If you really want happy, healthy, vibrant discus, then keep them in acidic water. Discus are susceptible to bacteria infections. The higher the pH, the more likely your discus will get a bacteria infection. People that keep their discus in high pH eventually will have problems. My Dad likes to say, "raising discus in alkaline water is like raising tomatoes in the shade." It really isn't good for them. In the long run you will have problems. If you read the various tropical fish forums on the net, most of the people that have problems with their discus have their fish in water with a pH higher than 7.2.
Here's an example. Just read this entire thread over at another forum.
http://www.aquaria.info/index.php?name=PNphpBB2&file=viewtopic&t=66967
He should have never kept his discus in water with a pH of 8.0.
Here's an example. Just read this entire thread over at another forum.
http://www.aquaria.info/index.php?name=PNphpBB2&file=viewtopic&t=66967
He should have never kept his discus in water with a pH of 8.0.