Before You Ask for a Tank Size, Count the Kilograms of Seafood
For a restaurant saltwater holding tank, choose the tank and sump from the maximum live seafood biomass, species, holding temperature, feeding policy, and expected holding time—not from the length of the restaurant wall. A 1,000-liter display holding a modest load of marine fish is a very different filtration problem from the same 1,000 liters packed with lobster or crab before a weekend dinner rush.
For a typical restaurant project, I would usually rather buy more water volume, more biological filtration, easier solids removal, independent aeration, and cooling redundancy than spend the same budget on decorative glass or excessive pump flow.
FAO guidance for recirculating aquaculture systems makes the engineering principle clear: complex recirculating systems require mechanical treatment, biological filtration and re-aeration, while the biofilter must provide enough surface for nitrifying bacteria to process ammonia generated by the livestock.
For a restaurant owner, there is an easier translation:
The glass sells the seafood. The life-support system keeps it sellable.
“I Have a 2-Meter Wall” Is Not Enough Information
This is where I would stop the quotation for five minutes.
Suppose a restaurant asks Ruibit for:
“A 2-meter-long saltwater seafood tank with sump.”
Fine.
How many kilograms of livestock?
Lobster, crab, marine fish—or all three?
Will they share water?
What temperature?
How many days between delivery and sale?
Will the seafood be fed?
What is the largest delivery before Christmas, Lunar New Year, or a weekend banquet?
Those answers can change the filtration system without changing the glass dimensions by one millimeter.
Research on live food-fish holding illustrates why biomass matters. In one small recirculating-system study, TAN accumulation was estimated at 35.6 mg per kg of fish per day for channel catfish and 21.6 mg/kg/day for largemouth bass; higher-density holding also produced higher TAN and unionized ammonia. Those exact values should not be copied onto marine restaurant species, but they demonstrate the correct design logic: waste follows biomass and biology, not tank labels.
How Much Tank Volume Would I Buy?
There is no responsible universal rule such as “10 liters per lobster.”
Species size, oxygen consumption, temperature, aggression, stacking behavior and water-treatment capacity all matter.
For preliminary restaurant planning, however, I would think in system classes:
| Restaurant Requirement | Practical Starting Direction |
|---|---|
| Small rotating display, modest stock | 500–800 L total display volume |
| Typical restaurant live-seafood display | 800–1,500 L |
| High-turnover restaurant / several species | 1,500–3,000 L+ , often divided into zones |
| Supermarket / seafood market / heavy holding | Engineer from kg biomass + species + daily throughput , not a generic liter figure |
These are planning ranges, not stocking-density guarantees .
A larger volume gives you something restaurant operators often undervalue: time.
If 10 liters evaporate or a small amount of waste enters a 300-liter system, the chemistry moves proportionally more than in a 1,500-liter system.
More water is not filtration.
But it is a useful buffer while filtration does its job.
One Big Tank Is Not Always Better Than Three Smaller Zones
This is where restaurant design and aquarium hobby advice part company.
Suppose you sell lobster, crab and marine fish.
Putting everything onto one common water loop looks cheaper.
It may also force animals with different temperature, behavior and husbandry requirements into one compromise system.
I often prefer separate hydraulic zones where species requirements justify them.
That can mean three display sections with independent treatment loops, or carefully designed groups sharing compatible water conditions.
The benefit is not only husbandry.
If one section develops a disease problem, contamination event or equipment fault, isolation becomes possible.
For a commercial Ruibit project, I would decide the hydraulic zoning before finalizing the cabinet layout.
The plumbing drawing should follow the seafood menu.
Not the other way around.
The Sump Should Start With the Dirty Stuff
For restaurant holding, mechanical filtration is not decorative.
It protects everything downstream.
The first stage should remove feces, shell debris, uneaten food and suspended solids before they accumulate inside biological media.
FAO's RAS guidance separates mechanical, biological and chemical filtration and also identifies settling and suspended-solids removal as core treatment functions.
For a restaurant sump, my preferred logic is:
Tank → coarse mechanical removal → finer mechanical stage where needed → biological media → additional treatment/aeration → return
Make the first dirty stage easy to remove and wash.
Seriously.
If cleaning requires tools, wet sleeves and forty minutes on the floor behind the restaurant bar, staff will postpone it.
