urgent ! need help i have a small pond prob about 300 gallon at the min which i am using as a holding tank my water is quite murky but have tested for ph amonina and nitrate all seem very good i have many plants a waterfall and air pump running constently over the last month or so i have had many fish die koi and goldfish they started showng signs parasites so i treated them acordingly this didnt work and i saw signs of cotton wool like strands from the gils i have regularly salted water and tryed anti fungus .they dont seam to have any energy and seem to dift about on the top or swim into a corner and not move. i am running out of ideas and really want to get them well before finishing off my bigger pond and intoducing them to it please please can u help thanks rob