So I am new to fish keeping and am looking for some pointers. I have a 10 gallon live planted tank that is about a month and a half old, fully cycled. I have 3 neon tetras that have been alive in the tank through the cycling process and am trying to add in 2 guppies. The guppies keep dying though and i cannot figure out why. My GH is around 180, KH 220 and PH around 8 nitrite 0 and nitrate under 10. These seem to be alright values with the PH stable but on the higher end. I have gone through 2 rounds of guppies and for some reason they wont stay alive but after about a day or two just stop eating and then will pass shortly after that. The only thing I could think of was the PH or the temperature. I currently dont use a heater ( I have one) because my house gets warm during the summer and the water never gets below 77. The water does fluctuate though between 77 and 82. Is that a problem? With the 82 being about 3-4 and then dropping to 77 at night. I am not sure if i should be using the heater to keep the water at 80 because i fear if i do that the upper temperature will also rise 3 degrees to 85 due to the water not cooling at night. thoughts on this would be great? Do i need to lower my PH or do you think it is a problem with the temperature?