RE: First Proper Fishless Cycle (am I doing it right?)
to the forum!
The PH might be 7.4 or 7.6 in your case. It isn't a problem you should be worry about. Both are just fine. It is possible that the PH had dropped from 7.6 to 7.4, and it is normal. My own tap water has PH of 8.0, but once it's added into my aquarium it is 7.8~7.9.
What filter system are you using?
You are doing just fine from the look of it. While some people might tell you that there is no need to add ammonia twice a day, my personal opinion is you can slightly boost the bacteria growth by always have ammonia in your tank during the entire fishless cycling. Sure the bacteria won't starve to death right away when the ammonia is down to 0ppm, but they won't continue to grow in number either after the food source (ammonia) has run out.
During my own fishless cycling, I was adding ammonia once a day but I dosed more than 5ppm each time. By the end of my cycling, my aquarium was naturally able to convert all the 5ppm+ ammonia to nitrate within 24 hours. I added full stock of fish no problem with no trace of ammonia or nitrite.
What you need to be careful about is the sudden PH crash from too much nitrate. The production process of nitrate is acidic, and it will eat away the water buffer. Once all the water buffer is gone, you might see your PH suddenly become 6, 5, or even lower. Bacteria don't grow well in acidic environment. So when that happens, you will need to immediately do a large percentage partial water change to restore the water buffer and PH.
Tetra safestart is indeed a wonderful live bacteria product. You can finish your fishless cycling within days. In the worse case, it should be no more than 2 weeks.
Please keep us updated. Don't forget to post some photos after you add fish.