[cheeks69]

Also AFA heavy metals are concerned I'm not worried.

RICHARD HARKER:

we showed that an ICP scan analysis of natural coral reef waters found that heavy metal concentrations in the collected water were considerably higher than published seawater data. (Harker 2004) More significantly, the analysis found levels of heavy metals in coral reef water to be very similar to the levels of metals in my own reef tanks and only slightly lower than those reported earlier for reef tanks. Perhaps natural coral reef seawater has elevated metal levels compared to the open ocean. Perhaps the complex nature of seawater prevents an ICP scan from providing an accurate view of metal content of seawater. In either case, we have insufficient evidence to conclude that reef tanks have elevated heavy metal levels. We therefore have to reject the first element of the author's proposed hypothesis, that the average reef tank has concentrations of heavy metals much higher than those found in natural seawater....
....As a rule the toxic ionic proportion of a metal in seawater is generally low. Most heavy metals in seawater are organically or inorganically bound, and are therefore non-toxic. Depending on the study, ionic metals can range from 20-30% of total dissolved metals. That means that 70-80% of the concentration of heavy metals in seawater is not in a form that is toxic to reef tank inhabitants. That does not mean the metals are rendered permanently non-toxic, only that at the time of analysis, they were non-toxic. Any hobbyist who has dosed a tank with copper in an effort to rid fish of parasites has experienced this effect first hand. It is very difficult to maintain a constant level of ionic copper in a tank, particularly if the tank has sand or live rock. While the level of total copper remains unchanged, testing for copper will show that levels are declining. Hobbyist copper tests measure ionic copper. As copper complexes with organic compounds and is sorbed onto calcium carbonate, the proportion of ionic copper declines as does the toxicity of the copper. That is the case with all metals that enter a reef tank.

http://www.advancedaquarist.com/issu...4/feature3.htm