OKCKitty said:
Well, in simple terms you may have to do daily water changes (3 times per week absolute minimum) for a while until all the good bacteria in the tank build up their numbers. Once you have plenty of good bacteria, which takes a few weeks, you can then just change the water once a week. If you keep up the regular water changes and change 25% of the water as needed (daily now, weekly later) you should be able to get through the teething troubles just fine.
As you will have read in the cycle posts, the 'bad' chemicals that build up in the tank which hurt the fish are ammonia, nitrite and nitate. The last of these, nitrate, is the best of the three and so we want the bacteria to turn all the ammonia and nitrite into nitrate and then we get rid of the nitrate with the weekly water change and keep the level down.
Ammonia builds up quickly in a new tank, but I find the good bacteria that eat it also build up reasonably quickly and should be in high enough numbers in a couple of weeks to eat it all and turn it into nitrite.
The bacteria that eat nitrite and turn it into 'better' nitrate seem to take longer to grow and it may take another 3 or 4 weeks to grow to sufficient numbers. But you can keep the nitrite levels safe for the fish as long as you don't have too many fish in the tank and you do the daily water changes while the bacteria build up. The bacteria live in the gravel and filter and any other surface, so changing the water won't really have any effect on them. Some sort of porus sponge media in the filter is a nice place for them to live. On your filter the biowheel is set up as a place for the bacteria to live as they like lots of oxygen.
Since you have a test kit, the main things to test for are ammonia and nitrite. If the tank has been up a couple of weeks then the ammonia is probably already very low. The nitrite is probably getting high. You just keep testing and when the nitrite gets low you can be confident the bacteria are getting in good numbers and you can ease off the water changes to weekly.
You can test the nitrate as well. but it should only go up when the nitrite goes down - although important you should check the water in the tap as it can be high in nitrate sometimes.
Honestly I wouldn't even worry too much about the ph just now unless your water is really soft. Test for the kH hardness if you can. If the water is hard or moderately hard then you should be fine. If the water is really soft then you may have to add something to the tank to make the water harder (you can easily buy this). If the water is too soft the pH (how acid the water is) can change up and down too easily and this is bad for the fish. Harder water can be more stable in pH, although obviously this all gets complicated...
All the advice you get will be an opinion based on whatever previous experiences the person has had, so there is a lot of variety. I am fairly new back into fish after a long absence, but at least have recently had to deal with these sorts of problems
