Tank Crack

[Nap]

Hi all, I have a three year old system that just developed a crack in it. It's a 100 gal pentagon (corner tank) and the crack is on the top support of the tank. Here are some pictures (yeah, i know it's dirty up there)
http://www.imagedump.com/index.cgi?pick=get&tp=252004
http://www.imagedump.com/index.cgi?pick=get&tp=252003

And this is the front of the system
http://www.imagedump.com/index.cgi?pick=get&tp=252005

I am wondering how I should go about fixing this. Will I need to get acrylic and epoxy? And if so which epoxy is safe? Also does anyone know where I can get some idiot proof instructions for the proceedure?
Thanks!
-Ian

[won digity]

You can look for a local plastic shop and ask for some "weld-on". I'm not quite sure what # weldon you'd need for a crack like that. But I'm sure if you explain your situation to them, they will be able to tell you which one to use and the best way to go about fixing the problem.

Epoxy could work, but is not a longterm solution. Weld-on kind of "melts" the acrylic together into a much stronger bond.

[Nap]

A plastic shop eh? Will look for one. Thanks for the reply

[pookstreet]

You can probably use Weld-on #3 or #4. #3 works much faster than #4.

[wobble123]

I would use a couple peices of acrylic and sandwich the crack between them and use weld-on to glue them in place. this will give the crack plenty of support.

[sportbiker29]

What your going to need to do is get a scrap piece of acrylic and put it over the crack just like you would patch a pair of pants. Putting solvent straight into the crack won't help. Use Weld-On 16 and apply it to the underside of the scrap. Once dry then lay down a bead of 16 around the scrap piece of acrylic. It won't look pretty but it will work! You can do this whole process with Weld-On 4 as well but it's a water thin solvent and 16 which is thicker is easier to use for a novice. Good luck and let us know how the repair comes out.

[Hawkdl2]

First you should clean the surface very well then use Weldon #3 or #4 and using a syringe like applicator (such as the syringes that come with a Salifert test kit) and allow the weldon to wick into the crack. If you can flex the crack open a tiny bit by pushing on the side of the tank you will insure a fairly good weld. The problem, however, is that the tank cracked for some reason suggesting that there is too much stress at that point. As suggested above, I would then weld a piece of acrylic over the crack. I would do the same to the other side of the tank too, even if it hasn;t cracked yet. You can use weldon #3 or #4 or the #16 as suggested above. all will work fine. Put some wieght on piece to make sure it forms a tight bond.

[Nap]

Actually the tank cracked because of my stupidity...I had been messing with the tank and had accidentally unplugged the hood fans. After about 5 hours I got home and turned on the fans. It was so hot in the hood that within five minutes of turning the fans back on the acrylic cracked. As you can see the crack hasn't pulled apart, so i am hoping there isn't too much stress on it.

As far as sealing it goes...what is the difference between 16 and 3 or 4? Is the 3 and 4 really liquid (like water?) while the 16 is gooey? Does it make a difference in how well it will hold? For the piece of acrylic how thick should it be? What happens if some of the acrylic weld gets into the tank? Should I take my critters out? The system is pretty full as you can see so I was hoping to just drain about half and patch it. Then refill after a couple hours or so. Is that gonna work?