Sump turnover rate on large tanks?

[ReeferBud]

How much is the ideal sump turnover rate and what is practical on large tanks?

I currently have a 450 gal tank and 120 gal sump and get 2000 gal/hr from a Reefflo Gold Hammerhead Hybrid. Tank is a mixed reef with a good amount of large SPS colonies and flow inside the display is provided by 4 Vortech MP40s and 2 Gyre XF350s, in addition to the returns.

The Reeflo feeds a manifold that has 2 canister filters for carbon/GFO, a UV filter and 2 3/4” returns to the display.

I recently got a nice deal on an Abyzz A200 and thinking of swapping out with the Reefflo. Looking at the pump curves, it looks like I would get less flow, perhaps around 1000 gal/hr. Would that be too low turnover?

thanks!

 

[ATB USA]

The general rule is 5 times to 10 times turnover for the aquarium. What you have now I would not go lower
So for a 450 you should have 2250 to 4500gph
1000gph would only be 2.2% turnover

 

[Smarkow]

I think that as you get to these larger tanks you need to think about what tank turnover and flow actually are doing for you, which is really just 3 things:

1) Homogenizing the water. Think of your sump as a water purifying station and your return pump as a water change for your display. That being said, it’s not efficient to have your sump completely purify the water once and then change it out to completely dirty water, most mechanical and biological filtration work better with continuous exposure to lower doses of impurities and longer contact time. So you need enough return flow to keep everything mixed and not stagnated.
2) Flow within sump. You want to optimize your flow for the filtration equipment housed within. Need to look at your manufacturer’s recommendations for this. Macroalgae typically grow better with more flow, but you can’t blast them either.
3) Return pump as a source of flow for the display and oxygenation for the water by breaking surface tension. This is where the real 10x per hour likely comes into play. It’s certainly true for smaller tanks. For bigger tanks with expensive return pumps it becomes a very cost inefficient way to generate flow compared to wave-makers, power-heads, and closed loops because return pumps almost always work against gravity.

So I’m not personally aware of any science that tells you exactly how much turnover you need or at what size this turnover could be acceptably lessened, but I do believe the 10x rule is more in tune with smaller tanks than larger ones.

 

[dwest]

1-3 turnovers through the sump is plenty IME. It looks like you will have great flow within the DT with your gyres and MP40’s.

 

[ReeferBud]

Thanks for the advice. I know this subject has been debated as long as the hobby’s been around and I do think that as tanks get larger, it becomes impractical to have the higher typical turnovers of 5x-10x that can be more easily achieved with smaller tanks.

Another option I have is to redo the plumbing so that the return pump ONLY returns water to the display, and have a separate pump for the UV filter and manifold with the canister filters. If I do this, I’ll probably get similar flow to what I have now with the Reeflo at 2000 gal/hr.

 

[AlexG]

I think the 10x/hr turn over is outdated from a time when flow was just coming from a return pump. As stated above once you get into larger systems its impractical to have that high of a turnover rate. I look at it as allowing more time for water to be filtered at a slower rate will likely do a better job than overwhelming the filtration system with max water flow that will likely allow some waste to pass through the system without having the time to be properly filtered. My last system was only turning over about 3-4x/hr and the skimmer was only turning over the tank volume ~1x/hr.

 

[Smarkow]

@ReeferBud

I think the 10x/hr turn over is outdated from a time when flow was just coming from a return pump. As stated above once you get into larger systems its impractical to have that high of a turnover rate. I look at it as allowing more time for water to be filtered at a slower rate will likely do a better job than overwhelming the filtration system with max water flow that will likely allow some waste to pass through the system without having the time to be properly filtered. My last system was only turning over about 3-4x/hr and the skimmer was only turning over the tank volume ~1x/hr.

It occurs to me (being a big fan of alex’s build) that his reef was very similar in size to yours. Alex is a plumbing genius, IMO

 

[Smarkow]

Thanks for the advice. I know this subject has been debated as long as the hobby’s been around and I do think that as tanks get larger, it becomes impractical to have the higher typical turnovers of 5x-10x that can be more easily achieved with smaller tanks.

Another option I have is to redo the plumbing so that the return pump ONLY returns water to the display, and have a separate pump for the UV filter and manifold with the canister filters. If I do this, I’ll probably get similar flow to what I have now with the Reeflo at 2000 gal/hr.

I think you will be happier with a manifold bc of the long term applicability of it as your filtration / equipment needs evolve.

The manifold pump can also be a backup pump if your return goes out, even if smaller it can often be enough to keep life support going. It can buy you a day or two to wait for your replacement to arrive. More cost effective than keeping a spare in storage where the seals and gaskets are aging/drying.

