Hmmm.....
A couple of strange things I see here. I read quickly over your posts when you had the prior fishkill and now this new thread about restocking. One thing I noticed is....from the numbers you report on your pH, it seems to be bouncing around like mad. On 7/11 you post that it is 6.5. On 7/12 you post that it is 6.6. On 7/13 it is 7.0. and once on 7/16 it is 6.2, and at another later time on 7/16 it is slightly over 6.0. If your ph truly changes so much, nothing is going to ever survive in your water. These are huge swings in the fishy world.
Also, IMO you don't need salt unless one of the fish isn't feeling well. I read that you are adding 1 teaspooon to every 5 gallons, so that would be about 6 teaspooons for your 29 gallon tank? What you don't say is how big your water changes are, how often the water changes are, and how much salt do you replace back into the tank when you do a water change? You may be also overdoing it with the salt...and live plants will surely die with salt in the water.
Added: Just went back to check your previous posts, thought that you had said you had a pleco. For sure plecos do not like salt, just an fyi for the future.
Debbi