Planted Tank VIP
Join Date: Jul 2002
Location: Victoria,British Columbia, Canada
Ok.. A word of warning from one Aquaclear nut to another....
I use the exact same method to prevent surface disturbance. There is one.. Minor, yet rather significant point you must be aware of.
If your bottom sponge gets clogged with a sponge in the top like this, you may find your filter leaking water around the top. If the water flow gets too restricted through the bottom sponge they lift, and the water gushes UP around them. This splashing will start dripping down the back of the filter.
I'm only saying this because not one, but two of my filters did this last week.
That being said.. this is a great way of preventing too much surface disruption.