1. Frank mentioned that not only should the tank be dry but also very clean. Often this meant wiping it down with rubbing alcohol in a very well ventilated place (outside?) He had no qualms about bonding glass to glass. He would suggest the hobby rumor that glass doesn't bond well to glass is misinformation.

2. The silicone sealant should be specifically designated as safe for aquariums. It should say so on the tube. DAP makes such sealant. I think there is another manufacturer, outside of the aquarium subculture, that does too. A lot of the others have arsenic or something else to kill the bacteria. I don't think I ever messed up on that source of mystery deaths. ;)

I do remember the account of a lady proprietor of a pet shop. She had redone her bathroom and was complaining of green seals in her shower. I meekly asked her if she was using some aquarium sealant she had gotten inexpensively through her business. :0

3. Frank then mentioned that the best silicone seal was a very thin one. He noted that lots of tanks had thin seals. We assume that they are being cheap. He felt though that the thin seal would cure and hold the best. At least that had worked with some other significant applications.

4. Any time someone put more than 1/4th inch of silicone on, it was too thick for it to the seal and bond properly. It was too hard for the water vapor to permeate past all of those other solidifying silicon molecules and there would be an inherent weakness to that seal. (Oh me of little faith, who has been smearing that stuff on too heavily!)

5. He also noted that the liquid silicone would become a solid basically when the silicone molecule bonded with a molecule of water - but only as water vapor. The process would stop if the tank were filled with water. Also the relative humidity needs to be pretty substantial. In desert areas where vehicle parts need siliconing and the humidity is way down, about the only way to do it is to silicone the part, put it on pavement under a box. A pan of water should also be put under that box. The heat would evaporate water, the box would hold enough humidity in that the silicone would begin to solidify.

6. In a day the silicon is sealing the tank pretty well, BUT the silicon has not effectively bonded with the two or three parts of glass.

7. Aside from some other chemical processes going on (he explained some of the chemistry but realized he would lose us quickly if he got too involved), he then floored me by suggesting that the bond between the pieces of glass would not be at its strongest until it had sat for a week! Oh boy! No wonder those tanks didn't hold water as long as they should have!

As a person, who is so impatient that he stands in front of a microwave and scream FASTER, I am really guilty of not properly sealing tanks or of waiting as long as I should have, even during hot summer days, before filling an allegedly repaired tank.

In the spirit of all Cubs fans (a mantra formerly chanted by Red Sox fans), "Next year will be different."

By the way, a crack in a small tank can be "fixed"  or at least dealt with by cleaning it as above and siliconing a piece of glass over the crack. If one has been in the hobby some years, there are pieces of tanks around. I would not try that with a large tank.

And I would aim the bad side away from traffic both for safety's sake and because those patches are ugly as sin. They can become sanctuaries for algae if not siliconed at the edges.

Oh! We are getting several windows changed out of our house sometime this winter. Probably will spend on heating, during the process, what we saved on off-season window deals. The fish room windows get replaced next summer. ;)

If anyone in Chicago-land wants to try their hand at making 2-3-4-5 gallon tanks, they are welcomed to the glass, but I need to know to save the glass. It is 50 years old, flat, but probably more brittle than new glass.

You would be wise to take that glass to a glasscutter and have them cut pieces to your specifications. If they have a gizmo to "sand" the edges of the cut glass, so it doesn't cut you, it probably is worth it. You wouldn't have to try "emeryclothing" it (with leather gloves on) to dull the edges.

You may find it is cheaper to buy 10-gallon tanks. But making one's own custom tanks is gratifying and may have design advantages when setting up a tank collection.