put some bulkheads thru the back of the tank with covers on them
I agree.
Although I have used them, I'm not a fan of stand pipes.
I prefer to drill on either the back or on a side near the tank rim, eliminating those long vertical pipe cluttering up the inside of the tank.
I also prefer to skim the surface for water to the sump, as the air water interface seems to collect the worst most toxic gunk, and hindrances to air exchange stuff (even though it is not the most visible).
And because I keep riverine species I prefer the water to enter at the opposite end to create flow pumping along the length of the tank to the sump.
I am also using a 125 gal as a sump, but as opposed to the standard way of using it (beneath the tank) I have it placed kitty corner, and only use about 1/8 of it for bio- and mechanical media, the other 7/8th is heavily planted with aquatic, semi-aquatic and terrestrial plants, which also hold plenty of beneficial bacteria but also help to mitigate nitrate, something most sumps don't do.
As you can see, from a shot while completion was in progress, the space for the pump, mech and bio media is tiny in comparison to the rest of the sump, that was eventually heavily planted.
With this configuration, there have never been ammonia speaks, or even nitrate concentrations of more than 5ppm.
I believe the heavy plantings eat the nitrate as fast as it is produced by metabolism
