bulkhead/plumbing question/idea

[pbauec]

I picked up a 90g and removed a huge unsightly overflow that took up way too much real estate. I am plumbing it soon and want to repurpose the previous drain in the bottom of the tank as the return.
The hole is 2.5" so it was a 1.5" bulkhead, my pump has 1" output. Would it be better to up the output to 1.5" to match the bulk head or to pipe in 1.5" to the water line with flex running thru it? (1.5" then acting as emergency overflow)

 

[AZDesertRat]

Most pump manufacturers recommend stepping up one size on the plumbing to lessen the headloss due to friction. Make sure you run the return all the way up to the surface so you don't have problems with backflow when the power goes off.

You may also find some good tips and useful information here:
https://www.reef2reef.com/threads/installing-bulkhead-tips.34973/

 

[pbauec]

I had hoped to use loc line at the top of the return, so i would be stepping it up for the run then down again at the top ?

 

[AZDesertRat]

At a minimum I would install a 90 degree elbow on the top, bush it down to 3/4" and use a LocLine wye and two 3/4" LocLines with either straight or fan nozzles. Better yet would be to place a tee on top then bush each side down and use two LocLines and eliminate the 3/4" wye restriction. Depending on the pump the restriction could add quite a bit of headloss and reduce the pumping rate significantly.

Then again if you have a pump with a 1" discharge outlet you may have more pump than you need for a 90G reef. Most pumps in the 500-900 GPH range have a 3/4" outlet. Most will recommend around 5x your display volume or 450-500 GPH after headloss in a 90G. It also depends on the size of your sump as you do not want too high of a velocity through the sump or you will have microbubble issues and an inefficient protein skimmer. The larger the sump and the better the baffle placement the higher you can flow.