Have not tried it, but...
I believe those products are designed to provide an area of low oxygen flow for bacteria to exist that reduce nitrates. The bacteria would need to seed it before it had any effect. I'm not sure that a week and a half is enough time for that to take place.
Denitrators work in a similar fashion requiring a very low flow rate through the unit. Those units require a separate feed via a pump or a branch off system. I can't tell you if they work either.
Please let us know if it works out for you.