I tested it on a fish tank with measurable phosphate at .8 ppm. The next day after dosing phosbuster there was no detectable phosphate. So either it precipitated out the detectable phosphate or it interfered with the test kit. I have used it to correct algae problems on reef tanks without any harm to any livestock so I don't think it is just causing a negative test. I only mention that because I have heard there are some ammonia "removing" products that don't actually neutralize ammonia but just give a false reading on ammonia test kits.

I do not know if the phosphate is permanently removed. I emailed carib sea a couple of times for more details but no response. I think it's worth a shot to quickly try and correct some phosphate related algae problems but it is rather expensive so a more permanent natural solution should be worked on at the same time.