The PH level is 7.5. Yes, its newly setup, some of the fish were new, some were transfered from the old tank. I just net them into the new tank with a fish net.
As for the addind of anti-chlorine and salt, i added them 5 mins before the fishes goes into the tank, i place about 3 tea-spoon of aquarium salt. Regarding the tank size, i don't know how to measure in gallon, i just know that its a 2-feet tank. Yes, i add all the fishes at the same time.
For more information, I have 80 neons, 4 rummy nose, 6 swordtails, guppies left 1. And two aquarium plants. Hope you could help me figured out whats wrong with the water or maybe the fishes. Sometimes have 1 neon tetra died with any death symtoms. No tetra diseases, no fins rots etc.