Thanks for that, I have now intoduced myself on the wellcome page.
Re. the sick discus, he is probably 6-7 months old and I aquired him 5 weeks ago. The tank is 300l and has 3 other recently intoduced discus sub aldults in it. The filter seems to be doing its job, no ammonia, no nitrite and minimal nitrate, PH 7.4 consistently, temp. 30C. I do a 50% water change every second day with aged, declorinated, 30C water, the tank is bare bottomed and I srub the glass every week. I feed Novo bits beefheart and blood worms.
The white poo was not stringy it was literaaly like cloudy mucous. I have moved him to an isolation tank and upped the temp to 33c and added 2 tablespoons of salt per gallon of water and he seems to be taking a little food.
Hope this might give someone some clues.
Cheers Chris