Hey, I am currently planning out my 75 gallon build and was curious what size of refugium I should use? I am limited by the space underneathy my stand, but was wondering if a 20 long would be sufficient or if I should try and fit a bigger tank. I would like to do the DIY route rather than spend a bunch of money on an acrylic one. If anyone has any recommendations and or used tank they would like to sell me just let me know. Thanks.