conditioner

Question
hi trish you helped me before in the past i hope you remember anyway my new problem is as follows i have a 60 liter tank its cycled for about a month i have
3 guppys small
3 mollies small
1 neon tetra small
2 gouramis medium size
1 sword tail 2 inches
1 clown loach 2 inches
1 platy medium
my nitrite natrate ph everything was perfect last night when i tested the water but this morning a swordtail died suddenly i got the water tested again at the pet store and they said the nitrite and nitrate and ph was very slightly over i put extra prime in the tank i want to ask you do you think i should do a water change i feed them 2 pinches of flake every 2 days the tank is well aired and has 3 live plants as well ive also stired the gravel so the filter can take away excess waste  

Answer
Hi Amar.  I want to ask you a question and have you get back to me before I give you an answer to this question.  Reply to this as a follow up so that I have the original question, please.

You said you tested the water and it was fine last night. But when the pet shop tested it, there were troubles.  Here is my question:  What type of test kit do you use (Dip sticks or a Master Water Test Kit) and what type did the Pet Store use (Dip Sticks or Master Water Test Kit).

I'll explain why to you when you get back to me.  I'll wait to hear from you, and I'll get back to you ASAP.   ;o)