[Festus2]

In what way was this last flushing process different from the previous times? You said that the "last one did not go down well". (????) Can you be more specific? More information would be helpful to us so we can offer some suggestions.

In addition to using Dawn or some other detergent, I use Calgon (a water softener) and plenty of water. Calgon help keeps the sides of tanks "slippery" so crud doesn't stick to it as easily.

I wouldn't use bleach - it would be hard on the toilet and other seals in the system.