My BC29 has been setup for 4 weeks. Ammonia is 0 / Nitrite is 0 / Nitrate was 15 four days ago and 10 today. Seem to be seeing Coraline algae growth now and Diatom bloom is starting to dissipate. I've just removed the bioballs and put the mediabasket in today with just the filter floss in for now. What's the general opinion - can I go ahead and add the Purigen and Chemi-Pure now also or should I wait until Nitrate zero out?

Thanks.

No, now would be the perfect time to add the chemical media. It will help with the nitrates along with water changes.