Long time no see guys. After the tank episode, I'm finaly sorted out with a brand new 225L (about 57 gal) tank. Theoreticaly this gives me room for two more teles, but I will restrain myself The girls have recovered well and are enjoying the new tank. I cycled it using media from the pond.
But I'm here to post about checking your tanks in the hope it can be prevented from happening again.
I would urge you to check your tanks. In the last month at the aquarist society here their have been 5 members tanks bust. After a thorough inspection of my old 150L (38gal) tank, I found one of the glass struts to be weakened and not connected correctly, hence not distributing the pressure as they should, which explains the dead centre split. These struts are the glass that braces the top of the tank. In some tanks, their are metal or plastic crossbars and frames etc instead on the top. Either way, I would suggest to inspect whatever bracing system your tank has semi regularly, as inadequate bracing seems to have been the cause for he 5 tank blowouts. If your tank is a flat glass tank and is starting to bow out from the water pressure, it either needs better bracing or replacing, depending on the age of the tank. Older, thicker glassed tanks or tanks in a re-enforced frame (NOT the decorative side strips on your average tank, but an actual frame to support the whole tank) may not be strutted, but should still get a check every now and then, as they rely on frame and thickness to stand the pressure, rather then distribution. Tanks over 2 feet generally need some kind of re-enforcement or pressure distribution in their construction, whether it be frames or struts.
Glass struts are what is used to hold coverglass in place (unless you sit it on the tank)
Remember, their distributing weight and easing pressure, so keep them in good nick to prevent a blowout like what happened to me 40gal of water on the floor is not a great scenario at all!
Signs of a tank not distributing pressure correctly are (assuming a standard rectangular tank)
-Bowing of the glass
-Glass 'chinking' noises at night (microcracking of glass)
-Weak or moveable struts or crossbars. REPLACE or REPAIR if they show any weakness.
-ANY crack, no matter how small. Above the waterline may be alright in some cases.
Keep your tanks in the best condition and prevent blowouts by...
-Keeping a foam underlay under them to stop a bump in the stand surface causing a crack
-Use the stand designed for that tank. It's made to distribute the weight of that modle in the most efficient way. If impossible, use a very sturdy surface.
-Inspect it semi regularly for chips, nicks or any bowing.
-Keep your silicon in good nick, replace it if needed. It stops leaks!
Happy fishkeeping guys! Hopefully this is of some use to someone!