I have not read this whole thread but I did read some of it. I've got to say that I would not be comfortable dosing Lanthanum on a regular let alone continual basis. I've used it before in moderation to lower phosphates by dosing via an IV bag directly into a 10 micron felt filter sock where the water enters my sump. The results of a very small amount of Lanthanum were almost scary in the amount of percipitate that it creates and how fast (minutes) that the filter socks would harden and clog up. The results were nothing short of shocking in that it really reduced my PO4 in a hurry. I was very cautious in my application and achieved the results I was after very quickly with very low doses and without repeat applications. Well actually, I did repeat the application one time a week or 2 later. Between the crushed coral/sand removal, LaCl application, rinsing my mysis and the addition of high quality GFO my PO4 dropped to 0 from .10 before I took action. This was after 7 years straight of complete disregard for PO4 levels.
In my mind, if you guys are using a reactor to continually dose small amounts, then you are doing the equivilent of putting lipstick on a pig. If you want to get phosphates under control, it's best to attack it at the source. As part of my Phosphate control, I eliminated all of my old crushed coral and sand, I began rinsing my mysis shrimp with RODI water which was a follow up to my very controlled application of LaCl which I repeated one time after the first application. LaCl is serious stuff. It's also critically important to remove the percipitate from the water immediately otherwise, the PO4 will just increase again as it was not really removed from the system.
I'm not faulting you guys on your endeavor and you may well be onto something but to me, it sounds as if you guys are playing with fire and delving into something that can be very risky for your tanks. I hope I am wrong and will certainly follow this thread as the reactor idea is intriguing but the IV bag/filter sock method is reasonably safe when done properly and with moderation. When I decided to try LaCl a couple years back, I did a lot of research (hours upon hours of reading) and I went with the safest proven method of application. A reactor was never even a consideration let alone an option from the circles that I conferred with and read up on. As I said, maybe you are onto something but to me it sounds very risky and I'm of the midset that the use of LaCl should be done with surgical precision. I measured my doses with a syringe and applied it to the water mixed in RODI at a rate of a couple drops a second.
Obviously, it looks as though the OP has done his homework. I can only suggest in the strongest terms that anybody considering the use of LaCl to do your homework. There is a very good thread here on RC on the subject that the OP referred to in his first post that was started by Gary Majchrzak and while it may be a long read, the use of LaCl warrants the time being taken to understand the application, the pitfalls and the safe use of the stuff. If you didn't see the OP's first post, here is the link to that thread.
http://www.reefcentral.com/forums/showthread.php?t=1474839&highlight=lanthanum
Here is a link to my application of LaCl. It was safe (by my standards), scientific in its application and the results were stellar.
http://www.reefcentral.com/forums/showthread.php?p=16841760&highlight=lanthanum#post16841760