Baking powder is a common ingredient used in baking to help dough and batters rise. It is made up of bicarbonate of soda (baking soda), cream of tartar, and sometimes cornstarch. When baking powder is mixed with water, a chemical reaction occurs that produces carbon dioxide bubbles. These bubbles cause baked goods to rise.
While baking powder helps make baked goods light and fluffy, some people wonder if it can be harmful to fish if it enters waterways. In this article, we’ll look at whether baking powder can impact fish and aquatic life.
Does baking powder harm fish?
The short answer is that small amounts of baking powder are generally not toxic to fish. However, large quantities of baking powder can reduce oxygen levels and increase water alkalinity, which can stress or kill fish.
How baking powder works
To understand how baking powder affects fish, let’s first look at how it works. The key ingredients in baking powder are:
- Bicarbonate of soda (baking soda) – This is alkaline and reacts with acids to produce carbon dioxide bubbles.
- Cream of tartar (potassium bitartrate) – An acidic powder that reacts with the bicarbonate soda.
- Cornstarch (optional) – Helps keep the mixture dry.
When baking powder is mixed into water or a batter, the baking soda and cream of tartar react, breaking down into carbon dioxide, water, and potassium sulfate. It’s the carbon dioxide that creates bubbles and makes baked goods rise.
Effects in water
When baking powder reacts in water, the same chemical reaction takes place. This reaction increases the alkalinity of the water due to the baking soda. Higher alkalinity means there are more carbonate and bicarbonate ions in the water.
The carbon dioxide released can also reduce oxygen levels in the water as the gas bubbles dissipate. Both high alkalinity and low oxygen can stress and ultimately kill fish if the changes are significant.
However, small amounts of baking powder in ponds or streams are unlikely to cause major changes in water chemistry. Studies show baking soda concentrations up to 50 mg/L had no adverse impact on rainbow trout. So occasional exposure to traces of baking powder is not typically dangerous to fish.
Amounts that could be harmful
While small amounts are fine, larges doses of baking powder can impact aquatic life:
- Oxygen levels – Carbon dioxide released from large amounts of baking powder can reduce oxygen in the water. Oxygen levels below 3-4 mg/L are dangerous to most fish species.
- pH levels – Excessive baking soda will dramatically increase pH. Levels above 8.5 harm fish, and pH over 9.5 can cause fish kills.
- Toxicity – Very high concentrations of baking soda (over 1000 mg/L) may directly toxic to fish due to osmotic stress.
For reference, normal pH for freshwater fish ranges from 6.5 to 8.0.
Lab study on zebrafish
A 2018 laboratory study looked specifically at how baking powder affects zebrafish. Scientists added 5 grams of baking powder per liter of water (5000 mg/L).
They found this extremely high concentration stressed the zebrafish:
- 88% mortality after 12 hours
- Increased mucus on skin and gills
- Damaged gill tissues
- Signs of oxidative stress
So in toxic amounts, the alkaline water and reduced oxygen can damage fish gills and cause death. However, 5000 mg/L is far above levels fish would encounter in ponds, lakes or streams.
Will baking powder hurt pond fish or wild fish?
For fish living in normal outdoor environments, small amounts of baking powder are not generally harmful.
A typical pond requires about 1 teaspoon (5 grams) of baking powder to raise pH and carbonate hardness. This tiny quantity will not impact oxygen levels or pH enough to harm pond fish.
Likewise, traces of baking powder entering streams or lakes from residential or commercial discharges would quickly dilute and be rendered harmless.
It takes extremely large quantities of baking powder to negatively impact wild fish. It would take dumps of hundreds of kilos of the powder to alter water chemistry enough to damage fish gills or reduce oxygen to dangerous levels in ponds or small lakes. These scenarios are unlikely.
So you don’t need to worry about occasionally using baking powder in or near bodies of water containing fish. Just don’t dump excessive amounts directly into ponds or lakes, and avoid regularly discharging large volumes of baking powder contaminated water.
Effects on other aquatic animals
Research also shows baking soda and powders only harm other aquatic animals at very high concentrations:
Shellfish
– Oysters and mussels are unaffected by levels up to 1000 mg/L.
– Levels of 2500-5000 mg/L reduced survival and growth rates.
Crabs
– No mortality for crabs at 1000-2000 mg/L baking soda.
– 5000 mg/L caused 60% mortality after 14 days.
Shrimp
– Levels up to 500 mg/L had no effect.
– Mortality observed at 1000 mg/L.
Amphibians
– Tadpoles showed slowed development and reduced growth at 7000-30,000 mg/L.
– Toxicity effects seen at very high concentrations of 44,000-69,000 mg/L.
So again, normal levels of baking powder released into the environment are highly unlikely to affect these aquatic animals.
Can baking powder affect aquatic plants?
High alkalinity can reduce germination rates and stunt the growth of some aquatic plants. But baking powder would have to greatly increase pH to levels beyond what most freshwater plants can tolerate.
One study found that giant duckweed (Spirodela polyrrhiza) had:
- Optimum growth at pH 5-7
- Reduced growth above pH 8
- Failed to grow at pH 10
Such high pH values are only likely near large accidental spills of baking soda or powders. Typical exposure to small amounts of baking powder will not impact aquatic plants.
Furthermore, some aquatic plants may benefit from traces of baking powder in water bodies with low alkalinity and soft water. Small boosts in carbonates can provide essential nutrients for plant growth.
Can fish benefit from baking powder?
While large quantities of baking powder can harm aquatic life, small amounts may actually benefit some fish species. Here are two potential benefits:
Increasing carbonate hardness
Adding a pinch of baking powder to very soft, acidic waters can raise carbonate levels and stabilize pH closer to neutral. This creates better conditions for fish that prefer harder water. Aquarists sometimes add baking soda for this purpose.
Treating parasites and infections
A dip in alkaline baking soda baths can help remove parasites like ich from fish skin and gills. The alkaline water may disrupt the parasite life cycle or damage the protective slime coat. Baking soda is sometimes used to treat fungal infections for amphibians as well. Of course, levels and timing must be carefully controlled to avoid harming the fish.
Conclusion
Small amounts of baking powder dissolved in ponds, lakes, or streams are generally harmless to fish, aquatic animals, and aquatic plants. The tiny increases in pH and carbon dioxide levels get diluted and dissipate quickly without impacting aquatic ecosystems.
However, directly dumping large quantities of baking powder could reduce oxygen levels and create overly alkaline conditions that damage gills, stress wildlife, and potentially cause fish kills. But such high concentrations are rarely reached from normal uses of baking powders.
In moderation, baking powder is not dangerous to marine life. Just avoid intentionally adding cups of the powder directly into bodies of water. Also be mindful that other aquatic animals are even more sensitive to alkaline conditions than fish.