 

[Blue Tang Clan]

10x is completely unnecessary - you'd need water cannons

I think 1-3x is the most common, and you really need to have flow sensors to measure the real-world specs. I have two separate pumps into my display, each going through a UV around 600gph for a total of 1200gph.

 

[ReeferBud]

Thanks all!

I think some pretty common thoughts around the historical higher turnover rates being outdated in the time of good power heads, and impractical for large systems.

I’m going to explore the dual pump option (separate pump for manifold and UV), which would still likely get me in that 3x turnover range.

May come back for some plumbing advice, especially since we have a plumbing genius in our midst!

for reference, here’s a pic of the fish room and plumbing set up. What I’ll need to do is feed the manifold and UV from the 2nd pump.

 

[Smarkow]

Thanks all!

I think some pretty common thoughts around the historical higher turnover rates being outdated in the time of good power heads, and impractical for large systems.

I’m going to explore the dual pump option (separate pump for manifold and UV), which would still likely get me in that 3x turnover range.

May come back for some plumbing advice, especially since we have a plumbing genius in our midst!

for reference, here’s a pic of the fish room and plumbing set up. What I’ll need to do is feed the manifold and UV from the 2nd pump.

Nice fish room!

 

[KrisReef]

I am wondering what kind of flow and water change numbers large aquarium like the Monterey Bay Aquarium use in their systems? Just looking at the OP's pic I think there is adequate filtration and mineralization opportunities for a system 2-5 times of what is currently running?

I agree that flow in the tank is more important in the short term needs of a coral tank vs filtration and mineralization in the sump which is a (relatively) longer term issue when it comes to keeping a healthy tank.

Thanks for the pics!

 

[DaneGer21]

Although my tank isnt as large, only a 220 DT, but I use about a 2-3x turnover through my sump. But in tank is another story with 4-mp40s @ 90-95% reef crest.

 

[Blue Tang Clan]

Dual returns definitely help! Pic from my system below:

1. Keeps the overall flow rate high for the total system
2. Split returns keep each rate low (1/2 as much) for slower UV purposes to kill the nasties

 

[KStatefan]

Thanks all!

I think some pretty common thoughts around the historical higher turnover rates being outdated in the time of good power heads, and impractical for large systems.

I’m going to explore the dual pump option (separate pump for manifold and UV), which would still likely get me in that 3x turnover range.

May come back for some plumbing advice, especially since we have a plumbing genius in our midst!

for reference, here’s a pic of the fish room and plumbing set up. What I’ll need to do is feed the manifold and UV from the 2nd pump.

I think some of these high flow numbers you see people talk about have not been verified. Was watching a video the other day and they were talking about 2800 gph thru the sump but the water was barely moving in the sump.

 

[DaneGer21]

Although my tank isnt as large, only a 220 DT, but I use about a 2-3x turnover through my sump. But in tank is another story with 4-mp40s @ 90-95% reef crest.

I think some of these high flow numbers you see people talk about have not been verified. Was watching a video the other day and they were talking about 2800 gph thru the sump but the water was barely moving in the sump.

Fortunately for me I have installed flow sensors on each return side. I was surprised how low numbers actually are because of my plumbing..

But yes, I’m sure some assume they are WAY higher than they actually are!

 

[ReeferBud]

agreed! I also have a flow sensor on my return, which is why I know it’s 2000 gal/hr but if I just had to guesstimate the flow without the sensor, I probably would have estimated way higher based on the 6000 gph rating of the pump.

what would be a good pump for my UV and manifold? I would prefer it to be apex controllable, which rules out the Vectra, although interested in something similar and submersible.

 

[ReeferBud]

Dual returns definitely help! Pic from my system below:

1. Keeps the overall flow rate high for the total system
2. Split returns keep each rate low (1/2 as much) for slower UV purposes to kill the nasties

nice set up! Love the plumbing and filtration.

I see you have the same drip pans as I have under your UVs. One of the best things ever for placing reactors and filters. I’m surprised they’re not more common.

 

[Blue Tang Clan]

I got my drip pans from Chewy.com - cheap dog crate pans (not the exact name) that have so many uses in a fish room!

 

[ca1ore]

FWIW, I’m running a PanWorld 250 on my 450 and I get about 1,500-1,600 GPH. Most tanks hold less water than their advertised size, so in my case 400 net gallons means about 4x. Hard to see how that’s not enough. I do have significantly more in tank flow though - four MP60, one MP40, two RPM and a closed loop.