Skimmer discussion thread
- Thread starter krisfal
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DonW
R.I.P.
I think it changes from day to day and who you talk to. We used to use Escobals formula's back in the diy skimmer rage days. Now that we have more options we shove in as much as we can get away with no science or math needed. Its easier to have to much and just valve it down than not have enough.
Don
robert0762
Well-known member
what is it exactly about a pump that determines how much air it will pull? Ithought it would have more to do with the venturi but from what i gather from this site it doent so can someone crarify this for me PLEASE
Venturi effect is when water pressure drop at the air narrowing inlet cause by the increase of speed of water (distance over time). The faster the water travels over the inlet the greater the air intake because of lower pressure causes air suction. Increase speed; increase air suction. Higher GPH pump; higher flow volume; higher speed; higher air suction.
Speed of water (distance over time) relates to the flowrate (volume over time) of water typically measure in GPH for pumps. Speed of water over a pipe ID (area) will give you flowrate. (Distance x area = Volume)
If you increase the flowrate/GPH with a larger pump while the pipe using the same inlet pipe for water and T inlet for air: more air will be pulled.
I hope this is not confusing. I am not doing a good job explaining it.
robert0762
Well-known member
thats what i know already know I should have frased my ? differently So lets try again Why does a pump pull more air with a mesh mod ? Its not pumping more water is it?
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Speaking from past venturi experience with Fathom skimmer mods, downdraft mod, AquaC mod and the latest mesh mod; they all use a form of venturi.
Fathom skimmer has a venturi hooked up at the outlet of the pump and the air water mix goes into the body of the skimmer and swirls around in uncontrolled turbulence. Bubbles are random size. Old school venturi skimmer.
Based on my forum trolling the last few months and my current built, mesh mod uses venturi to pull air in as well.
Where it differs is the venturi is connected on the inlet end of the pump. Another important feature required to pull more air would be a large volute (cover volume of the impeller) mod.
Below is just my speculation based on my current mod.
Since the outlet end of the venturi is near a enlarge volute and the mesh impeller can shred and/or cavitate; it can suck in more air + mesh mod has higher speed. More volume after the venturi and higher speed meshed impeller in the volute will increase the air pulled.
There is most likely a point of dimishing return of enlarging the volute. I have only one prototyped.
Another feature of the new mesh mod is the bubble plate. It will force all the air/water mix to bubble up in an orderly manner.
One interesting observation on my mesh mod with enlarged volute, is if I opened the air valve completely and suddenly; it will vibrate and maybe stall (unbalanced mesh?). However, if I slowly open or close it will be quiet. I now use a needle valve to get air bubbles of less than 0.5mm that travels up the neck column of the skimmer.
Long answer for a short question. How about that?:badgrin:
