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Why is there a common trend to grossly oversize return pumps on a new build.

LRT

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Bigger return for longevity of pump.
Upgrades.
Bigger backflow with gate valves for more control fine tuning flow.
Upgrades.
I've managed to achieve 4x turnover through my entire system and seems to be working well now.
Keep the surface moving and everything back to skimmer is what I try to accomplish.
 
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ca1ore

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Or 1/4th even. I have 2 x 2000gph pumps on a 400 gallon system but I measured my flow using the bucket/stopwatch method. I am getting 1000ghph.
That is with a head height of only about 2 feet too.
Yup .... I run a Vectra M1 on a closed loop and it works fine. Tried it on my return with back pressure and it was pathetic.
 

billwill

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Number one reason? Mostly because it's men, and that's how men's brains think. But the old rule is based on the days of your return pump providing most of the flow in the tank. It is grossly outdated, unless you're not going to be using any sort of power head in the tank. It also explains why there are so many negative reviews about external overflows. People buy these big pumps that can do 1800 gpm at 5' of head and expect an overflow rated at 1800 gpm to run silent with it.
 

WallyB

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Here is my thought.
Oversized Return pumps are kind of OLD School going back to the Early years of Reefing.

Back then, Return pump selection was oversized since there were no Variable Speed DC Pump Available, and the other MAIN REASON is selection of IN-TANK Powerheads wasn't what we have today.

The Power Heads (Back then) like the OLD MONSTER Tunzie that I still have were eye sores (In your tank).
Or Folks like myself would user Return Pump Flow Thru a Sea Swirl.

So a Larger Return Pump was needed to add in Tank Spray Bars, and extra outputs to generate in-tank Flow (and have things neat and tidy)
Thus the mentality was more than 2x Tank Sizes flow. (To account for Total flow in Tank)
AND I THINK some of that FLOW RATE mentality stuck on the X times number.

Now days with minature, powerful and cost Effective In-Tank Power Heads, we don't need the Extra Flow from a Return Pump (unless we want a DC Pump for the Future Larger Tank).

Another reason to bump up your Return Pump a bit, is if you want to use Return Flow for something like a VCA Random FLow Generator Nozzle. (WHICH isn't OLD SCHOOL DAYS STUFF)

(I actually use A VCA NOZZLE on on my Sea Swirl, and it's amazing)...
This test I did shows a comparision of Nozzles (Using Return Pump Power) and (also with In Tank Powerheads)


IN the Video above the Return Pump is running 2500Gph on a 110G Tank (25x).
Add in the Gyre and other pumps, the in tank flow is close to (100x).

This Next video show just the Return pump Running (25x) on the VCA Nozzle. (with the Random flow clearly seen)

So now days we have choices. Depends on your setup, and Higher flow requirements (for SPS corals).

If you don't use your Return Pump for Flow in your tank, or a future Larger Tank Option....Personally I think it a waste of money on the Pump, the Electricity to run it, etc.
 
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WVNed

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But I managed to cobble together something from my grossly overrated pumps and grossly overrated overflow
Into something that works and is quiet.
I really feel for the new people that don't have enough experience to make educated guesses when setting up new tanks.
This endeavor can slam the door in your face so hard it breaks your nose. You just have to get up and try again.
 

Silent

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First-time reefer here. In fact, I haven't even finished my build. Another fact, I don't even have a fish tank yet. But I jumped right in with 3 Iwakis for my first build!

(pic is WIP)

IMG_20200813_230820.jpg
Awesome you incorporated 2 different uv units on separate dedicated lines. I assume 1 for pathogens and 1 for algae. Great job so far.
 
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Boxfish

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Durability and track record of the higher "flow" pumps may come into play. Also in some brand the pricing is not hugely different then one a 1/3rd the size.
Don't we always say to get bigger because we are never satisfied fish keepers?
 

