Take it all apart. Put the fish into a separate container in all new water. (plastic storage container with lid will work. Rinse the filter and media, then set it up to run on this bin.
Remove the substrate and the Jobes stakes. Rinse the substrate really well. Throw away the jobes stakes. Wipe down the sides of the tank. Clean everything else.
Reassemble it all except the fish and test the water. Is it clear enough? It may be a bit cloudy, but the white stuff on top is gone? Tests OK?
Put the fish back in.
Skim the water surface with any of several things that might pick up the white stuff. Try a good quality paper towel, a fine fish net, filter floss or other things.
Do a couple of 100% water changes, including VERY thorough gravel vacs and remove the Jobes spikes. Clean the filter media and add all the different filter media and water treatments that get rid of toxins:
Chelator such as EDTA (Bottle will say 'locks up heavy metals' or something similar)
and things like Cuprisorb, Nitrasorb and any similar products.