I got a 55g online for cheap and was in the process of cleaning the tank when I noticed that nothing worked for getting rid of the water stains. And I used everything. CLR, acetone, vinegar, vinegar and baking soda, steel wool, razor blades, nothing did a danm thing so I said screw it.

I took the front piece of glass off and cut a new piece for the front out of god knows how old a piece of glass I found in some old ladies barn. It had at least 30 years of grime on it but with a little vinegar it came off with out a struggle and now I have a crystal clear front panel now.
Taking a piece of glass out of your tank seems like it would be really hard but it is actually pretty easy. First I took my dremmel tool and cut the topper into 4 pieces. I learned that a serrated knife works even better. (No flying chunks of molten plastic hitting you in the face...) Then I started to peel the plastic off the glass. I had to start by bending the outside part until it broke exposing the silicone that is actually holding it onto the glass. Then I used a floppy knife to get in there and separate the glass from the silicone.

Once that was done I cleaned it all up with a razor. I ended up with a pile of broken plastic and silicone. Obviously the top frame is going to be useless after all this. This is ok. Im going to make a new top out of oak or maple. The bottom frame came off with out any problems. I am keeping this for a jig when I silicone it back together.
By far the hardest part was separating the bottom part of the glass. Who ever owned it before me used a gang-ton of sealant and that stuff is hard. I just used a serrated bread knife and sawed my way across the bottom. It took some elbow grease but it came off!

Cutting 1/4" glass is a bit more difficult than double strength 1/8". After you score the glass you have to tap it along the score line from the bottom of the glass. This can cause a few problems though. First the edge is not smooth so you have to go back and break off the burrs and grind off all the rough spots with a smooth rock and then with 80 grit sandpaper. Second because of the thickness it is hard to keep the break along the score line at the end of the cut. On my piece of glass i ended up with a 1/8th inch overhang and had to grind it back down which can take time.
Now with a fresh new piece of glass I will silicone it all back in place and re-frame it. I will post more pics as I go along.
I am probably going to have this tank at my job. My boss really likes the other one I did and This would fit perfectly in the main pipe room! I am going for the same kind of primitive plant tank. I just need to figure out what to put in it. I could go the route of darts but Im not sure I want to go through all the hassle of doing a FB and building a waterfall and all the filters. Eh... No clue I know its going to have a full background. Not sure how I'm going to do this. Im not really a huge fan of greatstuff backgrounds. I want to go for as realistic as possible.