Cloosed Loop Plan?

[BigReepher]

Before I proceed I want to check with the masses to see if there are any flaws in my closed loop plan. Notice the sizes of the PVC. 1 1/4 up and over the tank lip to 1 1/2 on the back side into the pump then 1 inch out into SCWD with 3/4 inch coming out each side. I'm using the 1 1/4 on the inside of the tank because it's less bulky than 1 1/2 and I already had some 1 1/4 SCH 80. Should I use 1 1/2 or 1 1/4 coming out of the mag12 into the SCWD? Do you think this will work well? Any recommendations? This is going on a 75 BTW.

 

[BoomerD]

The big restriction on the whole system is going to be the SCWDS. The ID of those is just over 1/2" I think, so you really don't need to use the large pipe that you have in the diagram if you don't want to. Tou also lose quite a bit of flow with each one of the hose barb adapters you have to use coming into and out of the SCWD as well. You won't really gain any more flow than if you plumbed it with 1" and 3/4" . I did a closed loop with 1" and 3/4" risers, an a Mag 12, and got great flows from the 1" manifolld and 3 3/4" legs into the tank. If it's just a matter of using plumbing parts & pieces you already have, then that's fine, use the larger pipe, but it won't really make much difference in the overall flow because of the SCWD restrictions.
Oh yeah, don't forget to put in ball valves & unions on each side of the pump so you can close the system off to do maintenance on the pump from time to time.

 

[BigReepher]

Thanks for the feedback BoomerD. I'll probably put the SCWD on the return pump instead of the CL for the reasons you pointed out. Also because it's a good idea to prefiltered the water going to the SCWD and it's easier to do that in the sump. I'm trying to picture what your CL manifold looked like, can you give me an idea? Does the prime side look alright? TIA

 

[wooddood]

nate it looks pretty much like my closed loop design, i used 3/4 piping on it all and it works great. plenty of flow. also the prime side looks fine to me, just unscrew the cap to prime the pump. heres a pic of mine.

dave.

 

[wooddood]

and heres a pic of the intake inside the tank, although i drilled 1/8 in holes the slits should should work fine too as long as you dont have any critters small enough to get sucked into them.

dave.

 

[BigReepher]

I made what I thought wouldn't create cavitation. I didn't use a short piece of 1 1/2 right before going into the pump, like I had planned. I think this is what is causing my cavitation. Please take a look at what I have so far and recommend a remedy to the cavitation. Would a piece of 1 1/2 PVC coming out of the second 45 going into the pump do the trick?

BTW looks good Wooddood, wish I had as much luck using the 3/4 PVC.

 

[Scooterman]

Why do you have it up sizing on the intake, Instead use the proper size recommended & that should solve the problem. Reason why is of the larger intake volume, it can't suck in enough water from above, do this and see how that otherwise neat set-up will flow!

 

[dwall174]

Originally posted by BigReepher
I made what I thought wouldn't create cavitation.

Here's an Article that might help you out! A good rule to follow is to have a straight piece 6~10 times the pumps intake dia. So with a 3/4" inlet you should have a 4.5" min. (7.5 would be best) straight section before any fittings or elbows.

 

[BigReepher]

Originally posted by Scooterman
Why do you have it up sizing on the intake, Instead use the proper size recommended & that should solve the problem. Reason why is of the larger intake volume, it can't suck in enough water from above, do this and see how that otherwise neat set-up will flow!

From reading past post, I was under the impression that a larger diameter PVC on the inlet side would help eliminate cavitation. I tried using 3/4 PVC and 3/4 vinyl hose with no success. What size PVC would you recommended? Maybe 1 inch or would vinyl hose be a better choice. I understand what your saying about the pump not being able to suck in enough, I think. Do you mean there is too much water that has to fight gravity and make its way up and over the tank lip? I thought about this while I was planning the CL, but I listened to my brother the plumber who said "it's basically a syphon and the bigger the better". This is also the reason I went with 1 1/4 on the inlet side and 1 1/2 on the back side, to help increase the pull on the inlet side. Thanks for the link dwall, I'm gonna have to go back over it so that I can fully understand the dynamics of cavitation. Thanks again everyone.

 

[BigReepher]

I threw together some 1in. PVC, taped the joints to keep air out and water in and still I get cavitation. Please take a look at this and tell me what I'm doin wrong. Please!

 

[JeepersReefers]

Wooddood,
Have you ever had any noise or micro bubble problems with your closed loop with a mag pump? I had nothing but problems with mine. I tried every suggestion I got off this board and it still was noisy (even the larger sized pipe). I even tried a different mag pump. I finally gave up after a week and $50 in plumbing parts, and bought a few maxi jets 1200 for now.

 

[JeepersReefers]

I think the problem for me was with the mag pumps. Your system looks identical to mine, and your problems shure are. I might try it again some day W/O a mag pump.

 

[BigReepher]

Funny you should mention that Jeepers as I was wondering if the pump was at fault. I took everything off the pump and ran it w/o the PVC just a minute ago, it's noisier than it was a few weeks ago. It sounds like cavitation, but there aren't any micro bubbles. When I put the PVC back on the micro bubbles come back. The bubbles are smaller with the 1in. PVC though. I took the impeller out and noticed a small chip in the magnet. Could this be causing my problems? Looks as if I might have to order another impeller or try another pump.

 

[JeepersReefers]

THe small chip cant help, but i doubt if that is causing all the noise. I tried 3 diffrent mag pumps and had the exact same problem with all of them. Im thinking of the quiet one 4000, but that is a few months away.

 

[BigReepher]

I just ordered a GenX GX4100 and an impeller for the Mag, one of them is bound to work.

 

[JeepersReefers]

Ill keep an eye on this post to see how the genx works. good luck

 

[Dracunculus]

One thing I did notice about your pump is that it is resting right on a solid surface. The noise is dampened quite a bit (at least on mine) by resting it on a mouse pad. I don't hear it at all over the whine of my canopy fan anyway

 

[JeepersReefers]

mine sat on a faom pad on one try and on the carpet on the other 2, so that wasnt the problem for me at least.

 

[BigReepher]

It isn't visible in the photos, but the pump has a foam pad attached to the bottom. The pump sounds like it's pumping gravel, but it didn't sound like this when I first got it.

 

[Scooterman]

BigReepher, try a stright 3/4" inlet abut 6" long going into the pump, then a 90 instead of the 45. Then 3/4 all the way up & over. It sounds like mentiond above that it is needed to get a good suction going. If you decide to use a bigger Pump like mentioned then I'd say you would have it running by now. Look at this photo!