At 09:44 PM 6/13/98 EDT, you wrote: >carbonate reduction using muriatic acid,. I've succeeded in reducing it from 80ppm to 40 ppm, I think that is about as low as you are likely to get without resorting to RO. Folks who do discus often use straight RO water (less that 100ppm TDS). You might want to consider that if you have a similar goal. - -- Dave Gomberg, San Francisco mailto:gomberg@wcf.com FormMaestro <http://www.wcf.com>