Noisy Closed Loop...

[rstark33]

I don't want to hijack the thread but I am just completing a CL on a new tank and now I am worried.
Using a Mak 4, with has 3/4 inlets and outlets, should I be using larger pipe on the intake side and reducing at the pump? I bought the pump used, so I have no instructions. I planned to run 3/4 in and out, should I bump it to 1" or bigger?

 

[melev]

rstark33, I wouldn't worry quite yet. If you've already completed it, hook it up and observe how it runs. If you notice a problem, then you can try changing the input side to larger PVC as directed in this thread.

 

[reverendmaynard]

I thought I was over doing it with the 1.5"

 

[rstark33]

I have yet to plumb and the tank is dry! It is acrylic so I am drilling for bulkheads on the intake and the returns. Would it be better to use a 1" bulhead and 1" pipe to the pump. If I go ahead and put a 3/4 bulkhead in, then exapand to 1" pipe, would it make any diffrence? I already have the parts for 3/4" so changing would requiring getting a new 1" bulkhead mailorder.

 

[melev]

Rich, you could built the closed loop and hook it up to a trashcan or rubbermaid bin to test your plumbing & pump. That way if it doesn't work out, your tank is still untouched and you can make alterations.

I would think 1" to 1.5" may be best, but as you can see in the post above yours, there are still some variables that have to be worked out.

 

[bassnman11]

You stated you used a single wrap of teflon tape on the pump outlet. I always use at least 4 to 6 wraps over the whole lenght of the threads. I was getting bubbles in my closed loop. I removed the threaded top cap and applied new teflon tape and tightened it lightly with a wrench. No more bubbles. Hope this helps.

 

[reverendmaynard]

Yeah, I wrapped the threads completely. I just meant that I didn't double wrap them or otherwise use too much tape. IMO, too much tape is as bad as not enough.

 

[Pyrojon]

Hmm, the difference between the input through the back vs. over the back had not occured to me.

I think that I will make an attempt to find some time today to swap out my blueline for my QO6000 and see what results I get. i will let you know what I find.

Jon

 

[reverendmaynard]

I bought the parts to redo the intake in 2". Hopefully will be able to install it over this long weekend. Will keep everyone posted.

 

[BigJPDC]

So is it a silly question to ask why the fittings on a Mag pump are 1/2 the size of what is supposed to give optimal flow?

I posted a thread a while ago about my experience with a Melev-style CL build. Plumbing a Mag9.5 with 3/4 worked so well (silent, serious flow) that I couldn't wait to bump it up to 1", which wound up costing me an entire weekend posting and trying different input pipe lengths and inlet designs, etc. while battling crappy performance and what I am guessing is cavitation noise.

Doesn't it seem strange that you plumb with 2x the size and then use a valve to close it to 50%? I like the idea of 'dialing-in' the flows though, and might add that to the next rev of this build.

Hopefully the weather stays nice in NY and I can try some combinations of 3/4 and 1" in\out piping. I'll report back.

jp

 

[rstark33]

JP,
That is what is rather confusing for me too. It the pump needs a 1" input to get the most flow, then why is the fitting on the pump 3/4??? Doesn't the reduction at the input to 3/4 slow the whole intake down no matter how much 1" pipe you have?
Isn't the flow controlled by the smallest point in the line?

 

[BigJPDC]

one of the things I think is that the pump isn't designed for what we are trying to do, and this is one of those things where the wisdom of the fish message boards is driving the tweaking advice - and not at all in a negative way, a lot of this stuff is trial and error.

I'll know more when I replumb the whole thing to 3/4 - if it's quiet I am done and can move onto another DIY piece.

jp

 

[melev]

I believe the Mag pump is designed in this way to create flow via pressure. It isn't a pressure-rated pump, but if you restrict the flow going in and out of the pump, it will run hotter and not push the advertised flow.

And yes, it wasn't designed for closed loop application, but rather for ponds and such.

 

[BigJPDC]

Thank you Melev. It looked like you had such good success with your SCWD\mag5 project I thought this would be a sure thing.

First round of bucket testing with the Mag9.5 - 3/4" in, 1" out. Quiet like a sleeping baby, but a ton of microbubbles. not sure where they are coming from since I have no leaks. I can put a valve on the 1" side (beacuse I have the spare parts) but I'm not so sure the bubbles aren't coming from the intake side and that is where the valve should go.

