for anyone it may interest...
I e-mail NextReef and here's the answer (thanks Dave!):
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It can certainly be done. You will need to move about 250 gph of water through that setup to fully fluidize them, and may want to use the sponges to contain those pellets. They will clump a bit at first.
If you have trouble getting enough flow through the reactor, try replacing the two 1/2" ID fittings in the lid with ones to accommodate a larger diameter hose. We use a 5/8" inch fitting with our BioPellet-specific reactor - it's a big improvement over the 1/2" ones. The lid is tapped 3/8" NPT.
We've had great success with a Mag3 and the larger fittings, and any pump in the 250-300gph range should be fine.
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