i will also look into the trickle filter... would that be in place of a sump? because im pretty set on building a sump.
So ... no that drilling the tank may be a possibility..... if i do have it drilled... where do i drill it? just the back?
I don't recommend a trickle filter in the conventional sense. A traditional trickle filter uses filter floss or bio-balls, both of which collect detritus from your tank and become nitrite/nitrate factories (it's one of them, but I can never keep the two straight). Instead, just load your sump up with live rock. The live rock is your filter. Live rock is the main filter in 90% of all salt tanks, so you'll fit right in.
As far as where to drill. It's up to you. If you don't mind installing an overflow wall, then feel free to drill into the bottom of the tank. Keep in mind though that many of the larger tanks are tempered on the bottom only, and you can't drill tempered glass. If you don't want to lose real-estate to the overflow wall, then drill in the back of the tank up high. Install a screen over the bulkhead and remember to keep it clean. Failure to do so equals a flood. The nice part about this design is that it relies only on gravity for draining, there is no siphon to worry about restarting.
Personally, if you go this route I'd add a second drain slightly higher than the first for use if/when the first one clogs. It's your emergency drain.
If you don't want to drill yourself, most glass shops will do it for you for $20-30 per hole.
If you decide to go with a siphon-over-the-back style overflow, as said above you MUST get one that will automatically restart after a power outage. Lifereef is a brand I used, and would recommend, for a decade before switching to a drilled tank. The only downside to a siphon overflow is that you have to periodically clean the U-tubes so the algae growth inside doesn't slow the flowrate too much. About every 3 months if you're using Metal Halide lights was what I found. Lower intensity lights would cause slower algae growth.
Personally, I'll never have a non-drilled tank again. I'm running a Herbie style overflow now and love it.
Lastly, no matter what setup you use, I highly recommend adding a float switch in your tank that is hooked up to your return pump. If the water level reaches some threshold, the switch turns off the return pump. This is a backup way to prevent a flood. Trust me, it works great, and has saved my marriage several times.
Just check the power rating on the floatswitch to make sure it can handle the current that the return pump is drawing. Depending on the current draw of your pump, if the float switch can't handle it you may need to add a relay. Do some searching online and you'll see what I mean.