I use it all the time.
I read that some people actually pour H-peroxide directly inot tank for algae. Is this true?? Would it work as good as Excel??
I always thought that you should just use it as a dip.
I use it often. Both, directly into the aquarium and as a plant dip. I am hesitant to use a syringe and place it directly on the algae in a tank containing inhabitants--I am afraid that they swim though a concentrated area and burn their gills, perhaps this is too cautious.
When directly injecting into the tanks, I am comfortable with 1 ml p/gal p/day. If the algae does not begin to respond, I repeat the doses every 12 hrs instead of every 24 hrs. If this too fails, or is too slow, I go to 2 ml p/gal pay, etc. I have never had to use greater than 3 ml p/gal p/day for very long to control even the most stubborn case of algae. I would be careful with shrimp and other 'dainty' inhabitants--or, in other words, use caution! I have been using it for a couple of years now, at first I was VERY cautious--then I relaxed, a bit. Go slow until you gain a 'feel' for its' use and effects on the inhabitants of your aquariums--but then, that is good advise with nearly everything.
Now, all that said, I have seemed to notice that high doses of hydrogen peroxide, over time, seems to damage/kill vals, anacharis and other plants which I have forgotten about. The crypts, java moss, java ferns, swords, etc. all seem fine with the treatment, however, if you are going to use it for prolonged periods of time KEEP AN EYE ON THE PLANTS. Keep an eye on the fish also, if you happen to notice any signs of distress, halt treatment immediately--and, again, like with almost everything you place in your tanks.
Somewhere, I read that algae has no mechanism(s) to deal with abundant oxygen, and this is why it is so effective (I have found it to be much superior to Excel)--however, I am unable to find those sources now. Perhaps someone else knows why it is effective and will post the reason(s.)
Good luck!
Regards,
TA