Already some great suggestion has been provide. It also help me a lot from those meaningful concept.
Agree try a dif test. That ammonia is very high.I would also stop cleaning the filter until your tank is cycled. That's where all the beneficial bacteria is. With an ammonia of 8 I would think your fish would be dead. What kind of test are you using? Are you sure it's good?
10-25% water changes will have almost no effect on the ammonia levels; it's simple mathematics. The reason for the problem is the pH - it's too low for the bacteria to efficiently multiply. Do not suddenly raise it; with 8ppm ammonia a pH of 7 would be almost instant death for the fish.
Get a KH test kit. You'll probably find KH is very low. Then do a series of water changes to get the ammonia down to 0.25 ppm or less. Ignore anyone telling you water changes will slow the cycle; it's an old myth.
Once it's down, you can then start to raise the KH using sodium bicarb. When it gets to around 4 degrees, the pH will have risen above 7 and the bacterial inhibition will be much reduced. Keep KH at 4 degrees during the cycling process and you'll be done in a couple of weeks or so.
All good info: also:
by doing water changes, you are not removing bacteria- they reside in the filter, gravel, decorations- change the water immediately, as this is the only way to remove nitrite and ammonia.
i seem to have no problem quick cycling mine. Plants, a bit of water/bacteria from another tank, and filter running, then add some fish food in, its organic matter, it'll break down,