Best Aquarium Water Conditioners (2026): Complete Buyer's Guide
Water conditioner is the most essential product in fishkeeping. We compare the top dechlorinators so you can choose the right one for your tank.
Quick Pick: Best Overall
Seachem Prime - The industry standard. Treats 2,500 gallons per 250mL bottle, neutralizes chlorine/chloramine/ammonia/nitrite. Best value for money.
Check Current Price on Amazon →Why You Need a Water Conditioner
If you use tap water for your aquarium, you must use a water conditioner. Here's why:
Chlorine and chloramine in tap water will kill your fish. These chemicals are added by water treatment plants to make water safe for humans - but they're toxic to fish gills and kill beneficial bacteria in your filter.
What Water Conditioners Do:
- Neutralize chlorine - Instantly binds chlorine into harmless compounds
- Neutralize chloramine - Breaks the chlorine-ammonia bond (important: chlorine alone doesn't handle this)
- Detoxify heavy metals - Binds copper, lead, zinc from old pipes
- Protect slime coat - Some formulas add aloe or protective colloids
- Detoxify ammonia/nitrite - Premium conditioners like Prime also handle these
Does Your City Use Chloramine?
Over 30% of US water systems now use chloramine instead of chlorine. Chloramine does NOT dissipate on its own - leaving water out overnight won't help. Check your city's water quality report or call your water utility to find out.
Water conditioner is used every time you:
- Perform a water change
- Set up a new tank
- Top off evaporated water with tap water
- Treat an ammonia spike
Quick Comparison: Top Water Conditioners
| Product | Best For | Treats (per bottle) | Key Feature | Price |
|---|---|---|---|---|
| Seachem Prime | Most aquariums | 5,000 gal (500mL) | Detoxifies ammonia/nitrite | $15-20 |
| API Stress Coat | Injured/stressed fish | 960 gal (16oz) | Aloe vera for slime coat | $10-15 |
| Fritz Complete | Budget-conscious | 4,800 gal (16oz) | Great value | $8-12 |
| Kordon NovAqua+ | Premium protection | 960 gal (16oz) | Full-spectrum protection | $12-16 |
| Tetra AquaSafe | Beginners | 1,000 gal (16.9oz) | Easy dosing, widely available | $8-12 |
*Prices are approximate and may vary. Use our Tank Volume Calculator to determine how much conditioner you need.
1. Seachem Prime - Best Overall Water Conditioner
Seachem Prime is the gold standard in the aquarium hobby. It's what fish stores use, what Reddit's r/Aquariums recommends, and what most experienced fishkeepers keep on hand. There's a reason it's been the #1 seller for decades.
What Makes Prime Special:
- Complete protection - Neutralizes chlorine, chloramine, AND detoxifies ammonia, nitrite, and nitrate
- Incredible concentration - 1 mL treats 10 gallons (just 2 drops per gallon)
- Emergency ammonia treatment - Can dose up to 5x normal during ammonia spikes
- Safe for all aquarium inhabitants - Fish, invertebrates, plants, corals
- Cost-effective - A 500mL bottle treats 5,000 gallons
Pros
- + Best value per gallon treated
- + Detoxifies ammonia/nitrite for 24-48 hours
- + Highly concentrated (less plastic waste)
- + Safe for all aquatic life
- + Indefinite shelf life
Cons
- - Strong sulfur smell (normal, not harmful)
- - Can interfere with ammonia test readings
- - Concentrated formula requires careful dosing
Dosing Guide for Seachem Prime:
- Normal use: 1 mL (1 capful = 5 mL) per 10 gallons
- Emergency ammonia: Up to 5 mL per 10 gallons
- New tank setup: 2 mL per 10 gallons
- Water changes: Treat the volume of new water added
Our Verdict: Seachem Prime is the best water conditioner for 90% of aquarists. The ammonia-detoxifying ability alone makes it worth the price, especially during the nitrogen cycle or emergencies.
Check Price on Amazon2. API Stress Coat - Best for Stressed or Injured Fish
API Stress Coat is unique because it contains aloe vera, which helps heal damaged fish skin and rebuild the protective slime coat. If you have fish recovering from illness, injuries, or the stress of transport, this is the conditioner to reach for.
When to Use Stress Coat:
- After adding new fish - Reduces transport stress
- Treating injuries - Fin damage, scrapes, ulcers
- After disease treatment - Helps rebuild slime coat damaged by medications
- Handling fish - Net burns, hand contact
- Tank moves - Relocating aquariums
Pros
- + Contains healing aloe vera
- + Replaces protective slime coat
- + Reduces fish stress
- + Handles chlorine and chloramine
- + Widely available at pet stores
Cons
- - Does NOT detoxify ammonia
- - Lower concentration than Prime
- - More expensive per gallon treated
- - Some reports of foaming
Our Verdict: Keep a bottle of Stress Coat alongside your regular conditioner (Prime). Use Stress Coat when fish are injured, stressed, or recovering from illness. Use Prime for everyday water changes.
Check Price on Amazon3. Fritz Complete - Best Budget Water Conditioner
Fritz Complete is the best-kept secret among fish stores and serious hobbyists. It does everything Seachem Prime does at a lower price point. Fritz has been making professional-grade aquarium products since 1984.
Why Fish Stores Love Fritz:
- Professional formula - Used by public aquariums and fish farms
- Complete protection - Chlorine, chloramine, ammonia, nitrite, nitrate
- Excellent concentration - 1 mL per 10 gallons
- No smell - Unlike Prime's sulfur odor
- Available in bulk - Up to 1 gallon sizes for serious hobbyists
Pros
- + Lower price than Prime
- + No unpleasant odor
- + Detoxifies ammonia/nitrite like Prime
- + Available in larger sizes
- + Trusted by professionals
Cons
- - Less widely available in stores
- - Less brand recognition than Prime
- - Some hobbyists report inconsistent results
Our Verdict: Fritz Complete is the smart choice for budget-conscious aquarists who don't want to sacrifice quality. If you maintain multiple tanks or do frequent water changes, the savings add up.
