Mag Drive 24 - 3/4" Return Plumbing

[shaunw60]

Hello,

Discovered the loud vibration from my Danner Mag24 is a result of using 3/4" ID connections and return line to the tank. Overflow kit provided with this tank came with 3/4" bulkheads and pipe. Has anyone experience with fittinga "bleed" tee to reduce back pressure on pump and therefore reduce vibration?

Danner recommend 1 1/2" ID for return lines, that is larger than the overflow provided!!

 

[pyro383]

you can use a ball valve to throttle the flow back, put a tee on the return side and dump the extra gph back into the sump. This would be required if you use the 1 1/2" pipe since it allows more gph. Since I don't know what your tank setup is, I suggest using a smaller pump as the overflow can propbably only handel 600gph.

 

[sjm817]

You might as well put a cork in the pump. 3/4" plumbing is a HUGE flow restriction on that pump. Even a Mag9.5 is severely restricted using 3/4".

Why such a big return pump?

 

[JoeESSA]

You might as well put a cork in the pump. 3/4" plumbing is a HUGE flow restriction on that pump. Even a Mag9.5 is severely restricted using 3/4".

Why do the Mag 9.5, 12 and 18 come with 3/4" fittings then?

Just curious.

 

[sjm817]

That's the way they make them. The instructions state to use 1.5" plumbing on the pump. You are supposed to double the outlet size.

The Mag24 actually has a 1"outlet. You may need 2" plumbing on it.

 

[JoeESSA]

Think the standard bulkhead and return plumbing on most Oceanic tanks is 0.75". Mine is, I think. At least the bulkhead fittings are 3/4". Have you heard of 1.5" kits that will work with Oceanic tanks?

 

[sjm817]

You can run 1.5" up to the bulkhead, convert to 3/4", then convert back inside the overflow, room permitting. This is less restrictive than running 3/4" the whole way. A better way is to use a pump that handles head better than a Mag such as an Eheim or an external pump. These pumps dont need the huge plumbing for good flow.

 

[Drakis]

I bought a mag 18 for a return on my 72 gal, BIG mistake!!! Its hard to get to much flow, but its easy to get to much overflow...... I traded it to my dad for a mag 7, much better!!!

 

[forensicdoc]

I am actually thinking about a Mag12 for a return on a 190. The tank has two 1" drains with 24 linear inches of overflow and a 3/4 inch return bulkhead.

I have read about increasing the diameter of the return from the Mag line by at least one size (for example, from 3/4 inch to 1 inch). I wonder whether it makes that much difference if there is only about 3 feet of return pipe between the pump and the bulkhead on the tank (where you would have to reduce to 3/4 anyway). I read you can then increase again after the bulkhead, but that is only for a brief distance also.

Has anybody looked at whether the bother of increasing and decreasing the line diameter for such a short run really makes that much of a difference. Anybody?

 

[JoeESSA]

A better way is to use a pump that handles head better than a Mag such as an Eheim or an external pump. These pumps dont need the huge plumbing for good flow.

This relates to a question I asked in another thread, but I don't think I've got a reply yet... I'm thinking about going to an external pump to reduce heat going into water from the Mag12. I was looking at the head loss calculator and realized for the first time that I maybe only have 600 to 700 gph from my Mag12. So, I was thinking The MD55 RLT has similar gph to Mag12, but seems to have much higher max head. Would this pump give me greater flow rate with 0.75" plumbing at about 5' head compared to the Mag12? Also, do you think it would help my thermals? One last question do you think the MD70 RLT would be too much, notice that power consumption is about twice that of MD55. My sump is a SeaLife Systems SLS200 (probably a bad buy as I think it's a bit too small, maybe 15 to 20G), Tank is a 140G with twin overflow.

 

[JoeESSA]

I may be wrong, but wouldn't flow be only as strong as its weakest point. If so, when the return in reduced to 3/4 to fit the bulkhead it is only allowing the same amount of flow as if the whole return was 3/4?

No, total pressure drop over a length of piping will be greater the greater the length of the restricted portion. So, having 0.75" all the way will give greater pressure drop than 1" with a short 0.75" restriction.

 

[sjm817]

I've owned a Mag9.5, but not anything bigger. On that pump, 3/4" to 1.5" on ~ a 4' head made a HUGE difference. It was too much flow. I've seen others post similar exp with mag 12 and above.

I have no personal exp with the MD55/70, but I'm sure the flow difference would be dramatic.

The small 3/4" reduction at the bulkhead is not a big a flow restriction as running 3/4" the whole length. It has to do with friction loss in the plumbing. You have it just in a short section compared to the whole length.

All that being said, I dont like big return pumps. You need enough to supply the skimmer/fuge, etc, but no more. A return pump should not be a major source of display flow.

