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Fish/Discus PH


Hi Ron---I just bought 2 new young Discus and they don't like the high PH of tap water.  I added "pH decrease" a few times but the pH remains like 7.2-7.4.   What's the best way to lower the pH of my tank?  (they're expensive & I don't want to lose them)



Hi Larry,
 Discus are rather sensitive fish so the most important thing is that any adjustments you make to water chemistry, such as pH, you do gradually. I suggest you add more of the pH decrease over the next week or so to see if you can get it down to 6.8 or something like that.  Then over time try to get it a little lower.  Do NOT try to get it down to 6 in a few days.  That will most likely kill the discus.

-- Ron C.
  Cichlid Research Home Page <>


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Ron Coleman


I am an expert on cichlid fishes, particularly New World cichlids. My broader expertise includes the behavior, ecology and reproduction of fishes in general. (I am NOT an expert on Goldfish). Please do not use abbreviations, such as "my GT has a swollen eye" because I don't know what a "GT" is. The more clearly you can explain your question, the better chance I have of understanding what it is that you seek. I keep fishes both as a scientist and as a hobbyist and I currently maintain about 140 aquariums.


I am an Associate Professor at the California State University, Sacramento in the Department of Biological Sciences, and I run a website, called the Cichlid Research Home Page . I also write for many popular aquarist magazines, and I was editor of Cichlid News magazine for several years. I am a scientist and I spend my time teaching fish biology, ecology, behavior and evolution and doing research on the reproductive biology of fishes, particularly cichlids. I do research in the laboratory and in Costa Rica, Nicaragua and Mexico. My main interest is understanding the evolution of parental care in fishes. I am interested in encouraging greater public awareness, understanding and participation in science.

Cichlid News, Tropical Fish Hobbyist, Freshwater and Marine Aquarium, Science, Behavioural Ecology and Sociobiology, Copeia, Canadian Journal of Zoology, Trends in Ecology and Evolution, AUK, Environmental Biology of Fishes

PhD (Toronto, 1993) MSc (Simon Fraser, 1986) BSc (British Columbia, 1983)

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