They're in a 20 gallon long tank. I haven't been cleaning the tank on a weekly basis, but have considered starting. When I do clean the tank, I take everything out and clean the gravel and rocks and wipe the glass clean. If the water is low, I replace it and add Tetra Aquasafe respective to the amount of the new water that I put in. I replace the carbon in the filter when I do a tank cleaning, but I don't typically take the filter itself apart - I just wipe the outside of it . I dunno if pH test kits expire or not, but according to the one I have, the pH seems to be between 6.8 and 7.2. I have no test kits for ammonia or nitrates, and won't be able to make it to a pet store until this weekend.