A filter that is theoretically excellent but rarely cleaned is badly designed for hospitality.
Biological Media Is the Part I Would Not Undersize
The biofilter processes dissolved nitrogen waste.
Ammonia produced through metabolism is oxidized to nitrite and then nitrate by nitrifying bacteria. FAO specifically notes that the biological filter must provide sufficient attachment surface for the bacterial population required to process the ammonia load.
And those bacteria consume oxygen.
FAO gives approximately 4.0–4.6 units of oxygen consumption for each unit of NH₃-N oxidized to nitrate-N in the referenced recirculation design treatment.
That is why I dislike a restaurant quotation containing:
“Bio balls included.”
How many liters?
What media?
How is water distributed through it?
Is it submerged or aerated?
What biomass/feed load was used for sizing?
Can the media be serviced without destroying the bacterial colony?
Those are purchasing questions.
The Return Pump Is Not the Oxygen System
A large return pump moves water.
Good.
It does not automatically guarantee adequate dissolved oxygen.
High-density recirculating systems need deliberate oxygen management. UF/IFAS guidance for intensive RAS notes 5 mg/L dissolved oxygen as an important lower reference point in the discussed application, with supplemental aeration required below it and continuous aeration needed at high stocking densities.
For a restaurant holding system, I would specify:
return circulation
plus
dedicated aeration
and, for high-value/high-density applications, consider whether oxygen monitoring or additional oxygen capacity is justified.
If the main return pump fails during Saturday dinner service, I still want the livestock breathing.
That is why separate air supply can be cheap insurance.
Saltwater Restaurant Tanks Usually Need Serious Cooling
This is where the project cost can jump.
A restaurant is warm.
Kitchen equipment produces heat.
Lighting produces heat.
Pumps add heat.
People open doors.
And many live seafood species are held substantially cooler than the room.
So the chiller should not be selected from water volume alone.
The proper heat-load calculation should consider:
water volume
target water temperature
maximum room temperature
temperature pull-down requirement
pump heat
lighting
glass surface and insulation
livestock load
and how often new, warmer seawater or seafood enters the system.
For saltwater, the wetted heat exchanger also needs marine-compatible material. In Ruibit commercial seafood projects, this is the kind of specification I would want written explicitly rather than accepting “1 HP chiller included.”
Horsepower is a motor label.
Cooling capacity at the actual operating condition is the engineering number.
What I Would Put in the RFQ
If I owned the restaurant, my purchase request would look more like this:
Maximum live seafood biomass:
___ kg
Species:
___
Maximum holding duration:
___ days
Display volume:
___ L
Separate water zones required:
yes/no
Target temperature per zone:
___ °C
Mechanical filtration:
removable, high-load solids stage
Biological filtration:
media type + actual volume declared
Return pump:
delivered flow at real head, not zero-head rating
Aeration:
independent air system
Chiller:
cooling capacity declared at design conditions
Saltwater heat exchanger:
corrosion-resistant specification
UV:
function and design flow stated if included
Sump reserve:
verified by pump-off drain-back test
Drainage:
service drain and easy water-change arrangement
Monitoring:
temperature, salinity, pH, ammonia and nitrite
Emergency design:
power-loss and pump-failure plan
Maintenance access:
daily-cleaning components reachable in minutes
I also searched the Ruibit Alibaba storefront supplied for this article. I could not verify enough publicly indexed model-level specifications to responsibly quote a current Ruibit seafood-tank SKU, sump volume or chiller capacity, so those numbers should be established from the actual project drawing and livestock schedule rather than invented for a blog article.
Buy for Friday Night, Not Tuesday Afternoon
This is the restaurant rule I would keep.
Do not size the tank around the quietest day.
Size it around the largest realistic seafood delivery, the warmest restaurant conditions and the night when every table is occupied.
If the normal stock is 25 kg but Friday deliveries can temporarily put 50 kg into the system, tell the manufacturer 50 kg .
The filtration plant needs to know about Friday.
So does the chiller.
So does the oxygen system.
A restaurant saltwater tank is not really an aquarium with a sump underneath it.
It is a small recirculating life-support plant with glass on the front.
Choose the glass for the restaurant. Choose everything behind it for the seafood.
