Anyone has any idea that biohome or bioring can last ? Should it be changed after some time ? If so , how to tell it is time to change ?

Reason was , I dropped by bioblast on sat to top up my CO2, and asked Tan on his DIY carnister filter. He mentioned he used only sponge for the 6.5 tank, and said that the bioring may need to change after sometime as it emits too much NO3. I totally confused here , either he does not understand or two different schools of thought. The sponge, the bioring/biohome do not have any chemical effect, except they will house the beneficial bacteria to breakdown the ammonia->nitrite->nitrate. It is good thing right ? if the carnister produce a lot of NO3, it is doing its jobs. What is causing too much ammonia in the first place is the other matter. The more and faster breakdown of ammonia into NO3 , the better the filter media condition of the carnister , am I correct ?

He also mentioned best to keep in low NO3, that means, and low dosage of NO3. He demostrated with a multi-test paper strip, and true enough the NO3 is almost near 0 . Totally confused !!! Look at his tank water condition, the plants growth is crystal clear and bubbling like mad . Further more he is using 2 x 150w MH with he tank facing the main road with bright sunny sun outside. Hardly any algae . Of course, he is using a chiller . He is doing water change every 2 days of 20%, dose every day few drops of fertiliser and that's it !!

Also asked about his CO2 injection. He is using the bioblast internal reactor. Look like a honeycomb inside where CO2 is injected from the top, with a small area on top for mixing. How's this compare with the external reactor like the NA version , anyone has the experience on these two for comparison ?

Anyone has any comment on this ??