 

[JoeESSA]

I am actually thinking about a Mag12 for a return on a 190. The tank has two 1" drains with 24 linear inches of overflow and a 3/4 inch return bulkhead.

I think a Mag 12 sounds too small for a 190G. I have a Mag 12 on a 140G and I think the flow is too low. Guessing 600 to 700 Gph. At least I think this is maybe too little? I was figuring that I would be better off with 900 to 1200 Gph.

BTW, take a look at the "head loss calculator" on this site. I'm just starting to understand it, but I would guess that if you are mixing 0.75" sections with 1" sections you could put the average pipe diameter into the calculator to get a reasonable approximation. E.g. 2' at 0.75" and 3' at 1" your average would be (2x0.75+3x1)/5=0.9". Ahh,... calculator only accepts 0.75, 1, 1.5 etc...Oh well...

 

[JoeESSA]

So, where the flow/circulation comes from is down to personal choice perhaps within limitations of the setup. I find power heads kind of ugly although I do have a couple placed on the more hidden side of my tank.

I guess I just don't know if I actually need more than 600 to 700Gph for 140G reef with refugium, just going on a gut feeling that turning over more water would be "healthier" for the livestock. My main issue is actually temperature. Figuring that going to an external pump would help me with that?

 

[sjm817]

Rule of thumb is 3 - 5X display volume. 190G = 570 - 950GPH. 140G = 420 - 700GPH

You guys looking at Mag12s should consider an Eheim 1262.

 

[forensicdoc]

I have thought about the Eheim as well, but it is rated at 900 gph (665 gph at 4' head) compared to 1200 gph (1100 gph at 4') for the Mag12. Plus the Eheim has the issue of dealing with the non standard diameter (for the US) outlet fitting.

I have also read in threads that these numbers are not to be trusted, and that the Eheim actually pushes more water than the numbers show while the Mag pushes less. Can someone explain this inconsistency between provided and actual flow rates to me?

Thanks again!

 

[sjm817]

The Eheim will have similar or even better flow than the Mag12 when using 3/4" or 1" plumbing. The problem with the Mag is it is a flow pump. Without large dia plumbing, it is severly restricted. Eheim doesn't fall flat on its face under head pressure.

Yes, Eheim pumps flow more than they are rated for. One common theory is the ratings are for 50Hz. the faster impeller speed of 60 Hz increases flow by 20%. I dont know if this is actually the case.

For plumbing, a 3/4" MPT sched 80 fitting screws right in. It is VERY close in size to the metric threads. It goes in just a tad loose. nothing a few winds of Teflon tape wont fix.

You will also get a pump that is very quiet, energy efficient and reliablity is measured in decades.

 

[jdieck]

<a href=showthread.php?s=&postid=7439459#post7439459 target=_blank>Originally posted</a> by JoeESSA
A better way is to use a pump that handles head better than a Mag such as an Eheim or an external pump. These pumps dont need the huge plumbing for good flow.

This relates to a question I asked in another thread, but I don't think I've got a reply yet... I'm thinking about going to an external pump to reduce heat going into water from the Mag12. I was looking at the head loss calculator and realized for the first time that I maybe only have 600 to 700 gph from my Mag12. So, I was thinking The MD55 RLT has similar gph to Mag12, but seems to have much higher max head. Would this pump give me greater flow rate with 0.75" plumbing at about 5' head compared to the Mag12? Also, do you think it would help my thermals? One last question do you think the MD70 RLT would be too much, notice that power consumption is about twice that of MD55. My sump is a SeaLife Systems SLS200 (probably a bad buy as I think it's a bit too small, maybe 15 to 20G), Tank is a 140G with twin overflow.

At 5 feet head with 3/4" assuming a couple of elbows the Mag 12 will give you around 650 gph while the 55 RLT will give you close to 90
In both cases I would recommend a minimum return line of 1".
For that a Mag 12 will give you about 850 gph while the 55 RLT will give you 1000 gph.
If you move to the 70 RLT (1" dia return and 1-1/2" inlet minimum)
it will give you 1,300 gph which is not bad for a 140 g tank.

Just keep in mind that external pumps in general are noisier than internal pumps also high head pumps are also noisier than low head so you might not like it noise wise.

An unortodox alternative if you have room in the sump will be to add a second Mag 12 in series were the discharge of the first one feeds the inlet of the second pump, that combo will give you about 1000 gph if you also change the pipe dia to 1"

 

[JoeESSA]

jdieck. Thanks for the reply. Many alternatives to consider.

 

[TimFountain]

<a href=showthread.php?s=&postid=7439756#post7439756 target=_blank>Originally posted</a> by sjm817
Rule of thumb is 3 - 5X display volume. 190G = 570 - 950GPH. 140G = 420 - 700GPH

You guys looking at Mag12s should consider an Eheim 1262.

Agreed, and the Mag-12 is a real power hog/heater....