i have a 65 gallon tank, i drilled it and plumbed it, 20 gallon sump, about 32 pounds of live rock and 60 pounds of sand. about 3 weeks ago my dad was playing with the plumbing and got abs cement in the water, and it killed all of my fish. the hermit crabs lived.so what i did was basically started over again, i did a fresh water dip with the rock, rinsed the sand , rinsed all the media, and started over with all fresh water, within a week i had a brown algae bloom, and a week after that the green started growing. although i havent tested my water , i figured it should be ok since there is algae growth, anyways i bought a banded cat shark on friday, and saturday morning it was dead, i am so down about this , loosing all my fish, and now killing a shark, is it possible there is still chemicals in the tank even though i cleaned everything and started fresh? maybe it was a mistake not to test the water, but from expericne it should havebeen fine, i use a ph buffer as well so i know the ph is fine. and when i did the sump from a brand new 20 gallon tank, i used GE 100% silicone window and door. any advice?