fish dying (long Post)

[pirate]

Ok I found a large dead snail in my tank still no yellow tail. I have no co2 tank at all. Its a very simple system. PH right now is 8-8.5. is it still to low? How do I raise it?
For my fresh water dip I get the temp the same as my tank and put the new fish into the water ( water stands for a day or more, taken from my ato tank) And he stays for approx 5 mins.
I've aimed a power head from the bottom of the tank to the surface.

Thanks for all the help so far guys.