Where to get Dupla products mail order?

I can't seem to find any Dupla fertilizers locally, could someone mail
me a good mail order source?

I also seem to have forgotten the proper names for the tablets
and the drops. Would someone refresh my memory?

I have been using Mike Trzonkowski's tablets, but they contain
nitrates and phosphates and I'm having a lot of trouble keeping
them under control. (tank is at phosphate ~1ppm, nitrate 10-15 ppm)

Jon Wilson
jwilson at b856s3_ssc.af.mil