Discus Preperation

This is a tricky one. All the fish you have are torpedo shaped; discus are not. You can't go by the length (the standard way of calculating stocking levels). How big will the discus be when you buy them - babies, juveniles or adults?
You could try to estimate the mass, how much do your current fish weigh compared to the weight of the discus? Though even that is not perfect as 10 grams of discus will have a lighter bioload than 10 grams of assorted tetras and guppies.

Overfeeding your current stock should grow more filter bacteria. I think what I'd do in your situation is overfeed as you have been doing, then as soon as the other fish are gone and the discus in start to underfeed. Make sure you get out any uneaten food before getting the discus, maybe do a huge water change and clean a couple of days before. Thorough cleaning, especially on gravel, can kick up sediment which can cause ammonia/nitrite spikes, so doing it a couple of days early will allow the tank chance to settle down again.
And you'll already know about testing several times a day once you have the discus 

From what Peter, the owner, has said about the CC, it does take bioload into account. That's why it allows you to have more low-bioload fish than the 1" per gall guideline allows. However, Peter is not infallible and there could well be some errors in the CC which is why I always err on the side of caution.


Have you noticed that the new CC has slightly lower stocking guidelines than the old CC? Peter did respond to criticism when he set up the new forum.

I have tested my water this morning. I did PH and high PH, I always have had trouble getting an accurate reading because I seem to be too high for PH but too low for high PH. Again this morning the PH was blue (7.6) but the high PH was a light brown (7.4.)

I had exactly the same trouble as this.... so I ended up buying a Nutrafin wide-range pH tester which showed my pH to be a tad under 7.5. It only goes up in steps of 0.5 but I found it easy enough to work with. My KH is reasonably high so my water is bullet-proof, but I wanted to know what it was and didn't trust the API kit on this test.