Fwiw, Raritan K.O. doesn't stand for "knockout"...it stands for Kills Odors. It was the first of the product line my company, Peal Products, (named "Pe" for Peggie, "al" for my husband Allen) developed and put on the market in 1987 and was also the first tank product that wasn't one of the gawdawful Thetford portapottie chemicals. Its active ingredient is live aerobic bacteria. CP ("cleans potties") is its companion product. I sold my product line to Raritan in 1999.
Raritan only markets C.P. as a bowl cleaner, but it happens to be the best sump and sink drain cleaner on the planet.
Sumps: Fill the sump at least 1/3 full with clean water...add 2-3 oz of CP when it can remain at least overnight (the bacteria need time to work)
Sink drains: close the drain thru-hull, put 1-2 oz of CP down the drain and fill the drain with clean water...again when it can stand at least overnight. It can remain in sumps and drains for months without harming anything, it just exhausts its food supply (the stuff you're cleaning out of 'em) in about 24 hrs
--Peggie