Algae Eaters dying

Question
I have a 10 g tank with a black moor and a goldfish.  The tank has gotten pretty dirty lately and I decided to get an algae eater to help with that.  I wanted to get one anyways, so I figured now was a good time to get one.  I bought a chinese algae eater and put into the tank in the afternoon.  By the next morning it was dead.  I then figured it was caused by the filter pump failing overnight, so I bought a new filter system and a new algae eater.  This one was again dead by the next morning.  What could be wrong with my tank to be causing them to die?

Answer
Have you checked the nitrite, nitrate ammonia levels in the aquarium? Sounds  to me like the water quality is not at safe levels. The fish you have in there already, may have adapted to the quality of water. the new fish from the pet store are probably in water that is perfect condition, and then when you introduce them into your tank, its a shock to them. Try testing the water parameters and see if this could be an issue. Sounds like it to me. Good luck. If you have any other questions, feel free to contact me  By the way, quick dip makes a test strip that tests the main 6 components all at once. I use it all the time.