Cichlid death

Question
QUESTION: I have been fighting my 75 gal fish tank for about 5 months.  I have had several African cichlids that have all passed on.  Long story short I was fighting to keep algae from growing in the tank and with multiple water changes and chemicals seem to finally have it under control.  In the process of fighting the algae problem I have lost all my cichlids.  Recently I purchase two African cichlids after having my water tested.  Ammonia, Nirtates, Nitrites all good.  Water was soft and Phosphate through the roof, which could explain algae problem I hear.  Just before aclimating the fish I adjusted the PH from about 7 to 8.2.  The fish only survived about 24 hours before they perished.  The fish developed what looked to be cataracts on their eyes and worn whitish fins, like they were being eaten away by chemicals and were nose down in the tank.  All of the other cichlids have perished in the same fashion.  I have done complete water changes, partial water changes and nothing seems to work.  I have 1 power head undergravel filter and a canister filter currently installed.  Seeking advice on where to go from here changing the tank of death to the cichlid haven.

ANSWER: Hi Shawn,
 I never use chemicals to deal with algae. Algae grows because of an excess of food in the water and too much light.  I do not know why you have such high phosphate levels.  
With "chemicals" in the water, it is hard to know what caused the fish to die but it sounds (from the cataracts) like they had a very bad reaction to your water.

  Might I suggest you try keeping some convict cichlids.  They are much more tolerant of water conditions.  

  Also, what kind of gravel/substrate do you have in the tank?

-- Ron C.
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>


---------- FOLLOW-UP ----------

QUESTION: The tank has polished pebbles or river rock for the media, approx 40-50 lbs.  I have not added any algaecide to the water in well over a month.  The only chemicals that have been added are aqua safe, Ph up, and cichlid essentials.  
Since my e-mail I have also added some salt and started on a 7 day treatment of melafix.

Answer
Hi Shawn,
  This is all very peculiar.  Just to be sure, I assume that you are not using any soaps, or any other kinds of cleaners in or anywhere near your tank, right?

  Why I suggested convicts is because they can live at pH 7 which your water seems to be, then you don't need to add any pH buffers. They also don't need/want the salt. And you don't need the melafix.  If we eliminated all of those, and the fish still die, then that tells us something else is wrong and we can try to figure out what that is.

-- Ron C.
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>