Check Price on Amazon4. Kordon NovAqua+ - Best Premium Water Conditioner
Kordon NovAqua+ is the premium choice for aquarists who want comprehensive protection. It's particularly popular among koi keepers and those with sensitive or expensive fish.
What Sets NovAqua+ Apart:
- Organic slime coat protectants - Superior coating compounds
- Heavy metal detoxification - More comprehensive than competitors
- pH buffering - Helps stabilize water chemistry
- Electrolyte balance - Adds essential minerals
- Vitamins - B vitamins for fish health
Pros
- + Most comprehensive formula available
- + Excellent for sensitive species
- + Adds beneficial electrolytes
- + Works great paired with AmQuel+
- + Trusted by koi hobbyists
Cons
- - Does NOT detoxify ammonia (need AmQuel+ separately)
- - More expensive per treatment
- - Overkill for basic freshwater tanks
Our Verdict: NovAqua+ is best for koi ponds, discus tanks, or when keeping expensive/sensitive fish. For most community tanks, Prime or Fritz Complete is sufficient and more cost-effective.
Check Price on Amazon5. Tetra AquaSafe - Best for Beginners
Tetra AquaSafe is the water conditioner most beginners encounter first. It's sold at every pet store, comes with clear instructions, and has been a reliable choice for decades.
Why Beginners Love AquaSafe:
- Simple dosing - Easy-to-read cap measurements
- Available everywhere - Walmart, PetSmart, Petco, etc.
- Affordable - Lower upfront cost than concentrated formulas
- Trusted brand - Tetra has been around since 1951
- Works with Tetra SafeStart - Good combo for new tank cycling
Pros
- + Easy to find in stores
- + Simple, beginner-friendly dosing
- + Contains colloids for slime coat
- + Affordable entry point
- + Handles chlorine and chloramine
Cons
- - Does NOT detoxify ammonia
- - Lower concentration (less economical long-term)
- - Contains artificial coloring
- - Not the best value per gallon
Our Verdict: AquaSafe is a fine starter conditioner, but most hobbyists upgrade to Seachem Prime or Fritz Complete once they realize the value and added ammonia protection. Great for beginners, but not the long-term choice.
Check Price on AmazonHow to Use Water Conditioner Properly
During Water Changes:
- Calculate your water change volume - Use our Tank Volume Calculator if unsure
- Add conditioner to new water - Treat the water BEFORE adding it to the tank, or add conditioner directly to the tank right before adding new water
- Dose for the amount of new water - Not the total tank volume (unless doing a full water change)
- Wait 1-2 minutes - Let the conditioner work before adding to tank
Quick Dosing Reference:
- Seachem Prime: 2 drops per gallon, or 1 capful (5 mL) per 50 gallons
- API Stress Coat: 1 mL per gallon
- Fritz Complete: 1 mL per 10 gallons
- Tetra AquaSafe: 5 mL per 10 gallons
Emergency Ammonia Treatment:
If you have an ammonia or nitrite spike (common during cycling or after fish death), products like Seachem Prime and Fritz Complete can temporarily detoxify these compounds:
- Dose up to 5x the normal amount
- Effect lasts 24-48 hours
- Redose daily until water changes or bacteria catch up
- This buys time but doesn't fix the root cause - do water changes!
Which Water Conditioner Should You Choose?
Choose Seachem Prime if:
You want the best value and ammonia protection. Works for 90% of aquarists.
Choose API Stress Coat if:
You have injured fish, are adding new fish, or fish are recovering from disease.
Choose Fritz Complete if:
You want Prime-like performance at a lower price, especially for multiple tanks.
Choose Kordon NovAqua+ if:
You keep expensive fish (koi, discus) or want the most comprehensive protection.
Choose Tetra AquaSafe if:
You're a beginner and want something easy to find at any pet store.
Frequently Asked Questions
Do I really need a water conditioner for my aquarium?
Yes, if you use tap water. Municipal water contains chlorine and chloramine that kill fish. Water conditioners neutralize these chemicals instantly, making tap water safe. The only exception is if you use RO/DI water or well water that has been tested and confirmed safe.
What's the difference between chlorine and chloramine?
Chlorine is a simple disinfectant that dissipates naturally when water sits out for 24-48 hours. Chloramine is chlorine bonded to ammonia - it's more stable and does NOT dissipate on its own. Most US cities now use chloramine, so you MUST use a conditioner.
How much water conditioner should I use?
Follow the dosage on your specific product. Seachem Prime uses 1 mL per 10 gallons (2 drops per gallon), API Stress Coat uses 1 mL per gallon. It's generally safe to slightly overdose (up to 5x) in emergencies, but avoid chronic overdosing.
Can I use water conditioner with fish in the tank?
Yes. Most conditioners are fish-safe and designed for this exact scenario. Add the conditioner to the new water before or as you add it to the tank.
Seachem Prime vs API Stress Coat: Which is better?
Seachem Prime is better for value and versatility - it treats more water per dollar and also detoxifies ammonia/nitrite. API Stress Coat is better if you have fish with injuries or compromised slime coats. Many hobbyists keep both.
Does water conditioner expire?
Most water conditioners have a shelf life of 3-5 years if stored properly. Seachem Prime can last indefinitely according to the manufacturer. Signs of degradation include color changes, unusual smell, or reduced effectiveness.
Need Help Sizing Your Water Change?
Use our free calculators to determine exactly how much conditioner you need for your tank size and stocking level.