From the previous thread, it sounds like you had a pH of 5 (which is pretty acidic for an aquarium). You are also testing around .5-1ppm for ammonia.
When you say you cleaned your filter...does that mean you just rinsed it...or did you "clean" it (which destroys most/all of the good bacteria)?
What are your tap water parameters?
edit:
My first instinct is that you are adding tap water to replace water that has evaporated and causing a toxic buildup of something. Only ro/di or distilled water should be used to replace evaporated water.
The easier method is to just do water changes and replace normal water. It is common to do 25-50% water changes to eliminate any build ups.
When you say you cleaned your filter...does that mean you just rinsed it...or did you "clean" it (which destroys most/all of the good bacteria)?
What are your tap water parameters?
edit:
My first instinct is that you are adding tap water to replace water that has evaporated and causing a toxic buildup of something. Only ro/di or distilled water should be used to replace evaporated water.
The easier method is to just do water changes and replace normal water. It is common to do 25-50% water changes to eliminate any build ups.