I repair and rebuild tanks and the short answer is yes it can be done. Note: There are no advantages to fixing a 30 gallon since you can buy one new at petco for $30 when they do the buck a gallon sale.
I have never seen petco sell anything besides 10g, 20L, 20h. 29G. 40B & 55G.
and they charge tax for the full retail so for about $30 @ a dpg sale you are limited to 20 gallons.
since the OP has most of the materials, and if its done right & tested .it should work out.
Hello everyone, and thanks again for all the advice and replies. A little bird told me to keep an eye out after Christmas for the 1$ per gallon sale, and sure enough December 28th I went in and bought myself a brand new 29 Gallon marked for $29 with a 25% off cupon, needless to say it was a great deal.
However, I also went ahead and took a gamble with my 30 Gallon. I put very thick beads along the cracklines themselves, removed and replaced the silicone on all edges, heavily siliconed the sides of a 10 gallon tank to the top and bottom of the tank on and around the crack area, and then cut some insulation foam to the proper size and placed it along the entire underside of the tank. I was very nervous while filling the tank with substrate and the hardscape, but here I am a few weeks later and the tank has been up and running just fine, I've been keeping an eye on the cracks and marked them initially with pieces of tape and a marker (obviously externally) and also took pictures, and none of them have spread or gotten any bigger. I know I was takin a big risk but it seems to have worked great and my girlfriend loves the tank. I'll post pictures soon but I just wanted to let everyone know that as of right now, the repairs worked very well.
I know it's not ideal, but if anyone finds themselves in a similar situation and cannot afford to replace the entire tank I think if done properly this is a viable option (While still extremely risky)