Nitrates are now reading .5 and phosphates are .04 but phosphate was up to .16 at one point. I use BRS large particle carbon and rinse thoroughly. It's definitely not just at the tips and even the ones close to the tips have flesh at the end of the tips. I have been dosing the spectracide stump remover but have been having a hard time keeping the nitrates above zero. It would get used up quickly and I wasn't sure if the swings from zero to .5 or 1 back to zero could cause issues