I haven't dealt with them but I did find the following a few weeks ago:
http://www.gardenlink.com/AquaticSpikes.htm

-- Mark

"JLu3140998" wrote in message
...
hi group

ive heard of fertilizer tabs that you only need to use once a season-
can anyone suggest vendor that sells in large quanity.
i need 4-500 or more
thanks

john