Cone or not to cone..., that is the question!

[tntneon]

The formula does not aply to a cane shape! It is for a cylinder. For a cone we must consider the changing area of the base to calculate the average pressure. In a cone, the pressure will increase or decrease in relation to the changing volume of the increments of the cone in relation to gravity.

did I explain that right?

The formula for hydrostatic pressure is p= m (density) x g (9.81) x h , it doesn't matter witch shape it has , really trust me on this one
I work on every day basis with industrial pumps (process engineer) , coloums and other stuff.

And one other misconception about centrifugal pumps is that they would draw more current when pressure is higher ---> this is also not treu.
If you close the discharge side of an centrifugal pump , pressure rises ,the flow decreases and the thus the labour ---> reducing the current.
If flow is completly reduced (this is also not that good for pumps), pressure is now at max, you'll see that the pump then draws the least current , and when discharged fully open you draw more current .

greetingzz tntneon

 

[Kolognekoral]

The formula for hydrostatic pressure is p= m (density) x g (9.81) x h , it doesn't matter witch shape it has , really trust me on this one
I work on every day basis with industrial pumps (process engineer) , coloums and other stuff.

And one other misconception about centrifugal pumps is that they would draw more current when pressure is higher ---> this is also not treu.
If you close the discharge side of an centrifugal pump , pressure rises ,the flow decreases and the thus the labour ---> reducing the current.
If flow is completly reduced (this is also not that good for pumps), pressure is now at max, you'll see that the pump then draws the least current , and when discharged fully open you draw more current .

greetingzz tntneon

OK, it has been a while since I was in school, but, why, if I place a ventil narrowing a pipe, does the liquid flow rate change? If this is part of the constant pressure equation, I missed it. Of course, we are not talking pure water, we are talking a water-gas mix. Pure water doesn't compress very well, as I recall!

 

[mkengr45]

OK, it has been a while since I was in school, but, why, if I place a ventil narrowing a pipe, does the liquid flow rate change? If this is part of the constant pressure equation, I missed it. Of course, we are not talking pure water, we are talking a water-gas mix. Pure water doesn't compress very well, as I recall!

It is not constant pressure, you will have a pressure drop going through an orrifice or a narrowing in a pipe. I believe you use bernoullis eqn for this. You are getting mixed up in terms of constant pressure vs constant flow. Think back to conservation of volume principles. It has been 6 years since finishing my masters in mechanical engineering so I may have forgotten some stuff.

 

[tntneon]

Yes if you close a valve in the discharge of your return line , you lower the flow , but the pressure before that valve will increasse.

You are correct that skimmer pumps are a bit more fincky , as they suck up air .
If you open a discharge of an skimmerpump it will increase fluid velocity in the suction of the pump and the venturi effect that sucks air in will increase.
at the same time the density of the water is lower (due to the air) so current will stay fairly the same or increase only a little bit .

for instance : if you dial your level in your skimmer up ,then there be also a little bit of elevated hydrostatic pressure on the pump---> lower fluid flow/min. = lower velocity in suction pump ---> will decrease the air suction a little bit .

greetingzz tntneon

 

[mkengr45]

OK, it has been a while since I was in school, but, why, if I place a ventil narrowing a pipe, does the liquid flow rate change? If this is part of the constant pressure equation, I missed it. Of course, we are not talking pure water, we are talking a water-gas mix. Pure water doesn't compress very well, as I recall!

flow rate and velocity are not the same thing.... (Vel.*Area)1=(Vel.*Area)2

hard to show without some equation editor to use proper notation

 

[tntneon]

It is not constant pressure, you will have a pressure drop going through an orrifice or a narrowing in a pipe. I believe you use bernoullis eqn for this. You are getting mixed up in terms of constant pressure vs constant flow. Think back to conservation of volume principles. It has been 6 years since finishing my masters in mechanical engineering so I may have forgotten some stuff.

It is still not forgotten ... :wildone:

 

[mkengr45]

I guess the info is still in my brain, just takes a bit of thinking to retrieve it

 

[Kolognekoral]

I guess the info is still in my brain, just takes a bit of thinking to retrieve it

Yeah, OK, it's 30 years for me!

TNTNeon, thanks for taking the time,

 

[Beaun]

Good purchase

There was a study done in regards to skimmers. Its a long read but as you will see the Alpha cone performed as one of the worst skimmers, but yet the BK mini (non cone, far from one) performed the best.
http://www.advancedaquarist.com/2010/1/aafeature

You fail to see that in the end, even though some perform better than others, they all perform more or less the same. In the end with skimmers, pick one with the qualities you like (footprint, price, size, noise level, self cleaning, ease of use...)

Our data show that there are not compelling or remarkably large differences in measurable skimmer TOC removal metrics among the seven skimmers tested, although the Reef Octopus 150 consistently underperformed compared to the other skimmers. However, in the larger picture, it is equally apparent that if an aquarist runs a skimmer continuously (24/7), then any of the skimmers tested would perform adequately in terms of rate of TOC removal

 

[tntneon]

That's true , noise level is one of my priority parameters in choosing a skimmer

-I also read the article , but it speaks about TOC removal .
Is pariculate matter also defined here as TOC ?

-Because i see my DIY square cone skimmer pulling tonnes of gunk out of a overall 35 G bacterial driven system .
-My DIY cone it seems to be a little more sensitif , when you try to adjust level in skimmer , but then the skimmer body is fairly small in comparison to the pump that is feeding the skimmer (atman 2500 ).
Foam rises beautifully to collectioncup only pump is a little bit noisy .
Therefore my next skimmer will be an BK 200 or BK 200 cone ?

Leaving us still with the question to cone or not.... ??? :lol:

greetingzz tntneon

 

[ksed]

That's true , noise level is one of my priority parameters in choosing a skimmer

-I also read the article , but it speaks about TOC removal .
Is pariculate matter also defined here as TOC ?

-Because i see my DIY square cone skimmer pulling tonnes of gunk out of a overall 35 G bacterial driven system .
-My DIY cone it seems to be a little more sensitif , when you try to adjust level in skimmer , but then the skimmer body is fairly small in comparison to the pump that is feeding the skimmer (atman 2500 ).
Foam rises beautifully to collectioncup only pump is a little bit noisy .
Therefore my next skimmer will be an BK 200 or BK 200 cone ?

Leaving us still with the question to cone or not.... ??? :lol:

greetingzz tntneon

Here is an article, in which Ken also wrote in regards to how efficient skimming is in removing bacteria.
http://www.advancedaquarist.com/blog/2011/3/aafeature

 

[DeathWish302]

I know this is an old thread, but Ken gave a speech a couple years back with the skimmer findings. He also mentioned he tested Sanjay's diy skimmer and found his "less-than-crafty" attempt perfromed better than a prefabbed unit.

I've designed and built several skimmers and I can say in the end they all performed the same function. I don't agree that you get what you pay for, as my $180 skimmer has outperformed all skimmers in the same size class. It's now time to either replace the DIY QO3000 pump or buy a new pump so I'm leading towards a SRO 3000. Skimmers require alot of trial and error, but I'm sorry in saying there is no way they cost $700-1400 in prototype costs upfront. You can argue this point all you want, b/c if it did you would be paying more for a sports car than you did for a house. It doesn't equate for the engr input vs. output. Period!

 

[Reefnooblet]

Got my skimmer! it was on back order for 3 weeks..