You simply stop using one and start using the other; the only thing you need to do is to follow the instructions.
To be totally safe do not change all of the water at once; do partial water changes so the change of dechlorinator is gradual.
Most likely, they both contains the same basic chemicals, only in different concentration--the differences is mostly in ...
I don't know of any "good" worms.
If you've got worms in your tank it's a sign of over-feeding or inadequate filtration. So figuring out the cause is key to keeping them from coming back.
This particular specimen looks flat and rusty colored to me, which would be indicative of the "bad" kind of Planaria. Detritus worms would be long and ...
Your Fish Have "New Tank Syndrome"
Adding fish to an un-cycled aquarium will always result in death unless the proper chemicals/solutions are administered properly (outlined below).
Other causes include:
Over-feeding: You should only put as much as they can finish in 1 minute
Adding water that is not conditioned
Illness, particularly something ...
At your current situation, I guess that your fish do not have any chance to survive long, so forget about them. I recommend the following:
Set up a small environment for the surviving fish (if you till have them). A bigger jar should be fine. change the water every day with clean un-chlorinated water.
The easiest (but more expensive) is to just throw away ...