Pat Mary- I am short, under 5'5" and I have tanks that are deep. 45 gal is just under 24 inches. My 150 is about 28 and the 125 is also about 24.
Two thoughts here. To work in deep tanks you need a steps ladder which allows you to be above the rim. How deep you can reach is easy to figure. Stick a tape measure in your armpit and measure the distance to your palm. That is about the limits of one's reach when started from above a tank rim.
Next, I use these when I cannot reach http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=24133