You say that your gravel is almost new at this point..... did you clean/vacumn all of the gravel in your tank at once? You may have released a lot of nitrates if you cleaned everything at once in your tank, at least that's what I have read some place before. They said not to clean all of your gravel at once.
Also, why do you use ammo chips in your 330 filter? If the bio wheel is suppose to do it's job correctly, isn't it suppose to convert all of your ammonia correctly? I thought the bacteria on the bio-wheel uses ammonia from the tank as food, if your removing it before it gets to the bio wheel....then??? If your having ammonia spikes with a 6 year old established bio-wheel I think there's something else wrong.
Also, why do you use ammo chips in your 330 filter? If the bio wheel is suppose to do it's job correctly, isn't it suppose to convert all of your ammonia correctly? I thought the bacteria on the bio-wheel uses ammonia from the tank as food, if your removing it before it gets to the bio wheel....then??? If your having ammonia spikes with a 6 year old established bio-wheel I think there's something else wrong.