replacing glass in a tank

[Katfsh]

has anyone ever tried to replase a pane in a tank. I have a 20 gal tall that the bottom has cracked in and was wondering if I could just replace it. I know a new tank is only 50 bucks but still a peice of glass at lowes couldnt be that much. what type of silicone?

katfsh

 

[Anonymous]

I don't think lowes carries the thickness of glass needed. I know on my 20high the glass is 1/4"

I used perfecto brand silicon to built my 58 gallon.

And if you look around, you should be able to get that tank for $30.

B

 

[Anonymous]

Not worth it for that size of tank, since you need to stripes the silicon out and redo all the seams, and after spending $10 on the glass, $10 on the silicon, and 4 hours of work, you may end up with a leaking tank.

Sorry that the tone is against the philosophy of DIY, but just so you know what to expect.

However, it is a great project if you want to practice your tank building skill on...

 

[wade1]

In a tank that small, I've seen people replace the entire panel and leave the cracked pane in place. Just silicon (without air bubbles) the new pane underneath or on top of the old one well and it should hold up - of course, that only works with small volume tanks or tanks with simple cracks.

 

[Katfsh]

well this was no simple crack! Got to the shop this morning not a lot going on so I went to work at taking the bottom out after about an hour I had it out all the silicon off, I even went as far as removing all of the silicon from the inside corners the whole height of the tank. so basically the only silicon left on the tank is where that edges of glass is butted together, and on the top plastic peice. I called and got the peice of glass cut ($9.00) and they didnt have the right sized bit to drill the glass, so i ordered a bit off of the net.
Next question I have is there any problem drilling the hole once the tank is together or should i drill it before I put it back together with the glass flat on a peice of plywood?
what different types of silicon are ok to use?
and how long should the silicon set up before filling with water to test for leaks.

 

[Anonymous]

I would drill before assemble the tank. You won't have to remove the silocon and start over again if the drilling crack the glass (yes, I am a pessimist)

Pretty much any quality silicon that does not have mildew-resistant or fungicide or bactericide are fine.

I would wait at least a day or two for the silicon to cure.

 

[Katfsh]

ok is there any thing that I should wipe the glass down with first?
also how hard is it to cut acrylic i am thinking of making a overflow box
can you use a table saw?
i asked the local glass shop if they had any black acrylic and he said yeah i have some black plexiglass, could he mistaken and it be acrylic, will plexiglass work as a overflow.

katfsh

 

[Anonymous]

Plexiglass == acrylic, among many other brand names.

You can cut acrylic with table saw, but unless you have the right blade/feedrate, it can chip pretty badly. It may work, just need to test with a scrap first. It is very easy to cut/scratch/bend/drill, similar to wood.

for glass, some use acetone, IIRC, to pretreat before silicon.

 

[brandonberry]

The silicone tubes say to use isopropyl alcohol to clean the glass prior to use. I usually first clean the entire tank with vinegar and water and then clean the edges to be siliconed with the alcohol. I buy the 91% stuff because it seems to cut through any residue. You did the right thing removing the silicone from all the inside corners. It tends to deteriorate over time and needs replacing every few years anyway. Also new silicone will not bond with old silicone well, and if you had left it you may have had a leak where the 2 joined together. Make sure you scrape all the residue from the old silicone off in order to get a new bond with the new silicone. That last bit is hard to remove, but needs to be off to make the bond strong. Use masking tape to outline the edge where you will spread the silicone to get a nice clean edge like a new tank has. Once you have applied all the silicone, remove the tape slowly. Do not allow the silicone to start to dry before removing the tape or you will have a mess. If a little smears, you can always come back later after it is dry and clean it up with a razor blade.

Good Luck

 

[Mthompson]

Hey Katfish,

When cutting acrylic with a tablesaw, you should reverse the blade (a smooth finish plywood blade, with small teeth preferably) and cut slowly while using a spray bottle filled with water to spray on the blade (right where it is cutting and along the part touching the edge of the new cut). I also like to adjust the height of the saw so that the teeth just cut through the thickness of the acrylic.

This method done right will give you a clean cut with no chips, and the water cools the acrylic so that is will not melt together (it will form a paste of moist acrylic 'sawdust').

Let me know if this is clear enough, but if not, you can do a google search for cutting acrylic and they may explain it better. Plus that is where I learned the method from.

Miles