I've very familiar with AD -- its a simazine (6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine ) based pesticide (there used to be many of these in the late 80's - early 90's, I think AD is the last one still for sale )
It's pretty much aquatic Agent Orange if mis-used (either overdosed or used too frequently -- it takes about a month for the dosed toxin to break down in the aquarium).
Studies in India on local fauna (ie tropical fish) showed problems with health and growth at 1.0 mg/l -- and the recomended dosage to kill algae is from .5 - 1.0 mg/l -- so the recommended dosage is potentially toxic, especially since most hobbyists (ie folks who don't have a few dozen tanks) are not :
a) going to know their tank volume to the liter
b) going to use a proper graduated dosing device (ie pipete or large syringe)
meaning most people guess at putting in "x number of capfuls" -- and can easily overdose their system.
(unfortunately the EPA tests were on catfish, sunfish, etc -- have you seen some of the chemical cesspools catfish and sunfish will breed in ?
but I digress)
There's a good article on simizine based treatments here:
http://www.thekrib.com/Plants/Algae/simazine.html
I'm not trying to attack you, and I'm glad your fish are doing ok.
I'm just hoping to help the next dozen people who google search "algae bloom", find this forum, and read this thread.
I was 15 once too = and I made plenty of mistakes along the way. If I wasn't willing to make those mistakes, and more importantly, listen to the folks who had advice other than "buy this chemical it works miracles", I wouldn't have a fishroom full of happy fish today.
In general - if you can find something at a big chain store but not at small quality stores like Ned's, there's a reason for it. If it was a good idea, Ned would sell it.
Kinda like not finding Big Mac's at a health food store