Neither, They just go into a BRS reactor or any one like the Phosban reactors. The whole premise is basically Solid Vodka dosing (Carbon Source) Limited to a reactor opposed to the whole system being dosed with liquid carbon (Vodka). They have a break in period for the Bacteria to start producing the strain that will consume No3/Po4 and ultimately be removed by your Skimmer.
Please note that all these Pellets require a highly efficient skimmer to be effective in removing these waste products from the water column and some have adverse side effects such as Diatom outbreaks on the sandbed and some cases of Cyano (Red Slime)
They do quickly go away in my case with the Warner Marine product (Eco-Bak) and It has been keeping my tank pristine with no other products being used (GFO/Phosguard)
All my test are at 0 using Salifert test kits. And my coral looks better than the tank i used to Vodka dose on and they were Amazing as far as Color and growth. This is JMHO and is been only in use a short time so far. It remains to be seen how it does long term, But so far i am very pleased.
Bill