API Master test kit

Dear oh dear Mary,
And there was me telling you keeping Fish was easy...

Honestly it is, you're just still having teething problems, that's all.

I would suggest a 20-25% change each day until the Nitrites/Nitrates come down and you needn't 'hoover' your gravel daily unless it really needs it.
I don't use the StressZyme myself but you certainly will do no harm by adding it each change.

I'm not familiar with Juwel filter pads but I have heard it suggested to change the Carbon one as if the Carbon becomes saturated with the chemicals it's there to remove they will start to 'leach' back into the tank water, but once a week is, I feel, a bit over the top, I would think once a month might be more advisable. You tell us you haven't changed them, but have you washed them out? And, you probably know this, but you should never wash out the media in tap water, the Chlorine in it will almost certainly kill off your bacteria, always use some of the water you are taking out when doing the water change, this will be 'just right'.
Someone else will have to tell you which colour is which but even so, you shouldn't be chaning or even cleaning your filter media every week, it honestly only needs attention when the water flowing out appreciably lessens, if you are(?) cleaning the media weekly you are 'washing away' the beneficial bacteria you are trying to propagate for the whole tank cycling process.
I hope your fish will be alright, please let us know.

John
ps, was this a new 'in date' Test Kit? Sometimes results can be a little 'hazy' when they get past their date.