Thanks for the additional advice Byron. I read 2 weeks somewhere, but I'll definitely quarantine for 4-5 weeks then.This is good news all around.
If you are quarantining new fish, make it 4 weeks or even 5. There is much that you won't see with 2 weeks, believe me. Ich is a minor issue, and usually that turns up within 2 weeks, but these days there are several protozoan around and these can take longer.
If I have any regrets it's that I didn't quarantine new fish before, and that I didn't know to just go straight to the Coppersafe treatment instead of trying the heat treatment method and killing some of our beloved fish that may not have died otherwise (hard to say really). Oh well, you live and learn. At least I'll know better the next time around.
My next question is about this tank moving forward. I have two balas remaining, one looks really good, and one looks really bad. The balas may have been a mistake from the beginning considering their eventual size (something I knew going in but was reassured that it wouldn't be a problem by my LFS with a tank this size). I was also assured that the Pictus Cats I have are the 6" max size variety, so I hope that holds true. That being said, I'd like to limit the fish in this aquarium to what I would consider medium size semi-aggressive fish in the 4-6" range when mature. Will one or two Bala Sharks do well long term, or should I return them to my LFS once I sort out the tank issues? Don't get me wrong, I do love the Balas, but I realize now that even a 125 gallon won't be enough to support a full school of Balas at maturity along with the other fish that I have in the tank at this point.
Also, I must say that I've read and followed the advice in many of your posts on here prior to joining Byron (especially the ones regarding plants and lighting), so I trust that you won't lead me astray.
Btw, I've just uploaded my two tanks and a few pics for any of you that might be interested.