Bacteria in a bottle is always a hit or miss
. That is why most ppl, myself included, think of it as a waste of money and a way for pet stores to make money.
You are right on track for cycling your tank. To reduce the nitrITE toxicity to your fish, add 1 tablespoon of salt per 5 gallons of water. Table salt will suffice, dissolve it before putting it in the tank, add it slowly.
You may already know this..but i'll post it anyways. When you cycle a tank, your ammonia will spike first. After the bacteria that consumes ammonia starts to develop you will see a spike in nitrITES. When the bacteria colony that consumes the ammonia is fully developed you will get a 0 reading for ammonia, however your colony of bacteria that consumes nitrITES is still growing to consume the by product of the consumption of ammonia. Right now you should be testing positive for some nitrATES. After the bacteria that consume your nitrITES is completely developed, you will be left with 0 ammonia, 0 nitrITES, and some nitrATES, your cycle will be complete.
My reccomendation is to have patience, take care to keep your water parameters (ammonia and trites) at .25 or below the best that you can, and let nature take it's course. Stop adding the bacteria in a bottle that promises to instantly cycle your tank, and if you can get some more bacteria from your lfs
, go for it. Remember, you already have the bacteria in your tank, in other words you have seeded it, you now have to wait for the bacteria colony to grow to full size to accomadate the bio load