Also do you guys think silicone would work?
Try the silicone ... I done that in the past , and the silicone worked fine.. . Epoxy would be over kill...
Your looking to buy all these products that may or may not work to a tank that is not even up and running yet. Just redo the pipes. What's it going to cost 15 bucks? If it was a tank with a leak that you needed to drain all the way because of a leak I would say try all those ways but its a new tank that you can just shut down with no problem.
If you want to keep a clean look just get clear primer and wipe your connections after gluing. There comes a point where trying to be as neat as possible causes problems like this. The purple primer is just there for construction jobs where the work will be inspected since it's visible at a cursory glance. We never use purple on any of our work. Don't use silicone to fill the gap, it's just a patch and isn't going to be a permanent fix. Your best bet besides rebuilding the section is to use more cement or epoxy.
When, if using layers of PVC cement, do not use primer as it will strip some cement.
I would also use more cement when you do your plumbing from now on. I use enough to where a good amount squishes out of the joint and catch it in a small towel and then wipe the joint to where the excess is wiped away and the gap is filled with the cement.
Good luck.
+1 on using more cement. I've always done the same, a friend of my mine that happens to be an installer told me to always use a lot of cement to the point that it gushes out, then wipe it off. I never use primer though, I don't like the purple color, I sand the inside and outside of the PVC. Never had a problem.
Do you use anything to deburr your cuts? Might also be the reason you had a leak.
Stop beating around the bush. Replace it. Anything you will do other than that is a patch job. Don't want to temporarily fix it then come home from vacation one day and find a mess. I know it would be on my mind constantly if I didn't just replace it. $80 now will save you hundreds in headaches later.