Nitrite and Ammonia to high

Question
QUESTION: I have a 75 Gal tank had it for 4 weeks i understand the cycle of the tank with the highs and lows but am i suppose to change part of the water every day or not until it is cycled. i have 4 fish 1 Rainbow shark 2 trichogaster (Blue Gourami ) i think .and another type of shark that looks like a catfish.The rainbow shark i have has since day one  all the other fish i had died, the other 3 i have had about 2 weeks.I have bought books about problem solving but it does not tell me when to keep changing the water for safe levels, i just don't want more fish to die.last night i did about a 30% water change and cleaned the sponge filter in the old water that i emptied,but did not clean anything else.i Have a good filter system i have a Fluval 405 plus a under gravel fillter.The reason i did a 30% water change is i put in a ammo lock and it made the water really cloudy,now its not,but the readings still say high.Can you help me..janet

ANSWER: I would not worry too much about the cycling, since it has been up for a while it probably is done cycling and is just building up the waste. Have you cleaned anything in the time it has been up or just that once? If so, you just need to wait one day and do another water change of about 20%, and keep doing that every other day until the ammonia is gone. Also, it would help the process if you get some healthy live plants, they help to remove waste. Also, some bottom feeders like snails and algae eaters. Also, just to be sure put your ammonia reader in some other water to make sure it is working correctly. I hope I have helped you some. Let me know if you need any more help.


---------- FOLLOW-UP ----------

QUESTION: Hi, no i have not cleaned the filter only once yesterday,and i have not cleaned the carbon or any of the other stuff that's in the filter,i have semi cleaned the gravel when i have done water changes,but thinking maybe i should do a good clean of the gravel with tomorrows water change what do you think? Also do you think its a good idea to remove the under gravel filter and leave it out? I also do have living plants..I removed my ammonia reader and put it in my other tank and it went to safe.So it's working good.

Answer
Chances are the problem is the waste build up from not cleaning it. You should do a good cleaning of the gravel and the filter with you water change. Replace the filter media completely. Its a good idea to leave the undergravel filter as it probably helped keep the ammonia from not skyrocking. Just do a big clean and hopefully that will begin to fix it. Also good you have the plants, keep those and perhaps add more. Let me know if you need more help.