way. IMO, the venturi on the pressure side of the pump is the best way to go. It will require less adjustment and will give you better flow. My DIY venturi is made from readily available parts from Lowes and requires about 20 minutes to assemble with minimal mods to the parts. I'll try to dig up the post and edit it in here for you. EDIT: Here it is:
http://www.aquariumadvice.com/viewtopic.php?t=2913&highlight=diy+venturi