I received my test results and need help on which path I should take. My tank is a 40 gallon reefer, 5 fish and 6 corals. I've been having an diatoms issue for 4+months(I think it's diatoms) but may be something else. I had a prior post on Diatoms which gives the history but basically it all started when I added a man made rock in November which I think is made from portland cement and crushed stone??. I got it from a local college bio class mate of my daughter, they are not sure what it is made of which could be my issue of it leaching something not good for the tank. The red flags from the test mostly were Bromine 88mg/l verses Ideal 68mg/l and Strontium 9.84 mg/l verses 8.11 Ideal which were flagged as Attention Increased value. Fluorine 0.61 mg/l verses Ideal Value 1.32 mg/l and Iodine 24.35 ug/l verses Ideal Value of 65.92 ug/l were listed as Critical Too Little, Zinc was Critical Too High12.60 ug/l verses Ideal Value of 2.03 . The Zinc seemed alarmingly high. The test for my RODI came up completely clean , no issues. The Base and Major elements were fine, Salt, KH, MG, Calc, PO4, NO3, all in line. So the question is it my man made rock causing this issue, let me know what you think