OK, So I now know how important they are...
Here is my problem.
I dont have a tank that is drilled, and I dont have any room on the back for an overflow. I could remove the HOB Media filter I just added to free up 6", but only if the overflow is needed.
I was looking at this one BIY
REFUGIUM FILTER KIT FOR REEF AQUARIUM 10 GALLON KIT - eBay (item 360045299939 end time May-21-08 18:22:08 PDT)
And thinking of DIY
Creation of the fuge pic thread
Both mention a Overflow or drilled tank.
What are my options here ?
\Confused.