salt h2o going hay wire

Question
I have had this salt tank for two yrs, and the same people who set it up they have always cleaned it, any way this past Nov they did there ususl cleaning and as they were cleaning they were telling me a story that the last tank they had cleaned the night before, that next morning they recieved a call telling them that all the fish were dead.  any way the next day all of my fish were dead (mind you they were just as old as the tank and quite large and very expensive)  So I told the people and they said that it had to be becauseI have bad water, I have had the same H2o from the same faucet sence the tank was started.  Also the fact that they marveled about how beautiful the tank always is (was) so can you help?  I have so much alge on every thing .I t is sad.  Thank You.

Answer
Hi there, Do you check the levels? Algae feeds off excess nutrients (ie nitrates) If you weren't keeping a check on this and they were too high, the algae will grow and it will affect the fish in time. However, I find it a bit suspicious for them all to die at once and for the people who "clean" your tank to just put it down to bad water is a bit odd. They should be testing the water before a water change and changing the water to bring any levels that are out down. No more than about 10-15 should be changed on a regular basis at once, or even 20-25 if there is a problem. Too much could crash the tank which may cause fish to die. To get rid of the algae you need to do about a 25 water change and keep the lights on for shorter periods (about 6 hrs) until it clears. Hope this helps.