A minute ago I was looking at the fishies in my 40 gallon and noticed that my aquaclear 300 had been unplugged sometime.....not sure when....might have been today or long before that....don't remember when I last made a point of inspecting it.....usually look at it daily...but might not have yesterday.
The sponge is nearly dry....my Penguin 330 luckily has been merrily working, so my parameters are okay-dokay. (Ammonia 0, Nitrite 0, Nitrate 10).
So, the question is, do I just plug it back in? Is there potentially something bad festering in there now? Or, do I replace the sponge? My tank is well cycled--so the lost in biologics is not devastating....
Having two smaller filters on the tank is some of the best advice I have gotten from the forum....many thanx!!!

I think I would give the filter a cleaning - the kind you do on a general maintainence schedule - nothing specially hard or invasive. Squeeze the sponge out really well and rinse it really well. (Since you have another filter and sponges are cheap, you could easily replace the sponge if you wanted to - then you would have no worries.)I do not think there is anything to be overly concerned about, though. Any stagnant water in the filter will be washed away in your cleaning, the sponge is either replaced or rinsed well, and the filter repopulates with the beneficial bacteria and all is well.

I LOOOOVE having two filters on each tank, if possible. It also allows be to se up an emergency tank on the fly with a cycled filter!