Cadlights overflow cracking around return outlets??

[CMO]

Anyone had their overflow crack like this around their return outlets? It's happening on all 3 of mine and I'm at a bit of a loss since they really aren't that tight. I placed the gaskets on the back of the overflow wall like shown in the top view photo. Is this right? Should I also add gaskets to the front of the overflow? The cracking isn't terrible right now but I'm worried about long run effects and having them continue to get larger. Thinking about gluing 1/8 acrylic plates over the outlets to strengthen the area and bond the cracks to prevent further spread. Any thoughts?

 

[flat6guy]

What kind of light is over the tank? Metal halides have been known to age plastic braces and causes them to crack. Are the returns vibrating or was the plumbing putting stress on things when assembling? I like your idea of adding a brace. One suggestion would be to use an 1/8” drill bit at the end of the crack. This will help end it and might stop it from spreading. Cracks continue in a line. Rounding them off help stop them. Common practice in the aviation industry.

 

[CMO]

I have T5 and LED lighting. There is flexible tubing running up from the bottom to the outlets which I had to bend slightly to align with the outlets. I also do not have the return pipe glued so maybe there is some pressure pushing up from the return flow? Seems like most people do not glue return fitting inside the overflow so i have a hard time believing this could be the cause. Everything was pre-cut and assembled so I assumed this minimal amount of strain from the flexible tubing was acceptable. Maybe I'll try and resize things to reduce strain in addition to the reinforcements. Thanks

 

[xjiang7]

Mine has a single crack from over turning when I first installed it. I fixed it with some super glue

 

[Jeepguy242]

What kind of light is over the tank? Metal halides have been known to age plastic braces and causes them to crack. Are the returns vibrating or was the plumbing putting stress on things when assembling? I like your idea of adding a brace. One suggestion would be to use an 1/8” drill bit at the end of the crack. This will help end it and might stop it from spreading. Cracks continue in a line. Rounding them off help stop them. Common practice in the aviation industry.

It’s called stop drilling if you want to look it up.

You have to make sure you get the end of the crack or it will continue through the hole