Randy Holmes-Farley
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My Tank Thread
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So this would be safe to assume that my 10% water changes weekly aren't enough to not have to dose trace elements? I would need to dose trace elements as well as do water changes. As stated above, I dose Alk, Mag, Cal, Nitrate and Phosphate right now anyways to keep up with consumption. I was just always under the impression that everyone drove home about weekly water changes to maintain a healthy living reef tank.
Trace elements are a very complicated issue.
1. One cannot look at raw concentrations and know if it is enough or not enough or too much, because the chemical form has a big effect on bioavailability (and toxicity) of many trace elements.
2. We have no idea, even for a single chemical form (say, Fe+++ ion not bound to organics), how much is optimal for every organism. Natural levels may not be optimal (lots of scientific literature that many photosynthetic organisms in the ocean are iron limited).
Thus, a lot of it is trail and error, dose and observation.
That said, it is clear that water changes on the order of 10% per week or less cannot maintain rapidly depleting ions such as iron in many reef tanks, and that at least some tanks benefit from dosing it (and likely others, such as manganese). I changed 1% daily and still thought it was beneficial to diose iron and silicate, and other ions may have been useful as well (but I didn't test them).