Backfromthedead
Why would someone make this tank at 1/2 glass though? If I recall correctly the safety factor is at a 2.
Why did they do that? Simple: it was cheaper. Not better or easier or even adequate for long term. It was cheaper.
Unfortunately i cannot recommend a good solution for your tank as i believe the 1/2" glass is too thin for 72" length x30" height.
Yes ive heard all the excuses..."look at my glass calculator" or "its tempered glass". I dont care. My position is the glass bows, maybe not all at first, but surely and slightly outwards from the force of 30" water level, which eventually and inevitably leads to problems with the silicone. A glass tank should NEVER deflect outwards on ANY panel no matter what anyone tells you. Ive personally inspected multiple 220g 72x24x30 marineland and other similar glass tanks with 1/2" panels that fail on the vertical side seams after a few years of use. Theyre just not built to last imo. Im sure there are exceptions so please dont bombard me defending your tempered tank. These are simply my personal standards.
jjohnwm
is still around and always provides something i may have missed so maybe he'll know a better course.
Like i said im really not seeing the major bummer. If youre willing to take the risk for 6" of water or want to go with a differing opinion then good on ya. I just wont recommend a fix unless i KNOW it will be effective and long lasting. I cant just tell you want to hear because big tank failures can be costly and dangerous.
I've got nothing worth adding here. I made the mistake a year or so back of commenting in a thread about DIY plywood tank construction regarding glass thickness. That turned into a name-calling pissing match of sufficient magnitude that I just don't get involved with this topic anymore. I'm only posting now because you tagged me and I think ignoring it would be impolite.
I fully agree with
Backfromthedead
regarding glass thickness. I don't want to see glass deflection at all, and I don't care how many others want to pipe up with stories of their successes using the absolute thinnest materials they think they can get away with. This is the same mindset that asks for the absolute smallest tank for a given species of fish, or the absolute maximum number of fish that can be kept in a given tank, or...well, you get the idea. I am not interested in dancing that close to the edge of disaster.
I worked for an all-glass tank maker back when I was in high school, and he insisted on a safety factor of at least 4, and aimed for 4.5 or better. He never used cross braces, and rarely Euro-braces; he just used thicker, stronger glass with its attendant wider, stronger silicone bead. It was many years before I saw a tank with a crossbrace, and my first thought was that some cheapskate had tried to brace a tank so that he could get away with thinner glass. It was around that time as well that I saw a tank with a front glass bowed out when it was filled up. The guy said "Oh, yeah, that happens with all tanks. Nothing to worry about". Yeah, right...
Looking at that pic of the crossbrace failure, I can't help but wonder if the fault lies at least partially with cheap-ass bargain-grade silicone ("Kraken"?)...or
expired cheap-ass bargain-grade silicone...perhaps in combination with insufficient glass cleaning and preparation. It's impossible to overstate the importance of perfect cleaning of the mating glass surfaces before applying silicone. And cleaning the upper edge of the front panel, where the brace sits on top of it, is more challenging because the glass surface of the edge is not polished smooth like the sides. Any microscopic imperfections in the glass surface can and will hold contaminants that can and will mess up the seal.
And finally...your mention of possible seismic jiggling and wiggling makes my blood run cold. Just another layer of urgency regarding careful selection of quality materials and painstaking preparation.
