I don't think your original though has failed. I think you are trying to do too much.
Here is a snippet from MARINECRITTERS thread which I posted a link to above:
"...the flow of new and old water exiting and entering the sump is very slow, infact I dumped a 16oz bottle of live phyto in it last night, and I came down this morning to see the sump water is still slightly green.....
If I dumped a few bottles of LIVE phytoplankton in the sump, some of the phyto would feed the sponges, filter feeders, zoo plankton,etc and the amount that stays in the sump can consume nutrients from my tank, it would essentially be a free floating refugium......
"....phytoplankton is really a plant.....consume nutrients in the form of phosphorus and nitrogenous waste.....so in my mind this type of filter that I call the phyto filter would be perfect for a nps tank
What you are attempting to do, is essentially do the same idea, but in a seperate additional fuge rather than the standard fuge. You are also thinking of attmpting to culture rotifers with the same system. I think you should walk before you run. IF you want to culture your own phyto with an in-line system - get that setup and running before adding another variable of rotifers to the system. See what kind of growth you get, and if it even works. Maybe you won't get as much growth as you think, and you can't support rotifers....maybe it works too well and the flow-rate you need to keep through the phyto fuge is too high and you flush out rotifers at too fast of a rate.
Get one piece of equipment working and stable before adding another. It will be far easier to see where the mistakes are and to debug.
