Pack size
500 mL
Cost per litre
Under 1c
Water type
Marine + Reef
Continuum ULNS Nitro Nitrogen Supplement 500ml
Continuum ULNS Nitro restores nitrogen to reef tanks that have been stripped too clean. It's a complex inorganic nitrogen source built for ultra-low-nutrient systems (ULNS) where nitrate has bottomed out – the point where corals start to pale, bleach or lose tissue because the bacteria and zooxanthellae they depend on are starving. Dosing is calculated from your measured nitrate reading rather than applied on a fixed schedule, so testing before every dose isn't optional.
Key features
- Targeted nitrogen source – for reef systems where nitrate has fallen below Continuum's recommended range.
- Dose calculated from your test result – not a flat daily dose; you measure, then dose to the number.
- Pairs with bacterial dosing – Continuum recommends using it alongside BacterGen•M or Reef Micro•Fuel for bacterial support.
- Advanced hobbyist product – intended for reefers already running a ULNS system and comfortable testing regularly.
- Under 1c per litre – at Continuum's reference dosing rate, the 500 mL bottle works out to under 1c per litre of tank water treated.
Specifications
| Specification | Detail |
|---|---|
| Type | Complex inorganic nitrogen supplement for nitrate-limited reef systems |
| Active constituents | Continuum describes this as a complex inorganic nitrogen source (nitrogen salts); a full ingredient breakdown is not published |
| Target nitrate range | 3.0–5.0 ppm |
| Pack size | 500 mL |
| Suitability | Marine and reef aquaria running ultra-low-nutrient systems |
| Cost per litre | 500 mL: under 1c per litre, based on Continuum's reference dose of 5 mL per 100 L |
Dosage and directions
How much do I dose?
5 mL raises nitrate by approximately 0.5 ppm in 100 L (25 US gallons). For other volumes, Continuum's formula is: tank volume in US gallons × desired ppm increase × 0.4 = millilitres to dose. As an example, a 100-US-gallon tank needing a 0.5 ppm rise takes about 20 mL, or roughly 4 capfuls.
Before you dose
Test nitrate and phosphate first. Only dose if nitrate is below 3.0 ppm – Continuum's target range for a ULNS system is 3.0 to 5.0 ppm. Shake the bottle well, dose, then wait 24 hours before retesting.
What to pair it with
Continuum recommends dosing alongside BacterGen•M or Reef Micro•Fuel for bacterial support, and pairing with Continuum ULNS Phos if phosphate is also undetectable.
Suitable for, and not suitable for
- Suitable for: established reef systems running ultra-low-nutrient husbandry where nitrate has dropped below 3.0 ppm and corals are showing signs of nutrient starvation.
- Not suitable for: tanks that are not nitrate-limited – dosing nitrogen into a system that doesn't need it will push nutrients up and can trigger nuisance algae.
Safety
Overuse can promote nuisance algae, so dose to a tested figure rather than guessing. Keep out of reach of children; not for human consumption. Contains nitrogen salts – if the product contacts eyes, flush with water.
Warranty and delivery
Sold with Continuum's standard packaging warranty against manufacturing defects, in addition to the consumer guarantees you're entitled to under Australian Consumer Law. Ships from Nick's Aquarium Oceanarium Terrarium in Brisbane / North Lakes, QLD.
Common questions
How do I know if I need this?
If your reef tank's nitrate has dropped below Continuum's recommended 3.0–5.0 ppm range and corals are paling, bleaching or losing tissue, ULNS Nitro is designed to bring nitrate back into range.
How often can I dose?
Continuum's process is test, dose, then wait 24 hours before retesting – there's no fixed daily schedule. Dose again once you've confirmed where nitrate sits.
Can I use this to lower nitrate?
No. ULNS Nitro adds nitrogen – it raises nitrate, it doesn't lower it.
What else should I be dosing alongside it?
Continuum recommends BacterGen•M or Reef Micro•Fuel for bacterial support, and its companion product ULNS Phos if phosphate is also undetectable.




