Hey Steven told you about the PBT
I would keep it in the 7gal for at least 2 weeks or maybe for a month before moving it back into the other tank. You also want to make sure that there isn't anything in the main tank or any other fish have some thing. Don't want to PBT to get infected again.
By the way I just upgrade to the T-5 lights, got 6 bulbs, just haven't placed it on the tank yet. I'm going to be selling the 2 bulb retro, Ice-Cap Ballasts, soon. That should help with the growth in my tank. I just also got rid on my cyano problem using Chemi-Clean.
Michael