 

[melev]

Hopefully you can find the source of the bubbles. Was this a freshwater test or a saltwater test? Did you put teflon tape on the threaded (priming) cap?

 

[rstark33]

Do you know if the need to increase the intake is only for Mag pumps. I am using a gen-x Mak 4 for my CL and it has 3/4 in and out. I already drilled the tank for a 1 inch bulkhead for the intake, so that is what I am using, but just for reference, are all pumps designed this way?

 

[BigJPDC]

<a href=showthread.php?s=&postid=7659585#post7659585 target=_blank>Originally posted</a> by melev
Hopefully you can find the source of the bubbles. Was this a freshwater test or a saltwater test? Did you put teflon tape on the threaded (priming) cap?

Freshwater test in the backyard - you have me thinking because the priming cap is just a cap. I can't believe I just cut up the outtake plumbing to put in the valve and it's probably that stupid cap, but I'd want that anyway to control the flow.

One note for you Melev is that I added the T as you suggest with a screw cap (threads tapes) to drain it for removal and when I popped it open I started to siphon the entire bucket - so I'll have to put a siphon break on BOTH inlet and outlet for that to work.

Raining again in NY, Yankees game delayed so no more testing until tomorrow.

jp

 

[melev]

<a href=showthread.php?s=&postid=7659664#post7659664 target=_blank>Originally posted</a> by rstark33
Do you know if the need to increase the intake is only for Mag pumps. I am using a gen-x Mak 4 for my CL and it has 3/4 in and out. I already drilled the tank for a 1 inch bulkhead for the intake, so that is what I am using, but just for reference, are all pumps designed this way?

As far as I know, this is only for Mag pumps, but the more people that post in this thread using different pumps, the more we can document what is actually required vs guesses.

 

[melev]

<a href=showthread.php?s=&postid=7661030#post7661030 target=_blank>Originally posted</a> by BigJPDC
Freshwater test in the backyard - you have me thinking because the priming cap is just a cap. I can't believe I just cut up the outtake plumbing to put in the valve and it's probably that stupid cap, but I'd want that anyway to control the flow.

One note for you Melev is that I added the T as you suggest with a screw cap (threads tapes) to drain it for removal and when I popped it open I started to siphon the entire bucket - so I'll have to put a siphon break on BOTH inlet and outlet for that to work.

I hope your changes make it better and easier to use.

 

[Atomahawk]

<a href=showthread.php?s=&postid=7659346#post7659346 target=_blank>Originally posted</a> by BigJPDC
Thank you Melev. It looked like you had such good success with your SCWD\mag5 project I thought this would be a sure thing.

First round of bucket testing with the Mag9.5 - 3/4" in, 1" out. Quiet like a sleeping baby, but a ton of microbubbles. not sure where they are coming from since I have no leaks. I can put a valve on the 1" side (beacuse I have the spare parts) but I'm not so sure the bubbles aren't coming from the intake side and that is where the valve should go.

If no one minds maybe I can assist. I have done lots of system plumbing and designing central units for retail.

If your getting micro bubbles in your tank and your certain that your not drawing air from an air pump or from the water surface it's most likely caused by a small leak on the suction side (inlet) of pump.That means every glued joint, threaded coupling, true union and valve needs to be looked at. Whats happening is that small gap is causing a venturi and sucking air into the impellar assembly. It dosn't need to be much of a gap or a crack for this to happen. A hair on a rubber seal of a true union will cause this very easily. You won't get water leaking out of this small gap as the velocity of the water traveling through the plumbing just won't allow it out. When pressure is off ( when the system is closed ) you may or may not get a water leak depending on the nature of the gap and where it is. Sometimes this micro gaps close themeselves up when theres no pressure so water won't leak out, making it even harder to find.

How to find the leak? The best way is to put pressure on the plumbing system with air. By capping one end and making an adapter that will allow you to use a really good air pump or compressor ( Be careful if you use a compressor) on the other end you can dabble a mixture of water and soap on every joint and pump housing. Bubbles will form at the faulty joint.

Could it be a leak or a gap on the outlet side ( to tank) of the plumbing?
Yes but most of the time water will drip out on this side so it's fairly easy to see. I have rarely seen it cause a venturi effect on this side, but Murphy's law always applies to anything we do, so dont assume anything.

Just a heads up, if you get air in the system after running your pump for a few hours. The pump housing or a plumbing connnection
at the pump is heating up and expanding a joint just enough to allow air in or water out.