Just to clarify a few things
1) When people talk about "bio-pellets" please name the brand because NOT ALL these solid polymer pellet products are the same.
2) NO3 is produced constantly in an aquarium, every minute of every day. So the bacteria that consume PO4 are working 24/7.
3) PO4 in general, is ADDED to an aquarium via top-off water, food and as an impurity.
4) "Bio-Pellets" don't REMOVE PO4. PO4 is removed when your skimmer removes bacterial bio-mass from the water column that is produced by the solid polymer pellets.
5) In rare instances, if NO3 or PO4 hits near ZERO the bacterial action can slow down until more NO3 or PO4 is available. SO this is why we discourage use of GFO, otherwise NO3 may not be reduced. But if PO4 is still high after NO3 hits zero, just run a little bit of GFO temporarily.
If you're having problems with PO4 accumulating while NO3 drops, you need to look at your export system closely.
GFO removes PO4 by bonding with it and then you remove the GFO and dispose of it. When you harvest macroalgae you're removing PO4 from your system. The bacteria that consume solid polymer form little clumps of bio-mass that are sheared off of the surface of the solid polymer pellet. This bio-mass enters the water stream and immediately picks up additional bacteria in the water stream, possibly some proteins and carbonate particles and is a) skimmed out or b) settled out.
If your bio-mass settles out instead of being skimmed the PO4 is NOT removed from the water stream and will be a localized source of organics where it settles out. Settled out organics can lead to Cyano outbreaks.
So the KEY TO SOLID POLYMER use is to focus on EXPORT
I kept this in mind while formulating ecoBAK and while writing the Patent application. The solid polymer should have specific properties that facilitate the export.
So, bottom line...
1) Don't excessively agitate/tumble your solid polymer pellets.
2) Maintain high flow rates IN THE SYSTEM (not the bio-reactor) to prevent organics from "settling out" in your system
3) Use a properly sized/rated/high quality protein skimmer.
4) Consider plumbing your reactor output into your skimmer intake or at least into the skimmer compartment.
5) When starting out, use a partial dose of solid polymer pellets and add more every 1-2 weeks.
In summation, the bacteria is working. If your PO4 doesn't make it into your collection cup you have work to do. Speaking of ecoBAK (I can't speak for the others) I can say it really is that easy. And no you don't have to be a chemist to use it in an aquarium. As long as people understand the basic principles behind its function it's an "auto-pilot" method of aquarium filtration suitable for ALL marine fish and reef aquariums.