I havea 29 gallon AGA with 2x 55 watt retrofit PC and a remora aqua C skimmer. I would really like to upgrade it to a 33L because I like the length you get and my 29 has a lot of scratches on it from the previous owner being a genius. How much would this cost and could I keep my same lighting? (I could do 2x 65 watt with the same ballast) Would it put a lot of stress on my system because of the additional sand that needs to be added?

You are upgrading from a 30 to a 48" tank. Even with 65W bulbs, I'd recommend a new fixture. Sure the old one would work as well as it did before (maybe better because the tank isn't as tall).

If your tank has been setup for awhile, then disturbing the sand bed can cause problems. You could replace your sand bed (just cure the new sand ahead of time). I'd save a couple of cups of the old sand to seed the new bed. However, if the current bed is pretty new, I'd add the new (pre-cured) sand on the bottom and place the old sand on top of that.

It is a five year old sand bed but it got moved about 3 months ago. It looked like there was a whole bunch of dirt/silt in i so I rinsed it out in a 5 gal bucket a bunch. There are slitt a bunch of mini stars in it. I dont't know if this defines a "new" sand bed But no matter what if I upgrade I will have to get more sand because of the greater surface area.