Description
Dr Tim’s Ammonium Chloride Solution 2oz — Measured ammonia source for fishless cycling with One & Only bacteria
A fishless cycle needs ammonia, and household cleaners bring surfactants and perfume with them while a pinch of dry salts is guesswork. Dr Tim’s Ammonium Chloride Solution 2oz (SKU: 81254001830) is a 60 mL bottle of reagent-grade ammonium chloride solution from Dr Tim’s Aquatics, made to feed One & Only Live Nitrifying Bacteria in a tank that has no fish in it yet. The concentration is 40 mg of total ammonia-nitrogen (TAN) per millilitre, dosed by the drop at four drops per 3.8 L (one US gallon), which works out to roughly 2 mg/L of ammonia-nitrogen per dose. Dr Tim’s states that most fishless cycles need the ammonia added three times, and on that basis the 2 oz bottle cycles an aquarium of up to 359 L (100 gallons).
The method follows Dr Tim’s One & Only directions: dechlorinate, add the bacteria, dose ammonia to an initial 2 to 4 ppm, test every day or two, and redose once ammonia and nitrite have fallen, adding fish only when both read zero. For larger tanks Dr Tim’s gives the conversion of 100 drops to 5 mL. A 120 L tank takes about 127 drops per dose, so the bottle covers three cycles of that size, while a 359 L tank uses it all. It is an ammonia source only, so it must never go into a tank holding fish or invertebrates, and a liquid ammonia and nitrite test kit is needed to follow the cycle.
Usage & Application
When to Use
- New freshwater or marine set-ups: Cycling the filter before any fish, shrimp or coral arrive.
- Tanks started with One & Only: The ammonia the live bacteria need when no fish are there to supply it.
- Quarantine and hospital tanks: Getting a bare tank’s sponge filter ready ahead of a new purchase.
- Filters kept running empty: Feeding an established biofilter after its fish have moved out.
Dosing & Administration Guide
- Dose rate: Four drops per 3.8 L of aquarium water, added after the bacteria with the filter running.
- Target level: An initial reading of 2 to 4 ppm ammonia; a 40 L tank takes about 42 drops.
- Redose: When ammonia and nitrite drop, add the same dose again, one or two more times.
- Finish: Add fish once ammonia and nitrite both test zero; water change first if either sits above 10 ppm.
Product Specifications & Highlights
Key Features
- Reagent-grade solution: Ammonium chloride without the surfactants or fragrance of household ammonia.
- Known strength: 40 mg/mL of total ammonia-nitrogen, so every drop delivers the same amount.
- Drop dosing: Four drops per 3.8 L, with no syringe or scales needed.
- Cycles up to 359 L: Three doses for a 100 gallon aquarium from one bottle.
- Companion to One & Only: Dr Tim’s own ammonia source for its live nitrifying bacteria.
Product Details
- Brand: Dr Tim’s Aquatics (USA)
- SKU: 81254001830
- Barcode (GTIN/UPC): 812540018304
- Product Type: Additives & Supplements > Fishless Cycling Ammonia Source
- Net Volume: 2 oz (60 mL)
- Concentration: 40 mg/mL total ammonia-nitrogen (TAN)
- Dose Rate: 4 drops per 3.8 L (1 US gallon), typically 3 doses per cycle
- Cycling Capacity: Up to 359 L (100 gallons) per bottle
- Companion Product: Dr Tim’s One & Only Live Nitrifying Bacteria
- Range Sizes: 2 oz, 4 oz (757 L) and 8 oz (1,514 L)
- Target Environment: Freshwater and marine aquariums with no livestock, during a fishless cycle


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