Potassium Metabisulfite and Citric Acid Cleaning solution:

Caution: Be careful of fumes  Tom wanted some ratio for citric and meta with a little science behind it.  This is what he came up with involving the pH of the water. 

 Whatever you do, dissolve the citric acid in warm water first and add the meta to it. Be careful where your nose and eyes are. Sudden fumes are over-powering.

For soaking the frames for our lees filter, he uses .25 pounds of citric acid dissolved in 1 gallon of warm water with .016 pounds of meta.  For filters and such use the manufactures recommended ratio.  The above pdf ratio is for general disinfection of equipment and tanks. 

Different ratios abound for different application. It is a very powerful cleaning combination.

Sulfur Strips need a hole in them to insert a piece of wire (picture hanging wire, etc) long enough to reach the center of the barrel. Used for dry storing a barrel. Should re-burn monthly if storing a dry barrel.  I do not know a lot about sulfur strips, but we carry them.