Keep in mind though, even if you dont get a reading for phosphate, doesnt mean that you dont have any as the algae is probably absorbing it all and would cause a false reading. I know that is what happened to my smaller tank that had hair algae, I didnt have any phosphate readings at all but algar was growing everywhere. I got a seahare and it did a great job on it but unless you fix the cause, it will never go away, my issue was overfeeding.
