Barry,

  Silicon seal leaves no lasting taste/odor, though some smells like 
vinegar initially.  That may secure your pump parts together.
  As per another list member's suggestion, I went to Walmart and bought a 
submergable Rule 12 volt 360 gallon per hour pump.  The bottom cage 
unsnaps for installation.  I cleaned the water tank by spraying 
inside with fuming muratic acid from a plastic hand pump sprayer while 
holding my breath, then let it react for 15 minutes.  Then a 10 minute 
water hose flush left it functionally as clean as new.  Next I ran a 
canister vac on blower mode and dried it in about 10 minutes.  Now, I 
used "Blue Goo," a popular silicone sealant/aheasive sold in auto parts 
stores which comes in a tooth paste sized tube.  I used this to secure 
the removable base to the tank bottom and form an outside additional seal 
around the pump's wiring entrance.  The base has slots around it, and I 
filled the top third with more of this sealant for that good to the last 
quarter inch pick-up.  After that cured, I just snapped the two ears of 
the base into the pump and did the wiring, observing polarity to keep the 
impeller spin correct for the pump design.  A backward spinning 
centrifugal pump will still pump but at greatly reduced capacity.
  So nice!  This puppy will get a variable resistor to control its speed 
sometime.  Very satisfactory piece.  The price was about $10.
    John