First off let me start by saying ,this is my fault and lesson learned so dont flame me,try and help if you can...I have had my 185 gallon for 6 months with a 55 gallon wet dry sump...I never add chemicals and have had perfect water ..I do approx a 40 % water change weekly and have crystal water with approx 25 cichlids 3-4 inches in length...So the other day I was going to clean the inside of the glass to get rid of that "haze"that forms on the inside..You can only see it in certain light.Its not a water problem,but anyways I had some algae destoyer from when I first got into this hobby because I thought I may need it someday,but never did.So I thought I will add some and maybe I wont have to do the maintenance (not lazy but wanted to see if it would work),It worked,killed every one of my cichlids within 24 hours...I did a 50 % water change after the first deaths within 12 hours and checked the water,still no problems,amonia 0ppm,ph normal,but maybe there was an amonia spike that I missed because I didnt check the water prior to the water change...or maybe the chemical got into the fishs bloodstream and made them toxic?anyways,should I wait a couple weeks to add fish or is my problem over?I dont think the tank needs to cycle again does it?Again all the parrameters are within normal limits and water is crystal clear...Im afraid to add fish for the feasr of what might happen...Please be helpful in your resonses..I know I screwed up and will never add another chemical to my once beautiful tank....oh and yes I follwed the directions on the algae destroyer for dosing....Thanks