Pressure Pumps

[haninja]

<span style="color: black;">I keep hearing about pressure pumps to run certain venturi/beckett driven skimmers. I have a couple of questions:</span>
<span style="color: black;">a) what&#8217;s a pressure rated pump and how is it different from, lets say, a Mag pump?</span>
<span style="color: black;">b) all my searched for such a pump returned non submersibles &#8211; &#8220;plumb outside&#8221; kind of pumps like Little Giant. What would be the equivalent submersible/in sump pump?</span>

 

[george]

A "pressure pump" is one that's been specifically designed to focus it's gph flow at higher pressure and thus can have a higher max head (i.e. pump the water higher in the air -- good for sumps in the basement) and drive skimmers that need lots of pressure to run venturi.

That doesn't mean that a regular pump or mag can't do the same pressure, it just means these pumps are usually better at it. For instance, a Mag 9.5 and an Iwaki MD40RLT have about the same gph at 4 feet (800 and 750 respectively), but the Mag has a max head of only 13 or so feet whereas the Iwaki has a max head of over 21 feet. Only the Mag 36 is rated to hit 21 feet of head. The Iwaki will continue to drive hard with more back pressure or flow resistance (i.e. Becketts and venturi) whereas the Mag drops off quickly.

There is considerable variation in pump behavior, though. You need not only the gph to run the skimmer, but the pressure too. One without the other leaves you with a malfunctioning skimmer.

I am not aware of any true "pressure pumps" that are submersible, but that doesn't mean there aren't any. Just not many.

 

[enderg60]

quiet one 4000HH is the only submersible pressure pump I know of. And I use it on my tank to power the skimmer and return(through a chiller, and feed the reactors)

you really dont want to use a pressure pump unless you have to, as in lots of head pressure, powering becketts or eductors and such. They have alot less flow and consume alot more power then other pumps. But when you need them they are very good at what they do.

 

[haninja]

<span style="color: black;">From other forums I got the impression that the same results can be achieved by “overshooting” the skimmer GPH. So, basically if the skimmer performs best with an external pressure rated pump at 900 GPH, you should get similar results using a submersible pump at 1200 or even 1800 GPH.</span>

 

[kwl1763]

It's very inefficent though. If you take a quiet one or Iwaki at 10ft of head equivelent pressure they can turn out ~1000GPH with just over 100W. You would need a Mag 24 to do that same 1000GPH at 10' and that is 265W of power so 2.56 times less efficient and that would translate to more heat, more electricity, etc, etc.

 

[haninja]

This 'head' thing is what I don't get... the pump will be feeding a skimmer right next to it so there shouldn't be any head right?

 

[kwl1763]

It's really equivelent pressure though.

A beckett or injector works on the principle of constricting water into a smal space and having it suck and mix in air. Constricting it in the ways builds up lots of presssure the pump has to push through so while it's technically not from height the concept is still the same and the pressure is being caused by the constriction.

 

[george]

haninja;171872 wrote: <span style="color: black;">From other forums I got the impression that the same results can be achieved by “overshooting” the skimmer GPH. So, basically if the skimmer performs best with an external pressure rated pump at 900 GPH, you should get similar results using a submersible pump at 1200 or even 1800 GPH.</span>

This is somewhat true, however besides the power and heat issues brought up, a hot, constricted pump will also plate out calcium more and possibly become a maintenance issue. In turn, the warmer water will also plate more calcium onto your skimmer.

 

[skriz]

Head pressure doesn't neccesarily relate direclty to linear feet. You can have a one foor run of pipe with 20 90 degree turns; this would have the equivalent of 5 ft head pressure (made up number for example purposes), not one foot. The linear foot head pressure rating is pretty much saying that if you have x, then it is equivalent to y of head pressure. A beckett is equivalent to y head pressure.

Did that make any sense? It does in my head...

 

[haninja]

<span style="color: black;">Make sense now. Basically, head would equal pressure. More head means more pressure produced by the pump.</span>

 

[skriz]

More pressure applied against the pump.

The high head pumps will produce higher pressure.