Product review (2 stars): Strange stuff
Ensure that you are salting your pond when you use this as it asphyxiates the koi.  I have lost 4 of them using this product and algaefix.  Remember that anytime you kill or remove vegetation from the pond (algae is vegetation) it raises the ammonia levels in the water and makes the koi lethargic, loss of appetite, and eventually kills them after they do the "funky chicken/unresponsive" swim.

Salt will combat this and save your koi if you catch it soon enough.  Make sure you use rock salt and use 1 cup per 100 gallons of pond water.  This is what saved my 2 largest koi.

Does this product clear the water as advertised?  Yes.  It clears EVERYTHING.