DSB in sump?

[drkphx]

I have a 75 gal. with a 30 gal. sump. I don't want to have more than a 3" sand bed in the 75. Would there be any benefit of having a 6" DSB in the sump?

 

[fshhub]

yep, definitely much more benefit than not, but most will say that anything over 6 inches is a waist of money, no extra benefit
another thing you could do is make it a refugium, you already hav the dsb, just add algae, and you'll have food for algae eaters, as wella s improved filration and nitrate reduction, also some pods or some lr(which will have pods) one piece, will have extra benefits in a refugium