its normal for older braceless tanks to bow. when I started fishkeeping ( late 80's/early 90's) there were no tanks commonly available with center braces.
they were all braceless.
bowing to a slight degree was normal and expected. 1/2" bow over a 6 foot tank is typical of braceless tanks made with the thick glass they used to use.
my old 90 (purchased in 93) was braceless, had a slight bow as well, made with 1/2" glass.
so in terms of integrity, as long as the seals are good, you are fine. personally, I would rather have an 'old style' 125 made with 1/2" than a modern 125 made with only 3/8" but thats just me.
the main reason you might want to add a braced top is so that commonly available glass tops will fit.
the old braceless tanks had 3 peice tops (two end peices and a hinged middle peice) but you can't get them any more
you have to have one custom built.
they were all braceless.
bowing to a slight degree was normal and expected. 1/2" bow over a 6 foot tank is typical of braceless tanks made with the thick glass they used to use.
my old 90 (purchased in 93) was braceless, had a slight bow as well, made with 1/2" glass.
so in terms of integrity, as long as the seals are good, you are fine. personally, I would rather have an 'old style' 125 made with 1/2" than a modern 125 made with only 3/8" but thats just me.
the main reason you might want to add a braced top is so that commonly available glass tops will fit.
the old braceless tanks had 3 peice tops (two end peices and a hinged middle peice) but you can't get them any more
you have to have one custom built.
