Key water parameters and ideal ranges for most aquatic life
- GH -- 4 to 8 degrees
- KH -- 2 to 6 degrees
- pH -- 6.5 to 7.5
- Ammonia (NH3) -- 0 ppm
- Nitrite (NO2) -- 0 ppm
- Nitrate (NO3) -- 10 to 40 ppm
- Phosphate (PO4) -- 0 to 0.2 ppm
- Potassium (K) -- 20 to 30 ppm
- Carbon dioxide (CO2) -- 20 to 30 ppm
- Water temperature -- 68F to 80F
GH (general hardness) measures concentration of calcium and magnesium ions
- Supports skeletal structure of fish, and shrimp and snails (exoskeleton)
- Contributes to enzyme activity and osmosis regulation for both animals and plants
- GH should be 2 degrees higher than KH, GH should not be lower than KH
KH (carbonate hardness), measures the concentration of carbonate and bicarbonate ions
- Stabilizes pH by buffering against drastic changes
- If KH is 0, the pH can fluctuate excessively, because there is no buffering of pH, hurting plants and animals and algae will come
- Plant melting is a good indication of low KH
- KH should be 2 degrees lower than GH, KH should not be higher than GH
pH (potential of hydrogen), measures acidity or alkalinity
- Stable pH is crucial for the biological processes of both fish and plants, and for the stability of certain chelated plant nutrients
- Photo period pH with CO2 injection active should be about 6.8, on the acidic side
- At night, with CO2 injection inactive, as plants stop photosynthesis and CO2 dissipates, pH typically rises by about 0.5 unit to 7.3
Ammonia (NH3 or NH4+), ammonia, ammonium is highly toxic to aquatic life and must be kept at 0 ppm
- In an established aquarium, beneficial bacteria in the filter and substrate convert ammonia to nitrite and then to nitrate (biological filter -- the nitrogen cycle)
- A bad smell usually indicates that there's some decaying organic material in the tank (uneaten food, dead plant or animal, fish waste) producing excess ammonia that the biological filter is failing to process
- Determine the source of the foul odor and eliminate, and do a water change to get rid of ammonia
Nitrite (NO2), toxic to aquatic life and must be kept at 0 ppm
- An intermediate product in the nitrogen cycle (biological filter)
- Usually spikes at beginning of an aquarium's life cycle
Nitrate (NO3), less harmful than nitrite, but still toxic in excess, should be kept within 10 to 40 ppm
- Serves as a nutrient for plant growth, but too much stunts plant growth and spurs algae growth
- Animal life can also suffer from excessive level of nitrate
Phosphate (PO4, phosphorus combined with oxygen), supports plant growth generally
- Should be limited to no more than 0.2 ppm to prevent algae proliferation
- Some aqua soil substrates absorb phosphate from the water column during initial weeks after setup, then after several months can release it back into the water, causing unexpected surges in phosphate levels
- Regular water changes help control phosphate level
Potassium (K), crucial for plant health
- Aids enzyme function, photosynthesis and osmosis regulation
- Plant nutrient not supplied by decaying organic material, so must be supplemented with fertilizers
- Drops in potassium level can stop plant growth
Carbon dioxide (CO2), essential for photosynthesis in aquatic plants
- Recommended level in water column: 20 to 30 ppm
- Proper CO2 levels not only support plant growth, but also help stabilize pH
- A CO2 drop checker is good way to monitor CO2 level in the water column
- The drop checker solution should show lime green at peek CO2 injection period
- Yellow solution indicates excessive CO2 level, while blue indicates low CO2
- CO2 level can also be calculated based on KH and pH (google the chart)
Water temperature: 68F to 78F is ideal for most aquariums, for fish and plant health, as well as the beneficial bacteria of the biological filter (nitrogen cycle).
