how do i force feed air to a venturi skimmer pump

[three90s&125sump]

That's about it. I tried to do it by hooking an air compressor up to the air inlet in the venturi and at very low pressure the pump would keep going but it produced less air bubbles and as I increased the air pressure it would just stop pumping with out ever increasing air injection into the skimmer beyond what it would do with out the compressor.

[jonnosteams]

I would think that forcing more air would do just that... force more air, but less water through.

Could it have been enough air to stop the impeller? I would think that increasing the air inlet diameter would be the only way.

Have you measured the intake flow?

Isn't it a combination of air AND water that creates the bubbles?

Just throwing questions out there to get the hamster running. May help get someone else's hamster running as well.

[jonnosteams]

Any way to increase the speed of the impeller to compensate for the increase in air to water ratio?

[Loverotties]

Maybe change the size of the jet on the venturi.

[three90s&125sump]

Well there is a mod kit for the orca that involves an alita40 air pump. I don't know what all is included in that but I wanted to do a test on it before I shell out 200 bucks for a mod that may not make that big of a differance. So it is possible.

[Geoff]

not sure why. the only reason why i would think you would need to add air to a venturi styled injection system is if the injector is starved. as in the air tube leading to the venturi is to small. if there is not enough water flow through the injector than it really will not matter how much air it can get the bubbles will not be small. in order for a venturi valve to work properly the water flow has to create strong low pressure area to pull the air in and atomize it because of the change in pressure.

i thought Orca skimmers had a mesh/needle wheel pump? if this is the case than the added are going into the venturi is not for creating the atomized bubbles put to get more air itself into the pump to chop them up.

G~

[three90s&125sump]

Orcas do have a needle wheel but the pump is not powerful enough to over come 6 foot of head to draw the air into it. It works fine on the skimmer when it is working at 3 foot of head but it fizzles out before I get to 5 foot. Maybe you have a better solution? Geoff is going to be working overtimes with randy gone.

[Geoff]

why have the pump at the bottom of the skimmer? could you put the sump/pump up on a platform and have the skimmer on the floor?

the only other solution would be to get a bigger pump and modify it. if the pump is not creating enough of a pressure gradient at the venturi because of the pressure, than pumping air into the venturi would not help.

maybe you could make a pre-chamber for the venturi valve. connect the air intake for the venturi to an acrylic cylinder that is as tall as the skimmer. let it fill with water. run an air pump into the cylinder with an airstone in it. that way when the skimmer is on it is pulling in already injected water. definately not an elegant solution.

G~

[three90s&125sump]

Originally Posted by Geoff

if the pump is not creating enough of a pressure gradient at the venturi because of the pressure, than pumping air into the venturi would not help.


G~

I does help, the vacuum from the needle wheel is only so high. If you use an external pump to push the air down to the level of the pump, it only has to creat enough vacuum to pull it into the venturi. Think of it like sucking air through a hose while your under water, you can easily do it at 1 foot of head (as if your snorkling) but try it at 4 feet of head... Not so easy. Now if you pump the air down to a diver that is 30 feet down he can breath... Like divers used to dive before the invention of SCUBA gear.

Putting the pump up at the level of the top of the skimmer doesn't help either. Now the pump has to push the air down. The air doesn't want to go down and the farther down it is the more it wants to go up. So what ends up happening is the pump will lose prime and spin an air pocket.

As far as I know the orca is THE most powerful needle wheel pump on the market. Now I could get a hammer head and modify it but according to the reeflow website (I think that's where I saw it) the alita40 air pump and the orca pump combined is 175 watts and will do aproximatly 3500LPH of air at a 7 foot head, while the hammerhead (which doesn't really have much more head capability once the impeller is modified) will run me around 360 watts and will prolly not produce anywhere near the air injection the alita40/orca combo will do.

What I would like to do is take a panworld 150ps and force feed water to the orca while force feeding air to it as well. Use the panworld for water supply, use the alita40 for air supply and use the orca (or a higher RPM motor) to mix them together. If I didn't have to pay the power bill there would be some merrit to that.

I am going to try a gate valve in front of the venturi.

[three90s&125sump]

I just checked, its at www.aquacave.com. My numers were really close to what it says there. Go there and check out the orca pump under needle wheel pumps. It gives all the numers there.

[Geoff]

i was not thinking of still running the skimmer input to the bottom of the skimmer. that would create the same amount of head pressure like you are saying. i thought you would move the skimmer inlet up to the level of the pump on the platform.

are you the one doing the mods on the Orca pump? if you can fill in some of the needlewheels holes in the impeller that should increase the power of the pump. do you have a link to how the impeller is moded? if you were to do the mod yourself, you could play with the it till you got it the way you wanted it. maybe mod only a few of the blades leaving the others untouched. this should not degrade the bubble making capabilities of the Orca that much if at all. the higher pressure gradient should help in getting finer bubbles. hopefully it will counter the little less chopping going on with the impeller.

G~

[three90s&125sump]

The only impeller mod I'm wanting to do is either a mesh mod or a fishing line mod. I have done almost no research on it. I wanted to look into the alita40 addition to the orca first.

In all honesty, the skimmer is a massive beast as it is and will have 0 (zero) problems keeping a 225 gallon tank clean. I am extremly happy with its performance and I highly doubt that anyone could make a better one for less money. I have 360 bucks invested in it 260 of which consists of the cost of the pump.

My only issue is that I want to add the second chamber that will bring the total skimmer height to 7 feet but when I put it on the air injection diminishes to the point of near uselessness. To make a guess... it goes down to around 700LPH less than 1/3 of what it does at 5 feet.

I do get a few bubbles that are larger in diameter, around 1/8 inch and they do cause a little turbulance in the riser tube I would like to eliminate. I would think that a ring of mesh on the outter edge of the impeller would fix it.

[three90s&125sump]

Here is a pic

[Geoff]

head pressure and needle wheel pumps do not like each other. as you have found out once you get above 4' of head pressure it gets hard for needle wheel pumps.

i wonder if you could add a small booster pump somehow in line with the Orca. just give it a little oomph. it would not take much.

G~

[Hop]

Is the clear hose the air intake?