MastaMind82

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I think it is because most people who run these "oversized" pumps understand that there is a huge discrepancy between the dream figures posted in flow charts and actual flow into the display tank.
I'd have to agree with this. For instance my pump is rated 1,050 gph so on my 55 that would be a turnover of 19x. In reality when calculating my head pressure I am right around 7 ft of head pressure using 3/4" piping. I run the pump at 60% giving me a turnover near 4x. So those advertised numbers on the return pumps look big until you do the math and figure out what it will truly do in your system.
 

thewalkingdad

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Awesome you incorporated 2 different uv units on separate dedicated lines. I assume 1 for pathogens and 1 for algae. Great job so far.
You are correct my silent friend. GHA almost scared me out of the freshwater planted aquarium hobby and nobody likes ich, so I went with two.
 

mav3rick478

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My reason was I'm going to run a manifold, spray bar and the Triton method and possibly have the pump for a future upgrade. I'm also kind of old school hence the spray bar but it's cheaper than a Gyre pump.
 

Straasha

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I have a 55 gallon with the Jebao DCP-3000 rated for 790 gph (3000 lph) at 3. 0M. I estimated with my UV Sterilizer (Vecton 600), three 90 degree elbows, a VCA Random Flow Generator, and 2.5 feet of height using 3/4 inch pipe, I had about 6 feet (2 meters) of head pressure. Estimating about 1000 lph drop per 1 meter of head pressure, this would have given me about 260 gph (1000 lph) at 100% power. After I hooked everything up and timed how long it took to fill 2 gallons in a bucket, I had to dial it back to 50% in order to get around 250 gph (my target for about 5x turnover). So, in my case I bought the large pump based upon an estimate but didn't need the full capacity.
20200726_172455.jpg
 
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Palegic

Palegic

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I have a 55 gallon with the Jebao DCP-3000 rated for 790 gph (3000 lph) at 3. 0M. I estimated with my UV Sterilizer (Vecton 600), three 90 degree elbows, a VCA Random Flow Generator, and 2.5 feet of height using 3/4 inch pipe, I had about 6 feet (2 meters) of head pressure. Estimating about 1000 lph drop per 1 meter of head pressure, this would have given me about 260 gph (1000 lph) at 100% power. After I hooked everything up and timed how long it took to fill 2 gallons in a bucket, I had to dial it back to 50% in order to get around 250 gph (my target for about 5x turnover). So, in my case I bought the large pump based upon an estimate but didn't need the full capacity.
20200726_172455.jpg
I wouldn't consider a 790GPH a large pump at all for your setup. I similarly sized my pump conservatively for my tank (which is 54g with an 11g sump). Targeting 2x return flow.
 

PhreeByrd

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I think there are some misconceptions at work here. First of all, most reefers are not mechanical engineers and don't really understand pump specs. A pump almost never flows its full stated capacity, so pumps always need to be somewhat oversized. Manufacturers also love to inflate their flow specifications, and almost always model their pumps at 0' of head (resistance), which is not the flow rate any of us will ever see. The specs are not necessarily misstated, but they also do not reflect the real world. It's the responsibility of the user/engineer to check the pump's flow specs and curves and calculate what the real flow will be in their application.

People conflate pump/return flow with internal flow. Internal flow is not turnover. It's just circulation.

Assuming that your sump's main purpose is filtration (which is true for almost all of us running a sump), then high flow through the sump is not beneficial. For example, if your skimmer is in the sump (or connected to the sump as its water feed source), then ideally, it would process all the water entering the sump before the water gets past it. That means that flow through the sump should not exceed the skimmer's own pump flow rate. If you have biological filtration in your sump (sand bed, live rock, etc.), then the water also needs some dwell time in that media. How much is open to debate, however.

I looked at a couple of not inexpensive, variable flow DC pumps. The only specs I saw for flow rate were the manufacturers' stated maximum flow. That's an almost entirely useless figure. I emailed the manufacturers to ask for the flow curves, because they weren't published anywhere that I could find. What I received from both was a minimalist chart showing pump settings (flow %) and corresponding flow rates. Again, almost entirely useless.
 

Straasha

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In my example, for the Jebao DCP-3000 using a straight line graph with 3000 l/h at 0 meters to 0 l/h at 3 meters, I should have gotten 1000 l/h at 2 meters. The Jebao DCP-3000 out performed that; I had to cut it down to 50% in order to get 1000 l/h. In short, for a cheap pump, it performs pretty good.
 
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