Interesting read.
I ran a similar experiment this summer with lanthanum chloride, which yielded no results. I used a BRS dosing pump to put a drop or two down my overflow pipe. I was hoping to see the LaCl3 bind with PO4 and then be removed by the Roller Mat felt, which it fed directly into. I was a little paranoid about dosing the LaCl3 so I diluted it down to 15% and only dosed a drop or two every 60 seconds, for about an hour then I would wait for an hour and start again. I would only dose during the day, when I could observe the tank. I did this for a couple of days and saw no decrease in phosphate, as measured with the Red Sea test kit. There was a strong LaCl3 odor in the Roller Mat so I am assuming that it was picking up at least some of the precipitate, but was it LaPO4 precipitate or lanthanum bound with something else, possibly carbonate?
I ran a side test, taking about 150ml of aquarium water, in a glass jar. I put 0.5 ml LaCl3 in and shook it up. The jar clouded. I let that settle out for a day, which it did. I drew two test samples out of the jar, while trying avoid disturbing it as much as possible. The first sample was from the top (clear) part of the jar; the second from the very bottom, where the cloud had settled. Neither showed an increase or decrease in PO4 from the baseline aquarium sample, which was .08 ppm.
I later read an article that mentioned something about LaCl3 only being effective with much higher concentrations of PO4. I eventually stopped dosing after about a week with no change in results.
I have been thinking of getting a Hach total phosphate test kit (much more expensive and complicated) but it claims to be able to measure organic and inorganic phosphate. Has anyone had any experience with this test kit or similar?
Aaron
