Tank Turnover?

[bdare]

Hey all,

Looking to get back into the hobby after about 7 years off. I'm currently in the planning phases of a new tank which will be at least 150 gallons.

One thing I've decided on this tank is I don't want the top to bottom overflow box. I'm looking at some of the customer options from places like modular marine and shadow etc.

To make sure I size the box correctly I'm trying to figure out how much turnover I need in the tank? I've heard lots of arguments over the years about 10X and low flow sumps etc. Is 10X still the gold standard?

For a 150 gallon tank I need 1500gph flowing through my sump? Seems like a lot and could be noisy?

I guess as a follow up question... assuming I would want to build a manifold from my return to feed reactors... how big of a return pump do I need to get? Would a varios 8 running 2700gph be enough considering head loss etc?

Thanks in advance,
Ben

 

[Subsea]

Depending on what is going in the tank, 10 volumes of circulation in display tank is inadequate. High energy SPS display will have 30-50 volumes per hour. That means display tank circulation should be independent of sump circulation rate. With that said, the sump flow is dependent on the purpose for the sump.

I have skimmerless & sumpless tanks that are 10 years old.

In my 120G display with 40G cryptic refugium ((sump), I flow 200GPH.

https://www.reef2reef.com/threads/wet-salty-for-christmas-2017.428100/

 

[dugthefish]

5-10x through sump still seems to be the standard, augmented by in-tank circulation as needed for desired fauna. Running about 1200 in my 125. Fwiw, check into Exotic Marine Systems overflow box, I love mine.

 

[bdare]

Ah. Sorry for the confusion folks. I'm not at all referring to in tank flow for coral movement etc. I'm simply referring to flow from the tank through the sump for filtration purposes.

 

[WVNed]

I always heard 5-10 times so I use 6 when I design a system and buy pumps rated 6 times tank volume at the head I intend to run. I think if you want the overflow to be quiet oversize it a bit. It is easier to tune things when they aren't running at max capacity.

 

[sghera64]

In-tank water movement (recirculation) is more important than sump flow through in my opinion. Flow past the coral tissue is a primary transport mode. As the other person noted, I’d say 20 to 60x turnover within the tank is common. BRS was even planning/ considering up to 100x.

The processes that happen in the sump take place so “slow” (refugium, calcium reactor, skimmer) that getting 10x or fewer tank volumes passed through it is not a problem. When I say “slower” I mean the amount of a concentration difference that macro algae, CaRx, or skimmer can affect in a given amount of time is so small, that the difference in concentration between what is in the sump and what is in the tank does not need more than 10x pass-through.

I would recommend putting money ‘in’ the tank instead of beneath it. There are a bunch of in-tank power head recirc water threads on R2R arguing about best choice for the money. There are some good AC choices (Rosemont), and tons of DC choices ranging from practically disposable (Jebao’s) to mid-priced with great flow (Nero5) to lots of bells and whistles. I went with Jebao’s and have had good luck (for now - I’m told). Besides volume turnover, it matters how you use it. Random and turbulent flow are important to help SPS with gas and chemical exchange and so to with the live rock. I suppose the same is true to a lesser extent with the more ‘fleshy’ species in the tank (zoas, palys, LPS, anemones, clams).

 

[ca1ore]

I typically aim for 3-5x display volume through the sump per hour. I’ve neither read nor heard any cogent arguments for higher than that. Assuming heating/cooling is in the sump, you want enough turnover to maintain even temperature across the system and effect good surface skimming. Currently I run 1600 GPH through a modular marine overflow on about 400 gallons of display water.

 

[sghera64]

One more point, I have about 180 gal in my system and my Iwaki 30 struggles to deliver 400GPH (2.2 tank turnovers). I have no problem maintaining tank temp, pH and nutrient levels.

 

[bdare]

What about triton that says 10x is the standard?

 

[naterealbig]

Like @Subsea mentioned, it depends on how you are using it. 10x is definitely the high end, and that is what I am using - for now. My display is relatively new, and does not have a ton of corals, so I want to get any uneaten food, silt, and algae scrapings into the filter sock where I can remove it immediately. This works very well for the time being.

As I add corals, and a large biomass develops that utilizes the uneaten food and detritus, I will reduce my sump flow over time to around 2-3x turnover, where food dwell-time is maximized for the nutritional needs of mature animal colonies. I will be relying mainly on the refugium and skimmer to remove any excess organics at this point - neither of which require a large amount of flow.

If you are subscribing to a method such as Triton, then do what Triton tells you to do - or - don't expect the same results.

 

[bdare]

Thanks for all the opinions. I've been out of the game for awhile so I'm just trying to get caught up on recent trends / opinions. I've attached a pic from my old 120. I can always fall back to what used to work... but at I get back into the game I like to do my research. Thanks again for chiming in!!

 

[sghera64]

What about triton that says 10x is the standard?

I wondered why they said this too. I doubt they have data to show a significant difference between 2x pass through and 10x pass through. I recall Ryan at BRS saying he did not believe that 10x pass through was needed.

It just does not make sense. Me shooting 1800 (10 x 180) gallons of water per hour (30 gallons/ minute) through 15 gallons chaeto can’t be that superior to passing 6 gallons per minute. I mean, how fast does chaeto eat up nutrients from the water?

If I put 15 gallons of chaeto in a 20 gallon tank with 20 ppm NO3 and it also had good water movement, how long would it take that chaeto to knock the NO3 level down to 10 PPM? My guess is it would take more 3-4 minutes. Probably a lot more.

That’s my logic for why I don’t need to push more that 6 gallons per minute through my 20 gallon refugium holding 15 gallons of chaeto. These bio processes just run a lot slower than the tank turn overs we are able to achieve. I guess just because we can turn it over at 10x does not mean we must.

 

[19frank90]

Reviving an old thread. When determining turnover rate (whether for display/sump or in-tank circulation), each turnover rate is exclusive of the other correct? For example, I have a Red Sea 425 (88 gallon display, 24 gallon sump, 112 gallons total). My return pump is pumping 500gph, which is about 4.5x total system volume. My two MP40s are pumping about 2300gph (so 4600gph total).

If I were to then express the two turnover rates, I’d express them as follows, I think:
Display/sump - 4.5x (@500gph)
Display circulation - 4600 (52x, 4600/88)

Is that correct? Or does the 500gph get included in the in tank circulation? Then it’s 60x

Edit: Just saw that Red Sea recommends 1060gph for the return pump, which is 9.5x