South American Cichlid tank

Question
Do you use Python cleaners or any kind of siphons hooked directly to your tap H20.
I have been using the python system and its easy b/c there is no buckets. I add H20 treatment to make tap water safe, but someone told me your amonia can stay pretty high b/c eventhough you add the de-chlorinator it still has a chance to kill good bacteria in your tank.  Therefore, you have to restart a mini-cycle.  
It might make sense b/c my amonia levels are detectable....
Any opinions or suggestions on a safe way to do weekly water changes?
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Followup To

Question -
Hello!

Just wanted to know if you have any recomendations as what type of fish I can successfully mix with medium sized (and growing) american cichlids in my tank. (mainly for looks)  I was thinking large silver dollars, tinfoil barb, or something that was more of an open swimmer.

120 gallon setup
4"Jack Dempsey
6" Green Severum
3" Convict
6" Pleco (not in yet but soon to be transfered)
5" Red Snook

Would like a nice addition, for looks, not for food.....

Thanks!

Answer -
You really are going to have to stick with the moderately aggressive to aggressive fishes. Unfortunately with the size of the severums, they'd probably eat even a decently sized tinfoil barb as a nice snack. Silver dollars in large size would do just fine. In a tank with other moderate aggressors the Jack Dempseys would probably get along with raspboras, barbs, and gouramis. But the convicts (named aptly) will be a problem as they and the severums are the real aggressors in your tank.

You can keep a columbian shark (provided he's bigger than the convicts, of course) or one of his large-mouthed cousins. You can also keep talapias, gar, and bass in the tank but they are notoriously dirtier than their ciclid cousins. A cool addition would be a large butterfly fish as well, they hang around the surface of the water more often. Oscars if they are of a decent size can add a little variety.

Unfortunately, most other tetras and catfish are out of the questions as they have no way to hold their ground with the true ciclids. Ciclids have teeth - most other fishes do not.

I hope I helped you make a decision.

Answer
If your ammonia levels are still detectable either you are going through new tank syndrome or yes your tank is in the process of breaking down. The gravel vac is specifically designed to remove some bacteria that live underneath your gravel. Sometimes this bacteria can bloom out of control if there is too much of it and it will start to break down your tank, sometimes there is too little and the same will happen. This can boost your ammonia levels from time to time, as does fish waste, but as long as you do your water changes once a month you shouldn't have to worry about it. You can buy ammonia sponges which are just additions to media in your filter which may help. Throw out the regular sponge in your filter and start anew, and see if you need to replace your carbon insert. Carbon doesn't stay active indefinately. All of the above will also help keep the tank clean and make maintenance easy for you. Activated carbon will help filter out little amounts of ammonia at a time. Add a some aquarium salt to the water incase there is some stress to the fish. Chiclids like salt. If you use bio balls, just get rid of them. They do more harm than good in a freshwater tank. You may also want to add an air stone or two, which will also help your maintenance cause.

You should only need to do partial water chances once a month if your tank is established - too little bacteria is just as bad as too much.