How much weight can a tank rim handle?

[yanetterer]

Is there any information on how much weight the rim of a tank can handle? I'm thinking specifically in regards to clamp-on style lighting. I have had a pair of Kessil A160WEs with the arm mounts on a rimmed tank for years without issue, but I was thinking of adding some more light. Which got me thinking about just how much weight the tank could safely hold. Some of the larger fixtures have mounting arm options and that looks like that could a lot of weight being applied at a weird angle.

I've seen plenty of tanks run for years with clamp-on lights and I remember seeing one on here that had a couple of Kessils mounted to a T5 hybrid fixture using only the Kessil arms, which sounds like a lot of weight for the small mounting points so I'm curious just how safe something like that would be in the long run.

 

[Gtinnel]

I can’t answer your question, but many years ago I had a cheap rimmed 75 gallon tank and I had a huge wooden canopy that weighed a lot sitting on it without issue. Although to be fair that does spread the weight out over the entire top of the tank evenly.
I’ve always worried about the twisting force from single arm mounts.

 

[vetteguy53081]

Is there any information on how much weight the rim of a tank can handle? I'm thinking specifically in regards to clamp-on style lighting. I have had a pair of Kessil A160WEs with the arm mounts on a rimmed tank for years without issue, but I was thinking of adding some more light. Which got me thinking about just how much weight the tank could safely hold. Some of the larger fixtures have mounting arm options and that looks like that could a lot of weight being applied at a weird angle.

I've seen plenty of tanks run for years with clamp-on lights and I remember seeing one on here that had a couple of Kessils mounted to a T5 hybrid fixture using only the Kessil arms, which sounds like a lot of weight for the small mounting points so I'm curious just how safe something like that would be in the long run.

Its not a matter of weight but weight distribution and as stated by Gtinnel, they can handle I believe the old rule was equivalent to tank weight . Bowing is biggest risk but lessened with a typical rectangular tank