Venturi before or after pump?

[Tampaman]

I have an old school Euroreef skimmer with a Mag 9 as the pump. It has the fractioning impeller and comes with venturi tube for the intake side of the pump. Would I get more flow and air intake by placing the venturi between the pump and the skimmer, akin to how Lifereef sets there's up? I have great dark skimmate, but think It could be pulling more.
My levels are all good, so Im probably just fine. But a free upgrade for just a little fitting fiddling seems worth it!

 

[Vette67]

More air is not necessarily better, especially if they are large bubbles. The needle wheels are designed to “chop” the bubbles into the smallest bubbles possible. Small bubbles have better contact with dissolved organics and make those organics float to the top. The Euroreef is an air injector, not a true Venturi, like a mazzei, so you definitely want it before the pump.

 

[Tampaman]

I could make it a "true venturi" real easy though. I dont know how it implies to reefing but either way, your sucking in air from an area of low pressure created by fast moving water. Air injection would seem to imply feeding forced air from an air pump. So its a venturi before or after physically, but you might be correct in the terminology, with "Air Injection" when venturis are place before the pump. Either way, once inside the chamber, the bubbles start at the bottom. So the skimmer knows no different.
It could be more water and air. Lifereef uses Mag 9's on lots of there's. No matter what, I need a gate valve, my model didnt ever have one. Its also like a piece if China...its from 2005 about.

 

[Tampaman]

I was given the ER skimmer in 2008. It has always been operated with a mazzei style venturi. I guess I needed to look up air injection on these old Euro's because obviously we all know how venturis work, lol.

 

[Vette67]

Hey, I am all for customizing equipment. From what I was reading, euroreef was one of the pioneers of the needle wheel skimmer. So I was assuming that yours was a needle wheel. If it is in fact a true Venturi, then it can be placed after the pump. You just want to make sure you are getting that frothy white foam. You don’t want to see big bubbles in the chamber. So, nothing ventured, nothing gained. Maybe try to set it up in such a way that it can be un-done If things don’t go as planned. Otherwise, I’m sure you can buy a true Mazzei and feed that into your reaction chamber. I modified a 48” skimmer I had from the 90’s and bought a bigger 1” Mazzei Venturi for it. I used that for years, until I got my Beckett skimmer.

 

[Tampaman]

I saw your build thread, crazy how different things were in this hobby just 10-15 years ago. Everyones sump, if they didn't have a wet/dry, was a big rubbermaid...probably can still find one in the garage with a hole for a bulkhead. When I received the body of the skimmer it was without pump. And knowing I didnt want an airstone, we created an venturi. I didn't realize until you now mentioned it and I looked around, that Euroreef were the pioneers for needle wheels. No wonder it was free, lol. Its always pulled very dark skimmate though, so solution worked.
Now that im back in it, I couldnt find the original venturi we made, so the fractioning impeller set from Danner comes with what was supposed to be a venturi. It is in broad sense of pressure differentials, but it dose not neck down inside the flow pipe before the air inlet...like the Mazzei per se. Ive been wanting plastic printer forever...this is just 1 more item I could make. But buying a Mazzei would be worth a shot.
And Yes, I would definitely leave myself the ability to try it many ways.
I appreciate it, nice tank btw, your HDPE barrel was fancy by those standards, and a hell of alot tougher than these acrylic beauties!

 

[ca1ore]

Mazzei and Beckett’s after the pressure pump; air injectors before needle wheel pumps. If you’re going to play around with the former, I personally prefer the mazzei .... plus Beckett discontinued the 1408 foamer. I think Barr makes 3D printed replacements but originals are hard to find now.

 

[Tampaman]

Without necking down, technically its not a venturi I read. So the air injectors work due to the same Bernoulii priciple driving a venturi, just not as efficiently since the fluid speed doesnt increase at the neck....in turn...
Hey Danner, that "venturi" you sold me was a fraud ;-)