Bit a of a let down, no discernible change. Still appears to be 0.25. Maybe slightly less dark. I will wait till test 1 final time tomorrow morning before I can consider it a failure.
Of the three chemicals tested, I agree that iron citrate seems to be the best, but I would stick with GFO as much as possible. I agree that GFO gets too expensive in some situations, though. Lanthanum chloride should be fine. I don't know whether iron citrate or lanthanum chloride is safer. I guess the costs are close?
If you dont like my approach using cheap kalk (CaOH not CaCO3), then ,a cheap alternative would be to use iron nails instead of GFO.The nails will rust and the iron oxide will bond phosphates.There was an asian guy here that used nails with success.Randy Holmes Farley doesnt believe in the power of the nails here http://www.reefcentral.com/forums/showthread.php?t=1469717 but that asian guy allready prooved you dont need too manny and that they work well.Just avoid zinc coated nails .The thread of the asian guy should be somewhere on reefcentral but i cant find it right now.
I have actually never used Lanthanum Chloride. The costs should be similar between the two. Personally I would choose iron citrate over lanthanum chloride just out of concern for the possibility that precipitated residue of the LC (or iron phosphate) will possibly remain in the tank. If at some future point, through bacterial activity, the lanthanum or iron phosphate residue were to become disassociated, I would just feel more comfortable if the element that gets added back into the water column is iron rather than lanthanum. The risks to using each of them appear to be about similar.
I agree that GFO should be the first choice for most people. As for the situations where GFO is too expensive. That has me a bit confused. I am really not sure why GFO gets depleted so fast as compared to Iron Citrate / Lanthanum Chloride? I was always under the impression that GFO had a high surface area, but I am starting to question if a big portion of the GFO is unavailable for precipitation to occur as it is inaccessible (E.g not part of the surface of the GFO).
As for the costs of GFO, it is used in wastewater treatment, so I would expect it is not very expensive, and only is marketed at a high price within the aquarium trade.
Dennis
The asian guy sayd he didnt changed the water to his reef tank in 13 years.People says that nails will have a smaller surface area than GFO but i dont agree with this.As the nails rust, the iron oxide expands so there will be just the same surface area as the GFO has.As for the contaminants,i doubt that GFO is made from pure iron as well.Gfo might also contain traces of various otther oxides.I wouldnt use nails in my aquarium but is interesting idea.If i vere a GFO fan i could have used a cast iron plate in the sump and from time to time i would clean the rust and throw it as its gets filled with phosphates.Would be a much better and safer idea of PO4 export than ,,liquid GFO,, or LaCl. http://www.reefcentral.com/forums/showthread.php?t=1311723
I am not sure which would be safer to leave in the tank, the iron plus phosphate or the lanthanum phosphate. I think the major danger is the precipitate itself, which is equally problematic. If disassociated, the lanthanum and the iron both would react and be removed from the water column fairly quickly, I think. Iron tends to get bound or reduced quickly, and lanthanum will combine with other phosphate or with carbonate.Personally I would choose iron citrate over lanthanum chloride just out of concern for the possibility that precipitated residue of the LC (or iron phosphate) will possibly remain in the tank.