The MPS / Nature2 Missing Registration Mystery

Searching in Purdue U's database of EPA registrations
http://ppis.ceris.purdue.edu/htbin/epachem.com
for:
Potassium monopersulfate
Oxone (Dupont trade name)
37222-66-5 CAS number
I came up with zip.

BUT, Nature2 claims to have a registered spa sanitation system, involving MPS
http://www.nature2.com/spaproducts/nature2spa.asp
"If used with MPS, the most recommended spa oxidant, Nature2 Spa becomes a complete spa sanitizing system - the only non-chlorine spa sanitizing option available. And managing your spa is easier than ever; Nature2 Spa slips into your spa filter and lasts up to four months."


http://apps.cdpr.ca.gov/cgi-bin/labe...l?prodno=54550

I did find a more complete set of approved labels, with other information. I'll have to explore this later:
http://apps.sd.gov/doa/prrs/search/P....asp?key_m=779

Found the MPS Spa "recipe":
https://apps.sd.gov/doa/PRRS/ImageVi...47156&Type=pdf

That's all for tonight.