I believe it is snake oil and personally don’t believe in adding chemicals to the tank. I can’t count how many times I have read on numerous forums how someone became impatient and added one of these wonder cures to their tank and soon after experienced disastrous results.

Ferrous Oxide has proven to be very safe method for binding inorganic Phosphate PO4. I prefer Phosban brand because it has the least amount of residue.