I'm sort of in the same boat.. I know this block picks up chunks of matter and doesn't do a terribly good job of filtering anything but the 'bigger chunks' that slip through..
But it does seem like a great place for nitrates to be created, only to be either pulled into the skimmer <rolls dice> or pumped back into the tank...
Any other oppinions? (I've taken it out and washed it clean in sw a few times, but it gets fairly nasty fairly quickly..and I'm also the guy that just cleaned out a horde of natural sponge things from his skimmer a week or so ago, so I'd love to drop a more effective barrier in there for those lil bastages)
EDIT - then I take about 15 minutes to read up on some of the professional oppionions on these wonderous 'polishing blocks'.
Basically, a trap for chunks o stuff.
Best cleaned out a few times a week lest they become a nutrient trap.
For the uninformed (since the blasted things arn't even mentioned in the manual...oh wait.. mine came with no manual!), they tend to sit never cleaned until a problem occurs.
That said, I do know no coneventional mechanical filtration is without tradeoff - they either need to be cleaned frequently or will be a source of nutrients to the system (and thus, end result, either produce nitrate or other more harmful substances).
Still seems the best method is creating a multistaged mostly natural 'ocean-like' system - with a healthy good bit of rock, fairly good sand bed, refugium for nutrient export and good critter import and a decent bit of 'props' (SKIMMER, powerheads, UV (the committee is still out there tho - just don't let yur fuge empty into it's water path and it makes alot of sense), regular (consistent!) water changes and some carbon changed out regularly.
Of course, that's assuming a sump or a myriad of devices attached all over the place... canister filters probably work along the same theory, but arn't what I read up about..
Oh, and I'm far from an expert, I just google/search 'well'.
My polishing block is already removed, water cleared and the bucket of changeout water seems un-needed (so say the tests).
If anyone goes the same route, do keep in mind those 'chunks o stuff' that very porous block might have caught might end up clogging a pump somewheres.. (I never liked prefilters, took up too much room anyhow)
But when yur hands stay as pruned as mine, that's not really a problem I guess.
(oh, and another last thought
If you used that big block of foam as a landing pad for sloshing water (like out of my skimmer), try a quick and easy bubble tower approach - pvc with slots or holes drilled in it will filter foam stuck in the end for the water to slosh through. Ends microbubbles fast and that foam is dirt cheap and easy to grab from time to time.)