Free tool
Oxygen demand and sizing calculator
Turn a dissolved-oxygen deficit into the number that actually sizes equipment: kilograms of oxygen per hour.
Sizing a nanobubble system starts from an oxygen budget, not a tank volume. Multiply your loop flow by the dissolved-oxygen deficit you need to close and you get the mass of oxygen to transfer per hour; divide that by the concentration the generator delivers and you get the side-stream flow it has to handle. This calculator does both, and shows the working.
How to use this calculator
Enter the flow through your loop, where dissolved oxygen sits today and where it needs to be. The delivered-concentration selector reflects the three duty points NanoMAR publishes for the NanOxy Pro.
Inputs: flow, DO target, temperature
There are only two equations here, and both are definitions rather than assumptions. That is deliberate: a sizing tool you cannot check is a sales device, not an engineering aid.
Step one — the mass of oxygen. Concentration is mass per volume, so multiplying the flow through your loop by the concentration deficit gives the mass rate you have to transfer:
demand (kg O₂/h) = flow (m³/h) × deficit (mg/L) ÷ 1000
A hundred cubic metres an hour with a 3 mg/L deficit is 0.3 kg of oxygen per hour. This is the number that sizes equipment, and it is the number most enquiries do not arrive with.
Step two — the side-stream flow. A generator is specified by the concentration it delivers into a slipstream. Rearranging the same definition tells you how much water has to pass through it:
side-stream flow (m³/h) = demand (kg/h) × 1000 ÷ delivered concentration (mg/L)
Which is why the delivered concentration matters so much. The same duty needs four times the flow at 10 mg/L that it needs at 40 mg/L, and that ratio decides the size of everything downstream of the decision.
Why does the NanOxy Pro have three published flow rates?
NanoMAR publishes the NanOxy Pro at three flow rates. They are not three machines — they are the same oxygen mass rate expressed at three concentrations.
| Delivered concentration | Published flow | Oxygen transferred |
|---|---|---|
| 40 mg/L | 18.9 m³/h | 0.756 kg/h |
| 20 mg/L | 37.8 m³/h | 0.756 kg/h |
| 10 mg/L | 75.6 m³/h | 0.756 kg/h |
Multiply any row out and you get the same figure. That is the whole point: the machine transfers a fixed mass of oxygen per hour, and you choose whether to deliver it as a small flow at high concentration or a large flow at low concentration.
Assumptions and limits
Be honest with yourself about the gap between this figure and a specification. These are the things that move the answer, and none of them can be guessed from four inputs.
- Peak load, not average load. Design against the worst hour of the worst day. Feeding peaks, warm water and a full biofilter do not arrive politely spaced out.
- Temperature and salinity. Warm water and salt water both hold less oxygen at saturation, which changes the deficit you are actually closing and the driving force available.
- Losses in your own loop. Degassing at surfaces, stripping in a sump and the demand of the biofilter itself all sit between the generator and the fish.
- What else the water needs. If the duty is disinfection or biofilm control rather than oxygenation, the sizing question is an ozone dose question and this tool is the wrong one.
- Headroom for the process you will have. Stocking density rises and discharge limits tighten. Sizing exactly to today means replacing the unit rather than turning it up.
Want a detailed engineering calculation?
Once you have a defensible oxygen budget, the remaining decisions are about your site rather than about arithmetic: which gas, where the unit sits in the loop, and which separation stage suits the water. Those are covered in the generator guide, and because the same three decisions are what move the cost of the installation, a duty figure has to come before a quotation.
If the number you produced here surprises you — in either direction — that is worth a conversation on its own. A demand far below expectation usually means the deficit is smaller than assumed; far above usually means the flow figure is the whole circulation rather than the slipstream. Both are common, and both change the answer completely.
Send the four numbers you entered, plus your temperature and what the water is doing today, and our engineers in Bergen will work through the specification with you. What that process looks like is set out under pilots and validation.
Frequently asked questions
- What is oxygen transfer efficiency?
Oxygen transfer efficiency is the share of the oxygen you supply that actually ends up dissolved in the water rather than escaping to the atmosphere. It is the figure that decides running cost, and NanoMAR publishes a 40 %+ improvement in oxygen transfer for nanobubble systems compared with conventional bubble aeration.
- How do I calculate how much oxygen my system needs?
Multiply the flow through your loop in m³/h by the dissolved-oxygen deficit in mg/L and divide by 1000, which gives kilograms of oxygen per hour. The NanoMAR calculator on this page does that and then converts it into the side-stream flow a nanobubble generator has to handle.
- Why does the required flow change with delivered concentration?
Because the machine transfers a fixed mass of oxygen per hour. NanoMAR publishes the NanOxy Pro at 18.9 m³/h at 40 mg/L, 37.8 at 20 mg/L and 75.6 at 10 mg/L — all three are 0.756 kg of oxygen per hour, delivered as different combinations of flow and concentration.
- Can I use this result to request a quotation?
Yes, and it will make the conversation much faster. Send the figure along with your temperature, salinity and peak-load conditions, and NanoMAR can size a nanobubble system against real operating conditions rather than an average.
Check the number with an engineer
Send what you entered plus your temperature and peak conditions, and we will tell you honestly whether the figure holds up.
Ready to rethink your water?
Tell us about your process and we'll size a nanobubble system for it.
Talk to our team