Overflows

i would have it drilled the hang on over flow boxes are not very safe it you do end up going that way put a lifter pump on it in case ya lose power and your syphon stops when the power come back on the pump will start the syphon for you

 

i think aquatic environments will drill the tank for you, if your afraid of breaking the glass.  for your second question, put a ball or gate valve on the return pump from your sump to control the flow rate from your sump

 

yeah they will killer for 45 bucks a hole. but they cant promise it wont break. plus he isnt sure if it is tempered or not.  And yeah you want to use a ball valve coming off your return pump.  a mag 9.5 is what I use on my 90, and i have to throttle that down some.

 

i have all my tank drilled and have never broke one yet its worth it to have it drilled Adam is 40.00 a hole sea of marvels in north liberty is 18.00 so it is worth the drive he has never broke a tank yet the chances of that think of glass braking are slim to none

 

he just messaged me, the bottom is tempered.

 

got to drill the back the only thing on a fish tank tempered is the bottoms

 

I agree with everyone drilling the back is probably the best way to go. But to answer you question about overflows. I used the CPR overflow with the aqualifer pump. I personally had no trouble with it. I would use the 1200 or 1500 gph for a 90g tank.
http://www.fosterandsmithaquatics.com/product/prod_display.cfm?pcatid=3642/prod_display.cfm?pcatid=3642

 

If you get a U-tube overflow and have your pump flow matched properly you won't have any problems. Physics is on your side.

 

Best HOB overflow is http://www.lifereef.com/siphon.html but is kinda $$