Aliminum

[dan]

WOW!!!!!!! that was heavy man. :shades

[Instar]

Well basically you are all right. Some of the heavy metals, IE: copper, aluminum, lead, chromium, tin stay available as ionic forms. However, at normal pH in sea water (our tanks), with available carbonates, these will tend to be incorporated into precipitates, assimulated into tissue and made insoluable, unavailable complexes. They are layered in and under the coraline algaes on the rocks, taken up in macro algaes, adsorbed deep into the sand bed and turned into skeletal structure where they are no longer an issue and can not be removed from the tank simply by water changes. Carbonated skelital structure matrixes are extremely stable. Until, they get deep into the substrate and are then again made available due to the low pH and anaerobic bacterial decomposition. And, even in there, the greater majority of such precipitates is supposed to be very stable and permanent. If the pH was to go to 2.0 deep in the sand bed, that would be quite another story, but, it won't go that low. Therefore most metal precipiates are quite stable and insoluable. If a tank is maintained by regular water changes, any of these ions that do come into play if ever they do, are removed. There is an issue of build up in ionic, chelated and bioavailable forms of metals over the first couple years but, this can be at least partially overcome by doing a couple of water changes of a greater percentage and/or more frequently than the monthly 10% during the year. The biggest issue would be the return of copper as that one is the more easily dissolved precipitate at the lower pH of the deep sand bed. However copper is not as readily available as the others might be. In other words, if you are using RO/DI without additives and no meds in the tank, there shouldn't be any source for copper (no brass ball valves or housings/impellors). And then if there was, it can only exist for any length of time at about 8ppm at a pH of 8.0 and up. I believe that the various elevated levels of metals as Josh and Gary referrs to in Shimek's publication, accounts directly for the difference in larval survival rates between the different mixes.