nope, in fact I like bigger tanks. I have a 40 long that I used for a long time I just loved it now my main harem is in a 65 g. Just get a bigger UTH actually it is easier to get a proper heat gradient with a larger tank because you can put a decent sized UTH at one end and have a definent cool end.
:I am considering moving to a 30 gal. tank - 36" length. Is it more difficult to properly heat this long tank with an UTH than a 20 long? Thx!!! RR