Need help with sump size setup

[tran]

hi everyone.

I am preparing to build a DYI sump for my new 75g. Will be setting this up soon.
Not sure which is a prefer sump size. a 20g long or a 29g tank, 20g tall. (most local petstore carry these size tanks)

I've heard many members in here saying that 29g tank under the 75g stand is very hard to move stuffs around . 20g long tank is little little short and 20g tall is not enough room. Has anyone have experiences on this?
Could you members help on this.

 

[Turbosnail]

I have a 20 long under my 90. I have it split up into 3 sections.

 

[Killarsox]

The bigger the better. I use a 30g under my 90. 36"x12.5"x16.5"