Water quality is the foundation of a healthy aquarium. Without proper conditioning, tap water can introduce harmful chemicals that stress or even kill fish, invertebrates, and beneficial bacteria. That’s where Seachem Prime comes in—a concentrated, highly trusted water conditioner designed for both freshwater and marine aquariums.
In this guide, you’ll learn exactly what Seachem Prime does, how to use it safely, and why it’s one of the most versatile tools for both new and experienced aquarists.
What Is Seachem Prime?
Seachem Prime is a complete and concentrated water conditioner that removes chlorine and chloramine, detoxifies ammonia, nitrite, and heavy metals, and supports the biological filter. Unlike basic dechlorinators, Prime offers a multi-layered approach to water safety—making it ideal for tank cycling, routine water changes, and emergency situations involving ammonia or nitrite spikes.
Prime is safe for all aquatic life, including fish, invertebrates, corals, and live plants. It works instantly and is compatible with most water treatment systems and aquarium setups.
What Does Seachem Prime Do?
Seachem Prime performs several critical functions:
-
Neutralizes chlorine and chloramine from tap water instantly
-
Detoxifies ammonia and nitrite into non-toxic forms, which are still available for bacteria to consume
-
Binds heavy metals such as copper and zinc, protecting sensitive species
-
Supports the biological filter during tank cycling or bacterial disruption
-
Reduces stress during water changes and tank maintenance
Because of this broad functionality, Prime is more than a basic dechlorinator—it’s a protective buffer against a wide range of water quality threats.
When Should You Use Seachem Prime?
You should use Seachem Prime in the following scenarios:
-
During water changes to neutralize harmful chlorine and chloramine in tap water
-
When starting a new tank (cycling) to protect fish from ammonia and nitrite
-
After dosing ammonia detoxifiers or medications that disrupt the biofilter
-
If test kits show ammonia or nitrite spikes, either due to overfeeding, filter crashes, or new livestock
-
In tanks with high organic waste, especially heavily stocked systems or temporary holding tanks
How to Dose Seachem Prime
The standard dosage of Seachem Prime is 5 mL per 200 litres (50 US gallons) of water. For smaller tanks, dose 1 mL per 40 litres. You can use a syringe, dropper, or Seachem’s dosing cap for accurate measurement.
For Water Changes
Add Prime directly to the new tap water before introducing it into the tank. Alternatively, dose it straight into the aquarium just before the new water is added.
For Ammonia Detoxification
In emergencies, Prime can be safely dosed up to 5 times the standard amount. For example, you can add 25 mL per 200 litres in cases of toxic ammonia levels. This detoxifies ammonia and nitrite without removing them from the biofilter cycle.
For Cycling New Tanks
Dose daily for the first 7–10 days in conjunction with a bacterial additive like Seachem Stability. This provides fish with protection during the critical phase where beneficial bacteria have not fully established.
Compatibility and Safety Tips
-
Prime works well with most water conditioners, buffers, and supplements.
-
Avoid combining Prime with oxidisers like potassium permanganate or hydrogen peroxide, as they may cancel each other out.
-
Prime is safe for plants, shrimp, snails, and corals when used at the recommended dosage.
-
Always turn off UV sterilizers when using Prime during high-dose detoxification—UV can break down the chemical bonds that neutralize ammonia.
-
You can continue to use Prime even with salt mixes, provided it’s dosed before adding water to your salt mix or into the tank.
Can You Overdose Seachem Prime?
While Seachem Prime is concentrated, it has a wide safety margin. Overdosing slightly during emergencies is generally safe. However, repeated heavy overdoses may cause temporary changes in oxygen levels or cause some protein skimmers to behave erratically in marine tanks. Stick to recommended doses unless managing a specific water chemistry issue.
How to Tell If Seachem Prime Is Working
Prime works instantly but does not remove ammonia—it binds it in a non-toxic form that still shows up on most API-style ammonia test kits. This can lead to confusion, as the ammonia level might appear unchanged. Use Seachem’s Ammonia Alert or MultiTest kits, which differentiate between free (toxic) and bound (non-toxic) ammonia.
You’ll also know Prime is working if:
-
Fish are no longer gasping or stressed after a water change
-
Ammonia or nitrite toxicity symptoms decrease after dosing
-
Beneficial bacteria continue to cycle the tank normally
Storing and Using Prime Long-Term
Store Seachem Prime in a cool, dry place away from direct sunlight. The product does not require refrigeration. It has a long shelf life and does not degrade quickly unless exposed to air for prolonged periods. Keep the cap tightly closed between uses.
Prime is available in multiple sizes, from 100 mL to 4 L bulk containers, making it cost-effective for long-term use and large-volume systems.
Final Thoughts: Why Seachem Prime is an Essential Aquarium Staple
Seachem Prime is more than a dechlorinator—it’s a comprehensive water treatment solution that helps you manage sudden spikes in toxins, protect your livestock during water changes, and stabilize new setups with minimal stress.
Its high concentration, proven safety, and ability to detoxify ammonia and nitrite make it a standout product for all levels of aquarists. Whether you’re maintaining a peaceful freshwater tank, a shrimp colony, or a bustling reef, Prime is a go-to product that no fishkeeper should be without.
