Rena: XP? (1 Viewer)

[C3ntury]

Hello,

Does anyone run an XP1 or XP2 on a 20g or larger? I'm just wondering if the pump is strong enough, at 4', to allow the return to be split (1 for spraybar and 2 for returns) and still provide brisk movement?

Thank you

 

[dvs]

I use an xp3 at around 4' of head on my 75 gallon. However, I do not have the return split. I can tell you that the single return puts out about as much as a mj1200 or that is what it feels like anyways. I also have to koralia #4s for added circulation so I wouldn't rely solely on the xp3 for water movement.

 

[C3ntury]

I was thinking of an XP on my 20g at 4' of head just for circulation and maybe a tad bit of chemical filtration, but mainly for added flow. I'm just not sure how much flow it can produce for me and I'd hate to purchase and find out it isn't adequate to my liking...blah :|

Thanks for the info

 

[Hanson77]

I don't think that you are going to get the flow that you are wanting if you intend to use the spray bar split with something else. If you were to configure some sort of lock line set up, you might still get a good amount flow. I had an XP1 on a 40 breeder freshwater set up and it was plenty of movement for that application. I just don't think that if you were using the supplied spraybar and something else that you would get a good amount of flow in both. There are just too many holes in the spraybar to hold any type of pressure for something else.

 

[dvs]

If you are going to use it just for flow, I would instead go with a mj1200. Is cheaper and probably uses a lot less energy. Not to mention the maintenance on a mj is undoubtedly way less than on the XP3. The xp3 is a pain to maintain. I am switching to a sump soon.

 

[Scott]

I was thinking of an XP on my 20g at 4' of head just for circulation...

Pump head really isn't a factor for a canister filter because it isn't just about how high the pump has to move the water, it's about how high the water has to go in relation to the suction. The point is that the pump is moving the water against wieght of the water column. When in a closed loop, like a canister filter, the pressure-fluid height relationship is determined by calculating the difference between discharge and suction height:

Differential Pressure = P2 - P1 = Weight x Density x Height

If the suction (P1) is the same as discharge (P2) then there is no differential pressure and therefor no pump head, this phnomenon is known as "Static Head".

There is however the phenomenon of "Pressure Head" that we must consider. This occurs when the discharge (P2) is in an area of higher pressure than the suction (P1). Typically from a vessel of lower pressure to a vessel o fhigher pressure. In an aquarium this is negligible but I will explain anyway.

If the discharge (P2) is lower in the tank than the suction (P1) it is thus at a higher pressure. A column of saltwater exerts 4.4lbs/10ft of fluid height, therefor a 2ft tall tank exerts .88 lbf at the bottom. Assuming the suction is at the top and the discharge at the bottom, the pump only has to overcome ess than 1 lbf of head and therefor its losses are negligible, however this is rarely the case as the suction is typically located lower in the tank than the discharge.

That's alot of technical jargon and I tried to keep it simple not let it get too dry so let me know if you have any questions. But the point is that head loss is not a factor with a canister filter so you can base the use of the filter on actual pump rating and if that is enough flow for you. You also have to take into consideration that there is "Friction Loss" with every turn (elbows and such) and a reduction in velocity when the discharge is split but these things are minmal as well.

Good luck with your project and if you still want a canister I probably have on I can sell.

..oh, and yes I am an engineer and yes I have extensive experience in this field.