Questions:
Would this be too much pressure for a reactor?

No.

Is there such thing as using too
strong of a pump?

Within reason, no. Not in your case.

How do you mount the internal or external reactor?
It can simply hang into the tank from above for the internal, the
external can hang vertically off the side of the tank and have a
return coming up from the bottom.

What diameter PVC or gravel vac should I use.

2 inches should do it, about 12" for the external.
Internal, you might want to use clear acrylic 2" dia and match it up
with some PVC fittings to connect with the spliced line.

Could some1 provide a link that has detailed pictures and tips 4 me?

DIY.

Some folks have DIY CO2 units for Fluvals, Ehiems etc, but few sites
will show you what you are trying to do.

Regards,
Tom Barr'


Thanks!

N8