Help Testing Red Sea Trace Colors (Esp. Iron)

[Andrew Schubert]

I've been dosing Kalk to my reef tank, and have just started adding Red Sea trace colors to the mix as well. Since I can't really dose by Calcium uptake due to my method of dosing, I picked up the trace colors test kit to test the elements. I haven't had any issues with the Iodine or Potasium. HOWEVER, I've had nothing but issues with the Iron supplement.

After initial testing the Iron, it was at 0. So I began slowly dosing the Iron supplement to the tank over a week or so, testing each day. However, by day three and dosing about 250ml in total the test kit still read zero.

I figured I had either a bad iron supplement or bad test kit. So I picked up a new one of each. I dosed according to the instructions to raise my Iron from 0 to .1 (which is a whopping 360ml). On initial test the kit final showed evidence of Iron (.25). Now, just 2 days later I test it once again and its back to 0! I can't, and can't believe nyone else can afford dosing 350ml of this stuff daily? So what gives? Has anyone else had issues keeping Iron level in their tank? I'm wonder if something in the tank could be absorbing it?

 

[P-Dub]

@Randy Holmes-Farley . I'm certain Randy has some very helpful insight. You might want to post this in chemistry forum...

 

[Billldg]

If I remember right, trace color test kits are very inaccurate. Personally I added .5 ml of all 4, A,B,C, and D everyday. If you don't have a heavy load on your tank then water changes should take care of any issues.

 

[Andrew Schubert]

So I found this answer on FAQ...on Red Seas website.....basically it sounds like their iron test kit is useless then????


No, your test kit is not faulty.
The iron cycle is a very complex in the marine environment and it can be found in many chemicals forms, from free ions through inorganic and organic molecules up to large colloids connected to metals. This “soup” of chemicals increases the probability of spontaneous reactions, causing elements to spontaneously switch between phases.
These changes are enhanced and controlled by many factors such as salinity, pH but mostly by changes in alkalinity and the amount of organics and colloids in the water.

In a closed system such as an aquarium where there is often a high organic load and many dissolved organic colloids, the amount of free iron could be very small although the total iron could be very high. Usually this situation will lead to a darkening of the corals due to growth in the zooxanthellae population, and an outbreak of phytoplankton and other macro algae, even though you may measure zero levels of iron. On the other hand, in very pure saltwater most iron will be present as free-iron ions which can be toxic.
After a few minutes from the time you add the iron (Coral Colors C) to the aquarium you will probably measure levels around 0.05 ppm. This may last for several hours before it drops to zero (usually within 24 hrs). The reason for this is that the iron may have precipitated or bonded to organics substances.
The use of the Iron Test within Red Sea’s Coral Colors Test Kit will ensure that Iron is not over- dosed as long as the iron is still in free form. However the test will not detect iron which is not in its free form, and therefore a zero reading should be treated carefully as any overdose will cause stress to corals.