So here's what happened...
The power was accidentally off on my 37gallon tank for I'm not sure how long, it could have been over 24 hours, so we can safely say all the bacteria in my two Aquaclear 50's were dead and gone.
So, I "borrowed" the biofoam from a filter running on my 15gallon and stuck it in one of Aquaclear 50s so I'd have some bacteria to start with. (the 15gallon is well established and has been running for years, and that power outage did not affect the 15g).
How long should it take for both my Aquaclears to get re-established? (the 37g is stocked with about 8 1" africans, a cuckoo cat, and a pair of siamese algae eaters.