Let's look at this right here...
4 months ago you sold off old fish stock...= zero bio-load
water only ...........................................= zero bio-load
zero Ammonia,zero nitrIte,zero nitrAte.....= new tank perameters
6.5ph (what comes out of your tap?)
6.5 is a few tenths lower than most all of the LFS I have ever got fish from...
Here's what I suggest...
1st off cycle your system, you killed off all your benificial bacteria with 4 months no bio-load...
I swear by fishless cycling, using pure ammonia...
After you are properly cycled, check the perameters you'll have some nitrAtes not ZERO...
Make sure the LFS ph is what your tank is, or closer, add more than 2,
or less than 2 Jardinis...I don't even want to get into the odds of 2 Jars making it for too very long...
I don't know why somebody didn't see this earlier...