Water chemistry is the foundation of successful aquarium keeping, whether you’re maintaining a freshwater community tank or a complex reef system. Understanding and maintaining proper water parameters is crucial for the health and longevity of your aquatic pets.
The Nitrogen Cycle is the most fundamental chemical process in any aquarium. Fish waste and uneaten food produce ammonia (NH3/NH4+), which is highly toxic to fish even in small amounts. Beneficial bacteria convert this ammonia into nitrite (NO2-), which is also toxic. A second group of bacteria then converts nitrite into nitrate (NO3-), which is less harmful but still needs to be managed through regular water changes.
Key Parameters to Monitor:
Ammonia (NH3/NH4+):
– Should always be 0 ppm in an established tank
– Test at least weekly, more frequently in new setups
– Signs of elevated levels include gasping at the surface and red gills
– Emergency treatment includes water changes and ammonia-neutralizing products
Nitrite (NO2-):
– Should always be 0 ppm in an established tank
– Can cause brown blood disease by preventing oxygen transport
– Monitor closely during tank cycling and after adding new fish
– Regular water changes help control spikes
Nitrate (NO3-):
– Should be kept below 20 ppm in most freshwater tanks
– Reef tanks often require levels below 5 ppm
– Remove through water changes and live plants
– High levels can stress fish and promote algae growth
pH Levels:
– Freshwater: typically 6.5-7.5, varies by species
– Marine: 8.1-8.4
– Stability is often more important than exact value
– Avoid sudden changes which can shock fish
– Buffer solutions can help maintain stable pH
General Hardness (GH):
– Measures dissolved calcium and magnesium
– Important for fish osmoregulation
– Different species have different requirements
– Can be adjusted using commercial products or RO water
Carbonate Hardness (KH):
– Acts as pH buffer
– Prevents pH crashes
– Marine tanks require higher levels (8-12 dKH)
– Test weekly and maintain stability
Testing and Maintenance:
1. Invest in quality test kits – liquid tests are generally more accurate than strips
2. Establish a regular testing schedule
3. Keep a log of test results to track trends
4. Perform regular water changes based on test results
5. Use RO/DI water if tap water quality is poor
Common Problems and Solutions:
– pH Crashes: Often caused by low KH, add appropriate buffer
– Ammonia Spikes: Perform water changes, reduce feeding
– High Nitrates: Increase water changes, add live plants
– Unstable Parameters: Check filtration, adjust maintenance routine
Prevention is always better than cure. Regular maintenance and testing help avoid most water chemistry problems before they affect your fish. Understanding these fundamental parameters and their relationships will help you maintain a healthy, thriving aquarium ecosystem.