Great Venturi Design

Stuart Chignell

I went to bed last night and had a conversation with my wife last night which went something like this:

Sarah wrote:

Whats happening on the forum?

Stuart wrote:

Theres a big discussion going on about FT aeration.

Sarah wrote:

THat's right I want a paddle wheel

Stuart wrote:

No you don't, it would get water everywhere.

Sarah wrote:

What do mean?

Stuart wrote:

The paddle wheel isn't some gentle water feature gently and rythmically turning and providing a nice background noise of splashing water. Its a wheel onnected to an electric motor that spins at ninety miles an hour and sprays water 20m in all directions. They are designed to aerate ponds not tanks. The water droplets as they travel through the air pick up oxygen and fall back into the pond thereby replenishing the oxygen in the pond.

Sarah wrote:

Oh. What about a fountain?

Stuart wrote:

Yeah that would work but for it to be efficient the droplet size needs to be small so that the surface area of the water exposed to the air is large. The only way to do that with a fountain would be to restrict the fountain head so that the pressure would increase which would decrease the droplet size. Thats the sort of thing the discussion is about.

There is this guy who would probably say that restricting the flow of the pump and pressurising a fountain creates a pumping inefficiency and is therefore a waste of energy and therefore inefficient and therefore has no place in AP.

Sarah wrote:

Its got a place if I want a fountain and I can afford the electricity.

Stuart wrote:

Yeah but he would say that all systems should be designed to maximise energy efficiency for the sake of the planet and stuff.

Sarah wrote:

Ahh... ....what a load hippy crap.

hygicell

thanks for this absolutely hilarious intermezzo,
Stuart
kind of puts things
or rather discussions into their right perspective:
it should all stay relaxed and funny

but isn't your signature
proof only exists in mathematics?

don't be offended
I second your signature more that you can imagine

would love to meet Sarah
not sure if she would like to meet an old hippie
but surely she would hide her reluctance and listen to the rantings of this old hippie

enjoyed your post
thanks

frank

Sleepe

Vaguely on topic, out of the link I posted:-
"during low atmospheric pressure conditions, e.g. stormy weather, oxygen solubility decreases".
For those who wondered why their fish behave slightly differently when its stormy.

Sleepe

And just to make it more interesting.
If you have a green FT, its a hot cloudy day with a significant low
increase you aeration or you are in HSM very quickly.

RupertofOZ

hygicell wrote:

the Venturi principle needs pressure to allow it to work
this pressure can come from a pump or from gravity, which in that case is your pump

Well given that a venturi displaces a percentage of flow... then I have to conclude that gravity not only sucks.... but that its obviously bloody inefficient... :mrgreen:

RupertofOZ

Seriously though... most people would employ some sort of venturi "effect" on their return line.. either sump or tank...

Or even as a riser in their siphons.... and even in the picture posted by EB... although the water may be being pumped... the airhole venturi is drawing air into the downward water column.... isn't this essentially the same as a "gravity" fed venturi....

And regardless.... given that the vast majority of siphons used in AP are "gravity" fed....

Then surely... they do have a place in AP??

Sleepe

Another link http://www.fao.org/docrep/x5744e/x5744e0m.htm

hygicell

Sleepe wrote:

Another link http://www.fao.org/docrep/x5744e/x5744e0m.htm

thanks, Sleepe , for again a link that contains a gold mine of information
and of data

maybe, no, probably the most relevant link on the subject of aeration I have ever encountered

I have not studied it in depth yet

so some of the information on it might prove me wrong

I would not mind that

as I have been on a constant quest for either confirmation or correction

please all study this document if you have the time for it

as I admit to be somewhat biased and might only see the confirmations and overlook the corrections

frank

hydrophilia

Sleepe wrote:

Another link http://www.fao.org/docrep/x5744e/x5744e0m.htm

Good stuff. Thanks.

RupertofOZ

Figure you may be interested in one of the early chapters as well Frank ...

http://www.fao.org/docrep/x5744e/x5744e09.htm#TopOfPage

If you want to read each chapter.... substitute the last character (before the .htm) in "x5744e09.htm".... with a value from 1-9... then a-z ..... :wink:

hygicell

Thanks, Rupert
incredibly interesting link
but I feel a bit overwhelmed
in Flemish we say:

Quote:

ik zie het bos niet meer door de bomen

translated:

Quote:

I can't see the wood through the trees

I admit to be an efficiency freak :geek:

and have changed my signature to show that

but I am not a calculation freak
too lazy for that :geek:

however, these equations might come in handy sometime

so sincere thanks

frank

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Great Venturi Design

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