- Ammonia production due to organic decomposition and waste products is accentuated in temperatures above 75F
- Algae growth is also greater in temperatures above 75F
- Nevertheless, temperature must be adjusted either higher or lower depending on particular fish or plant species
- Temperatures below 68F make most tropical aquatic life susceptible to disease, and it diminishes the effectiveness of the beneficial bacteria providing the biological filter
Maintaining stable water parameters
- For new tanks taking time is the most important factor for water parameter stability
- New tanks should wait a few weeks before introducing heavy bio loads
- The new ecosystem needs time to fully develop to support itself, largely to grow adequate bacteria colonies for the nitrogen cycle
- Generally, the longer a tank runs the more resilient it becomes to changes and potential problems
- There are many different species and varieties of microorganisms that can help stabilize water parameters, and it takes time for them to become established in the system (eg., beneficial bacteria)
- Plants help maintain stable water parameters, and they require time to adapt to a specific tank
- Most aquarium plants are grown out of water (emersed) for convenience, and they must adapt to underwater conditions (submerged)
- Usually entails melting, shedding leaves, and growing back new leaves from the base
- This adjustment period can take weeks or even months
- Once established plants can act as a buffer against water quality issues
- Plants consume ammonia in the form of ammonium, using it as a nitrogen source for growth
- Plants are crucial for natural biological filtration alongside bacteria
- Plants help offset toxic buildup and improve water quality by reducing ammonia, nitrite, and nitrate in the water column
Stable water temperature helps maintain overall water parameter stability
- Stable temperature benefits fish, snails, shrimp, plants, and microorganism colonies
- Small, gradual temperature shifts usually present no problems, but large, sudden shifts can harm the entire ecosystem
Beware of making too many unnecessary changes in the tank that might upset the balance
- This can include adding new hardscape, new plants or animals, new fertilizer routines, changes in GH or KH, etc
- Make changes slowly and incrementally to avoid sudden shifts in water parameters, give tank ecosystem time to adjust to new conditions
Ammonia, nitrite, and nitrate levels are among the most volatile parameters
- Overfeeding results in spoilage that produces ammonia that can outpace the bacteria responsible for converting ammonia to nitrite and nitrite to nitrate
- A dead organism, like a fish, decaying produces ammonia that can outpace the bacteria that are accustomed to dealing with a lighter ammonia load
- Of course, with more ammonia in the ecosystem, the bacteria colony will adapt and grow, but that takes time, and meanwhile the ammonia and nitrite spike could prove lethal to tank inhabitants
- As noted above, plants help regulate ammonia, nitrite, and nitrate levels, too
Toxicity of ammonia
- Harmful even at low levels, anything above 0 ppm being a sign of imbalance in the biofilter (bacteria mainly)
- Levels above 0.25 (measured by the API test) are considered toxic and require action such as daily 25% (or greater) water changes until ammonia level drops to 0
- 0.02 to 0.05 ppm -- chronic stress and tissue damage (especially to gills) begin
- 0.2 to 0.5 ppm -- acute level, many fish show signs of distress
- 2.0 ppm+ -- lethal for most sensitive aquatic species, including plants
- Temperature and pH matter to toxicity of ammonia
- The actual toxicity of ammonia readings can vary depending upon temperature and pH
- Eg., an API ammonia test reading of 0.25 ppm indicates greater toxicity if the water temperature is 78F and pH is 8.0, than if temperature is 72F and pH is 7.2
Toxicity of nitrite
- Nitrite is harmful at any level, especially above 0.25 ppm, ideal level is 0
- Nitrite interferes with oxygen transport in fish blood, and even slight spikes (like 1 ppm) can cause stress and be lethal, requiring immediate water changes
- Toxicity levels
- 0.25 ppm -- indicates poor biofiltration
- 0.5 to 2 ppm -- significant toxicity, causing stress and lasting harm
- Above 2 ppm -- highly dangerous, lethal, requiring immediate large water changes, 50% or more daily to dilute nitrite until the biofiltration of the ecosystem can handle the nitrogen cycle load
Toxicity of nitrate
- For fish only aquariums nitrate levels above 40 to 50 ppm can cause stress, prone to disease, and reduce lifespan
- Planted aquariums can utilize higher levels (40 to 60 ppm) for plant fertilizer, using regular water changes to keep levels in check
- While nitrates are less toxic than ammonia or nitrite, keeping levels below 40 ppm is a safe goal, while lower levels may be required for sensitive species
- Toxicity levels
- 0 to 20 ppm -- ideal, safe for sensitive species and for preventing algae blooms
- 20 to 50 ppm -- safe/acceptable, most hardy fish tolerate this range, recommended for planted tanks because plants require nitrate as a primary nutrient
- 50 to 100 ppm -- undesirable, stressful, weakened immune systems
- 100+ ppm -- dangerous, can cause chronic stress and susceptibility to disease
- 800+ ppm -- lethal for most common fish species
- Weekly partial water changes (25%) are recommended for managing nitrate buildup
Benefits of nitrate
- Plant growth, nitrate (NO3) provides nitrogen which is a crucial nutrient for aquatic plants
- Useful as an indicator of nitrogen cycle functioning, converting toxic ammonia and nitrite into a manageable form
- Algae control by providing nutrients to plants, fueling growth enough to out compete algae for nutrients, starving algae out
Water hardness and pH stability
- GH, KH, and pH all fluctuate somewhat due to the carbonate cycle consisting of the beneficial bacteria consuming carbonates while converting ammonia and nitrite to nitrate (nitrogen cycle), lowering KH and its ability to buffer pH swings
- The beneficial bacteria that breakdown ammonia need KH to live (feeding on carbonates)
- If KH drops low enough, the bacteria that feed on it will suffer, potentially causing an ammonia spike
- KH level needs to be monitored and periodically adjusted
- Raising KH and Raising GH (ideally, GH should be 2 degrees higher than KH
- Depending on the KH of one's tap water, KH can be raised via water changes
- KH can also be raised by adding baking soda (sodium bicarbonate), 1/4 teaspoon per 5 gallons raises KH approximately 1 degree, replacing the carbonates consumed by the beneficial bacteria.
- Note that adding baking soda to the water column can also raise pH
- To raise GH add Seachem Equilibrium, 1/4 tsp per 5 gallons raises GH approximately 1 degree
- GH and KH should be tested weekly to ensure proper levels for ecosystem stability, note: make only small incremental changes at any given point, allowing the ecosystem time to adjust/adapt to the changes
Avoid over stocking your aquariume
- Too many inhabitants can outpace the capacity of good bacteria to handle the bioload, causing elevated ammonia levels and other instabilities in the water parameters
- Still, the capacity of the biofilter will grow to accomodate the bioload within reasonable limits
Regular water changes help maintain stable water parameters