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Discussion Starter · #1 ·
Alright,
so I have my ampmaster plumbed up (Closed Loop), but I am thinking I might be restricting the output a little too much. Here's what is happening. I have 1.5" out of the AM3K to a T fitting where it reduces to 2 1" lines. One of the lines runs into the tank, the other splits to 2 1" lines, each into the tank. I run all of them wide open (3 1" outputs in the tank). If I open the output of the AM3K all the way I get microbubbles in the tank out of the closed loop. If I restrict the output of the AM3K slightly I get no bubbles, but some occational noise out of the pump.

Any ideas on this? Would changing the first T from 2 1" outs to 1 1" out and 1 1.5" out help?

I'm at a loss here, and I really don't want to ruin the pump.

Thanks for the help everyone.
-Reed
 

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hmm only thing i can think of off hand is that it's pulling in air from somewhere. maybe on of the t's has a micro leak, that is sucking air in when it's opened all the way?

i've never plumbed a cls yet, so i could be way off base, just taking a stab in the dark.
 

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Jay has the most likely cause. if there is a micro leak you have for all intensive purposes made a DIY venturi valve.:D

another possibility is that when it is wide open the flow is so great that at the intake small funnels from the surface could be created. you would prolly see a lot more bubbles if this were the case though.

i would check for leaks.

G~
 

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Discussion Starter · #4 ·
DOH! I was hoping that wasn't the feedback I'd get. But then again, the truth is never fun. I will check for leaks in the plubing, as the intakes are down near the middle of the tank & I see no way they could introduce air into the lines.

Thanks guys, really appreciate it.

-Reed
 

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Reedman, your not looking for leaks underwater near the intake you are looking for leaks where the return comes from the pump....if the leak is underwater you are right there would be no air "sucked in".
 

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Discussion Starter · #6 ·
Thanks Dave. I just reread my post and see that my grasp of english is diminishing quickly :)

I was trying to say that the funneling possibility that Geoff suggested isn't really possible in my tank because of how low the intakes are.

I will check all of the exposed plumbing for small leaks. I am guessing I have a very small leak at a joint that is letting a little air in the line when high flow creates enough suction.

Thanks again.
-Reed
 

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Reed.. just go over all the joints with another layer of pvc cement.. goop it on good..

Also, reducing from 1 1.5" line to 2 1" lines is probably adding some restriction..

1.5" line has 1.766 square inches of area...
1" line has .785 square inches of area..
so 2 1" lines is 1.57 square inches.. not a huge difference, but it is some, if you're concerned with head buildup..
 

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Discussion Starter · #9 ·
Yep. I have a little salt creep at a joint. I will clean & dry it, use some primer, then some PVC cement to (cross fingers) seal that baby up.

I don't "design" airplanes, just help in designing airplanes...so please...keep flying :)

I used to use loc-line, but I like the larger outputs better, so I noow have loc-line in the garage with other miscilaneous plumbing parts for the next tank (don't tell my wife).
 

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not sure if you guys know this but when doing plumbing with PVC tubing you use the primer/cleaner on the ID and OD of the joint being glued and make sure the cleaner is competly dry... then goop on the glue on the inside of the joint... after you have pushed the joint togeather as far as it goes always give the tube a 2"- 4" turn (helps the glue seal). learned this doing plumbing on in ground swimming pools for 2 years. Please dont take this as an insult if you have experience at glueing PVC
 

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Discussion Starter · #12 ·
Thanks for the tip Buehlz. I'll use it on the next project.

So I can here air in the pump when I open it up. I am assuming that this means that the air is being introduced on the intake side of the pump (thinking out loud here). Does this make sense??

If that is the case my search for a leak is much smaller.

Thanks everyone.
 

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lol i like using the purple primer and then the cement. cuz it has a purtie color :D

thanks buehlz, i have heard, and always do, twist the joint after htey have been pressed together. but i did not know it should be 2" to 4" i have just always given it about 1/4 turn one way, then 1/4 turn back.

but i have also only glued minimal things thus far. as i'll be gluign together my cls tommorrow, thanks for the advice!
 

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reedman, yup, that's where i would start looking first. if yo udont find anything on the intake side, well then you know what's next :)
 

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Discussion Starter · #15 ·
Alrighty then,

I hate to belabor this, but I checked all of the joints on the intake side of the pump (there aren't many) and found no leaks. I can hear air mixed in the water flow through the pump, so I am confident that the intoduction of air is on the intake side. When I throttle the output back a little I loose the bubbles, but the pump begins to make some noises that I really don't like (I'm thinking it may be cavitating).

Here's my question. For a pump to cavitate you need to be starving the pump, correct? I am running 1.5" plumbing on the intake side and T it off at the end to limit the suction effect (2 1.5" strainers). This shouldn't starve the pump, I wouldn't think.

Please throw out your suggestions. I'm getting real sick of redoing my redone plumbing.

Thanks all. You guys (and gals) are the best.

-Reed
 

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NO NO NO that is a NO NO NO.... my boss would have shot me if he would have seen me twisting it one way then the other... only twist it one way (helps make sure that there are no air bubbles)
 

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Discussion Starter · #18 ·
intake is 1.5", outlet is also 1.5"

I have given up for now and will let my brain rest. I unplugged the pump to prevent any damage until I can figure out what is wrong with it.

Thanks all.
 

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hmm maybe the intake and outtake are too large of a diameter?

what pump is it on (sorry if you already posted that, i'm getting ready for work right now and jsut got out of bed)

i know that pumps havea harder time lifting water through a larger pipe than through a smalelr pipe. ie" 1.5" of water is heavier than 1" or 3/4"

that COULD be the problem. when trying to run at full throttle, it's giving too much pressure back on the impeller to move the water, and causing that noise. could be that it's also chopping up the water too finely as a result, and creating the bubbles? i'm no scientist, so mabe that isnt even possible
 

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Discussion Starter · #20 ·
Jay - It's an Ampmaster 3000. The manufacturer says to never reduce the intake side (makes sense to me) and to try to keep the output side at or greater than 1.5".

I was thinking that the back pressure, due to a reduction from one 1.5" to two 1" at the first "T" may be causing the pump to cavitate (I believe it is when gas is drawn out of the water due to lower pressure areas in the pump). The that has me confused is that all of the cases of cavitation that I have seen related to aquarium pumps has to due with starving the pump for water on the intake side, not restriction on the output.

Ampmaster even says on their site that the AM3K can be plumbed with 1", you just loose some GPH.

Still lost, but the room is quiet and the tank is running with powerheads for now.
 
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