Back pressure

[Spiffyguy]

How can you tell if you are getting back pressure on a pump? I am setting up some plumbing and using a MJ900. I am concerned a T I am using is going ot cause back pressure. I really won't know intil I try but I wanted to know what the signs were. I know that MJ are not good pressure pumps either. Don't want to burn it up.

Thanks

[Avi]

Well, it's hard to say exactly what would happen, but most likely, in a simple application, if the pump isn't strong enough, you just won't get the result you want. What is the plumbing application?

[Spiffyguy]

I am setting up a mj900 as a return pump for an in tank sump system. I have a bunch of 1/2" CPVC pipe that i am going to use. I could not find a Y to split it off to two locations, so I am going to use a T. I will ahve some hose to connect the pump to the T. I am just concerned the water will either creat back pressure of cavetate (sp?) and create air bubbles.

[Spiffyguy]

here is how I plan ot use it.

http://reefcentral.com/forums/showthread.php?s=&threadid=976398 (http://)

[2NDTIME AROUND]

You will alwas get some head presure on the pump. You just have to size the pump with that in consideration.

[Agu]

<a href=showthread.php?s=&postid=8606642#post8606642 target=_blank>Originally posted</a> by Spiffyguy
here is how I plan ot use it.

http://reefcentral.com/forums/showthread.php?s=&threadid=976398 (http://)

Link doesn't work.

I did something similar with a 160 gph powerhead and it works just fine, distance from the pump to T is about 6"..........

http://reefcentral.com/gallery/data/500/2DSCN1579.jpg


hth,

[Spiffyguy]

hmm odd try this one. http://reefcentral.com/forums/showthread.php?s=&threadid=976398

I am not sure I will be able to get 6 inches but that is similar to what I will be doing. one side will have a longer travel though, about 10 inches.

[Agu]

Found the thread, here's how my internal overflow looks,

http://reefcentral.com/gallery/data/500/2DSCN1589.jpg

It's only a 5.5 so it was tight. Your plan should work fine with the MJ900. My one outlet is also longer with an elbow too but that doesn't seem to affect flow from that outlet noticeably. I would highly recommend the adjustable flare nozzles. Once you get it set up if your outlet is too close to the surface it'll create a whirlpool effect and suck air there.

[Spiffyguy]

i plan on having 2 Mj900s with two outlets each. on set will be a bit above the sand and the 2nd set will be mid to upper tank with Hydors on them to stir up the flow. All outlets will have a couple of loc line if I can swing it so I can direct the flow if need me. I like the idea of flare nozzles on the bottom ones, that way if the flow is slightly dimished the flare will pick it up. I also plan to do one Mj900 with the mod on it right in the center shooting down the length.

[syrinx]

A cheap and dirty- but not inaccurate way to judge head is add 1 foot for every 90 turn or reduction. That would put the head pressure on your piece at 3 ft or so- as one of the restrictiors would be on the pump anyway.

[Spiffyguy]

would having the T free it up though. being as ther eis more than one outlet.

[syrinx]

good question- it does increase flow, but also is a redirection. The fact you seem to be jumping from smaller soft to larger pvc would no doubt help also. I would have no issues with using the pump this way. When you are doing more standard length plumbing, or making a skimmer- that is the opportune time to remember the 90=1foot ratio.

[Spiffyguy]

lol ok. I will run with it and see if I have any issues. I will keep an eye out for bubbles. I guess that can be a sign of cavetating.