FAQs • Alameda County Water District, CA • CivicEngage

Do chloramines have to be removed if only a small amount of water is added to an aquarium or pond to make up for evaporation loss?: To know for sure, you'll have to monitor for total chlorine residual. Chloramine residuals in water used to keep fish should be kept below 0.1 mg/L. Total chlorine test kits are available from pet stores, pool supply stores and chemical supply houses. Make sure, however, that the kit is for "total chlorine" or "combined chlorine," not "free chlorine." A free chlorine test of chloraminated water would read zero but still be toxic to fish.

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Chloraminated Water & Your Pet Fish

1. Why are chloramines toxic to fish?: Chloramines are safe for humans but toxic to fish. When chloramines, a combination of chlorine and ammonia, break down either naturally or through the use chlorine removing chemicals, ammonia is released. The ammonia can be removed from fish tanks or ponds by using commercial products available at pet supply stores. Biological filters, natural zeolites and pH control methods are also effective in reducing the toxic effects of ammonia.

2. Are chloramines toxic to both saltwater and freshwater fish?: Yes. Chloramines affect saltwater fish in the same way they affect freshwater fish.

3. Do chloramines pose a hazard to koi?: Yes. Koi are just as susceptible to chloramines as other fish.

4. Will letting water sit for a few days cause chloramines to disappear?: No. Unlike chlorine, which dissipates when water sits for a few days, chloramines may take weeks to disappear.

5. Do chloramines have to be removed if only a small amount of water is added to an aquarium or pond to make up for evaporation loss?: To know for sure, you'll have to monitor for total chlorine residual. Chloramine residuals in water used to keep fish should be kept below 0.1 mg/L. Total chlorine test kits are available from pet stores, pool supply stores and chemical supply houses. Make sure, however, that the kit is for "total chlorine" or "combined chlorine," not "free chlorine." A free chlorine test of chloraminated water would read zero but still be toxic to fish.

6. Will a carbon filter remove chloramines?: No. Most carbon filters will not remove chloramines.

7. Will reverse osmosis remove chloramines?: No. Salts can be caught by the permeable membrane but chloramines pass through easily.

8. Will boiling remove chloramines from water?: No. Boiling is not an effective way to remove chloramines from water. The only practical methods of removing chloramines from water are using a water conditioner which contains a dechloraminator or by using a granular activated carbon. Ask your pet supplier for instructions on how to use these products.

9. Who can I contact if I have additional questions about chloramines?: If you have questions or comments about chloramination, please contact ACWD at (510) 668-6500.