Venturi questions

[Kittikity]

We have a 20 gal tank that we're going to make into a reef tank.. At first we were just going to do a FOWLR but then I fell in love with the corals.. I plan on making a DIY internal trickle filter, a hang on the back refugium, and a hang on the back counter-current protein skimmer..

The powerhead/pump I planned on using for the skimmer comes with a venturi injector.. I got curious about how exactly the venturi skimmer moves the water through but haven't been able to find my answer exactly.. I know the venturi type needs a pump to power it.. I'm pretty sure that the pump has to be before the venturi valve.. It goes through the pump, through the venturi valve, into the reaction chamber, the foam goes up to the collection cup, the water goes into the main body of the skimmer, and then out the outlet..

Here's where I'm confused.. How does the water get from the bottom of the skimmer back up into the tank? Do I need a second pump/powerhead for this purpose? Or is there some mechanics of the internal physics that I'm not aware of? Or am I just thinking the pump goes in the wrong place?

Please help me understand.. It actually made it hard to go to sleep last night because I had this stuff swirling around in my head..

Jacquie

 

[cindre2000]

Physics!

Think of the skimmer as a bucket you are filling with water. The hose pours the water into the bucket and the bucket fills. At some point the bucket is going to overflow. However, you have a drain the in the bottom/side that leads the a vertical pipe on the side of the bucket. The pipes height is lower than the buckets height, therefore, the pipe overflows instead of the bucket: and you can direct the pipe. If you turn off the hose, the bucket's water level will level to the height of the pipe.

 

[Kittikity]

So the skimmers water level has to be slightly higher than the return to the tank? Before, it just didn't make sense that the water in the return tube would go against gravity on it's own.. But I understand the need for having things at different heights from when I used to syphon my old planted aquarium.. Your bucket example does help me envision it better.. Thanks very much..

Jacquie

 

[Anonymous]

Venturi skimmer typically does not have counter-current type. CC skimmer is almost always associate with those that use air pump for generating bubble with the help of an airstone. In venturi skimmer, there is no airpump, no airstone.

Anyway, the water inside the skimmer just overflow out to the tank as more water is pumped into it by the water pump.