Im not adding any fish yet as know i have to let the filter and water settle etc. Im not adding ammonia to my tank, my parents had tropical fish tanks for years when i was growing up and they never did that. They would set the tank up and wait a week putting the tap water conditioner in and bits of fish food in for the filter to work and turning heater up to 30c and keeping the light on so bacteria builds quicker with the heat and then wait a second week and turn the heater to correct temp before gradually buying fish.
The reason it worked is that the fish food decomposed into ............ ta-da ..... ammonia!
There's no reason why you can't do it with fish food, it's just a bit hit & miss as to when the filter is ready. The theory with cycling with bottled ammonia is that when the filter is fully cycled, you can fully stock your tank in one go, rather than adding bit by bit. I think waiting only a couple of weeks with fish food is probably too short to get decent bacterial growth.
Yes, you have been adding ammonia to the water previously, as
the_lock_man says
The other problem with fish food is that it is more expensive than bottled ammonia, takes time to start releasing ammonia and your tank will need a very big clean to remove the rotting food before fish are added.
In the first week (before adding dechlorinator and ammonia source) nothing happens, so you may as well skip it.
The lights won't help the bacteria grow, but the heat will as you say.. on the other hand, ammonia and light encourage algae growth, so it's better to just let the heater keep the water warm and leave the light off.
And yes, one week of ammonia in the water isn't really enough for anything significant to happen. Usually, it takes 7-10 days for bacteria to grow enough to start processing ammonia in significant numbers, and another 2-4 weeks more to multiply to sustain a full stock (but there's no need to wait that long if you aren't planning for full stock to start with).
They never had a problem or any fish die so surely i will follow that route and not have a problem either
Ammonia and nitrite (in small quantities) will harm the fish in such a way that they will be more susceptible to diseases later on in life and will have a significantly reduced life span. So it is not surprising that if the fish were exposed to ammonia, that the effects would not have been visible immediately.. unless you're saying that the fish are still alive and have never suffered from any disease at all?
Surely, it is better to not expose your fish to toxins, now that you know better, instead of playing a guessing game with their lives and blindly hoping that it won't affect them?
S lol 
