well in a 30 high, there is one thing to worry about, gas exchange, see the larger the surface area of the water more oxygen and other benefitial (no spell check
) gasses can make it into the water, but in a 30 high the surface area of water is smaller allowing less gas exchange, but there is a way to help this problem, take a pump or a powerhead and point it towards the surface, not only will that aid in gas exchange, it will also stop a "slick" from apearing on the surface allowing your it to remain suspended and eventually be taken care of by your filter, MHO...... also i suggest using a sump for the filter,.....the bigger the better......also the lighting, you will need more powerful lights on this tank because of how deep the water is, so temperature will prolly rise unless you keep the lights some distance off of the top......good luck...
~Rankin