Personally I would use a soluable carbon source like vinegar or vodka or mox of both instead of pellets.
With pellets there really is no control , you run the risk of the pellets failing if the reactor fails and not to mention they take up space , smell and are expensive.
If space is available I would combine a few different export methods .
Macro algae , GAC /gfo , carbon dosing , skimming etc.
my zoanthid systems are vinegar dosed and that keeps nitrates undetectable and po4 is also undetectable on a Hanna phosphorous.
With po4 so low the beauty is I can cut my carbon doses down if I need to or raise as I need to.
Between vodka , pellets and vinegar I've noticed that the zoanthids respond very well to the acetic acid and growth and colors couldn't be better.
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