hello to you all this is my first post on mfk my q is i am thinking of buying a 150 gallon tank with bulk heads already pre drilled but not sure if to put them at the top or bottom i want to put in a sump under my tank also how do i prevent syphon back if anything goes wrong like power outage or pump failure also do i just use the bulk heads or would it be better to extend the bulk head internal outflow to more the middle of the tank or leave it at the top i know that it would prevent siphon off flooding but will this be able to pull all the detritus from the bottom if left at the top please help ps. not decided which fishes to keep as of yet arowana in mind at the moment but not fully decided is there any links that i can go to to see some sump set ups i have looked on u tube but mostly for marine set ups thank you for being there when i needed you're help