Is lifereef really the best skimmer?

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francesco.mancini

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DCR

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The focus on pump capacity is misguided. According to the Mazzei performance tables, the 978 injector needs 5 psig or 11.5 ft of head to pass even 246 gph. The required head doubles (23 ft) to pass 342 gph, so the water flow is very low on these skimmers. You need adequate head to get the right air draw. I recall from the RC thread where someone tested the air flow and the optimum was about 20-24 SCFH with 12-15 ft of head. More than that and it flooded the 6" chamber with air unless you throttled the air rate down. It sounds like some people are still getting acceptable results with lower head pressures like 10-11 feet, but their air flow will be reduced. Whether the pump is AC or DC does not matter as long as it delivers adequate head at the 250 gph that will be fed to skimmer.

The Mazzei data suggest the air draw would only be 18 SCFH at 11.5 ft of head with no back pressure, but this likely includes the standard spring loaded check valve in the air port. I think everyone removes this which should improve the air rate.
 

Water Dog

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I’ve been part of that RC thread for quite some time. i remember the Dwyer airflow meter tests specifically as I had a Fluval SP4 on my 24” skimmer at the time and somebody put up the airflow numbers for the SP4 on both the 24 and 30 inch skimmers. IIRC, wasn’t it mentioned on that thread that Jeff used a Mag 12 or 18 on his 24 incher?
 

DCR

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I’ve been part of that RC thread for quite some time. i remember the Dwyer airflow meter tests specifically as I had a Fluval SP4 on my 24” skimmer at the time and somebody put up the airflow numbers for the SP4 on both the 24 and 30 inch skimmers. IIRC, wasn’t it mentioned on that thread that Jeff used a Mag 12 or 18 on his 24 incher?
I thought most people were using Mag 12's on the 24" which would put up about 11.8 ft of head at 250 gph. The recommended Mag 9.5 is only few inches less than the Mag 12. He does recommend the Mag 18 for the 30 and 36" models which will put up about 15.8 ft of head. You do need more head with the taller skimmers to overcome the backpressure on the backside of the injector.
 
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TaylorPilot

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Interesting, so why doe sthe AC pump pull so much more power? Is it actually more powerful? I am confused because he says the pump needs to be 600gph but told me a jebao 4500 (1056 gph) is not strong enough but his Mag drive (1010gph) is. I dont understand.
A 24-36v DC motors (kind used in this hobby) by themselves will never more more efficient than a 120V AC motor. Think about it. They take 120v power and have to step it down to 24/36v, as well as power the electronics to drive the motor. That stepdown always creates heat, which is wasted electricity. In fact, that is the reason most DC pump controllers fail. They are undersized without adequate heat sinks, so they get hot and fail prematurely. The difference comes in the fact that the DC pumps are typically designed to be high volume/low pressure pumps. Most of your Iwaki/Panworld or Sicce pumps are higher RPM with smaller impeller housings and smaller output sizes. They usually handle head pressure better, making them better for this application. Where DC pumps do outpace AC pumps is in the noise department. The controllers are able to smooth out the impulses. I wouldn't be too worried about pump power consumption in this range of application. Reason being that in a submersible pump, 99.9% of the electricity sent to the pump is converted to heat inside the water. So unless you run into heat problems and don't run heaters, any excess power consumed by the higher pressure pump, will be offset by running your heater less. Also, when you choke down the water flow at the injector, it actually lowers the power consumption. You would think it is opposite, but it isn't. Take a AC pump and put a valve on the outlet. As you restrict the flow on the outlet, the power consumption will go down. My advice is that if you can find an AC pump that you are comfortable with the noise level, use it. They will always be more reliable than their DC counterparts and in most cases, won't cost you a dime of electrical cost. IMHO
 

Jerry Barnes

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I'm not sure about all this pump talk but I can tell you that I've been using LIfereef skimmers for 30 years. My oldest one is 15 years old and is still running the same mag pump. The skimmer pump combination recommended by Jeff has always worked well for me and has been 100% reliable.
 

Water Dog

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All this back and forth pump talk is simply because people are searching for comparable alternatives in performance to the venerable Danner Mag Drives that are less noisy and less thirsty in terms of energy consumption. There’s no question that Mag Drives are ultra reliable and bombproof. I still have a 15 year old Mag 12 that still works like the day it was first plugged in! :)
 

dragon99

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I feel like this sums up the AC vs DC debate pretty well, ECM or brushless DC are what we see in the hobby:

"For a given amount of mechanical work output, AC motors are usually larger than DC motors, with brushless DC designs being the smallest. AC motors have a long service life while DC motors require more maintenance for those designs that use brushes and commutators which feature mechanical wear. Electronically Commutated Motors (ECMs) are a form of brushless DC motor that eliminates mechanical commutation and brushes in favor of electronic commutation and control, therefore improving useful life, reducing power consumption, running cooler, and providing better performance."

AC pumps aren't bad, they run forever, but they are terribly inefficient which makes them giant block heaters in a tank. For some people that's a bonus.
 
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piranhaman00

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DCP-6500 on 30
Unfortunately I have to sell my 30 as it don’t fit under my new Waterbox

That works well for that size? Seems like it would be undersized.

Can someone explain how the fluval pumps head is low compared to watts and flow rate? Is jebao just drastically over stated?


Jebao 8000 states 18ft at 65 watts 2100gph, I am struggling to understand which pumps are best with these skimmers. It would seem jebao dcp is a no brainer but people suggest ac pumps such as sicce and fluval.

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1612903331740.png
 

Reefvision

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I use mag 24 (per Jeff’s recommendation for this lifereef skimmer (42”totalheight) fed from sump opposite side of wall . Does well for 3years now.
 

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Blitzie

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I use mag 24 (per Jeff’s recommendation for this lifereef skimmer (42”totalheight) fed from sump opposite side of wall . Does well for 3years now.
When I first got mine I used a Mag 18 and I know people don't like them for one reason or another but They do work very well. I dropped mine while cleaning it on day and replaced it with the DCP-6500 because a local shop had it on the shelf
 

DCR

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That works well for that size? Seems like it would be undersized.

Can someone explain how the fluval pumps head is low compared to watts and flow rate? Is jebao just drastically over stated?


Jebao 8000 states 18ft at 65 watts 2100gph, I am struggling to understand which pumps are best with these skimmers. It would seem jebao dcp is a no brainer but people suggest ac pumps such as sicce and fluval.

1612903379699.png


1612903331740.png
The Jebao pumps can certainly work, but the developed head drops off very quickly as the flow increases. The actual head of the 6500 flowing 300 gph through a Mazzei is only going to be about 11.5 ft - very similar to the Fluval SP4. The AC pump curves hold the head much better as you start increasing the flow.

Another thing to note is that the power consumption of an AC pump is reduced at reduced flow rates. The SP4 is likely to draw more like 55-65 W in the 250-300 gph Mazzei application. The same is not true of the DC pump. It will draw full power across the flow band at maximum speed.

Also I believe that Jebao power ratings are not at the wall outlet. They exclude the power losses in the converter. I recall one of the German made pump reps pointing this out on an old RC thread.

Bottom line is the power consumption difference may not be as large as it seems.
 

piranhaman00

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Does anyone use hard pvc plumbing for their skimmer? Jeff recommends tubing but I do not trust tubing to hold under pressure. I know it will but I feel safer with pvc glue.
 
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