JBL Iron test kit

[dodgy67]

I have been dosing Iron from a 300mg Ferrous Gluconate tablet containing 35mg Ferrous Iron at 3ml twice a week into 100 gallons as a recommended dose. I dosed 3ml yesterday today I received a JBL test kit, tested and it showed <0.02, white on the scale.

scale goes from 0.02 as white up tp 1.5 deep purple.

I have a lot of Halimeda macro algae to control nutrients so assuming this is taking up the iron, to retest I dosed another 3ml and reading still showed <0.02, to prove if the 5ml test bottle solution was working i dipped a cocktail stick into the iron solution and dipped it into the 5ml bottle the colour changed immediately to 0.2 which is the high side of OK, 0.05 0.1 0.2 by my reckoning I would have to dump the whole 100ml of iron solution into 100 gallons to show up on he scale, are these test kits so inaccurate, anybody else having the same problems

 

[laga77]

There are no accurate hobby level iron test kits.

 

[bertoni]

The typical ocean levels of iron are extremely low:

http://www.reefkeeping.com/issues/2004-05/rhf/index.htm

I don't know how long even chelated iron would stay in the water at higher levels. It tends to be consumed or bound rather rapidly, from what I can tell.

 

[dodgy67]

I was hoping to show from the test kit that dosing 3ml twice a week was maintaining the iron uptake of the tank (greedy Halimeda and corals) but whats the point if I have to dose to excess to show up on the test kit as normal (100ml0

 

[dodgy67]

As an experiment to test out the test kit I have dosed 9ml of iron solution in a pint of RODI dripped over a 2 hour period and retested and is still showing <0.02mg/l which is still effectively showing unetectable

 

[bertoni]

Are you sure that the kit is detecting chelated iron? I might increase the amount in the RO/DI a few time to see what happens.

 

[dodgy67]

Jonathon, just re-dosed at 20ml iron solution in a pint of RODI dripped over two hours re-tested liquid in 5ml test bottle still shows clear, so still <0.02mg/l on the scale which is showing is less than ok

 

[Dan_P]

I am interested in your iron study. Here are some ideas that might be useful to you.

Chelated iron may reacted very slowly with your test kit. I had to wait seven hours to reach a steady value using Seachem. Their tech support was not surprised by this.

As suggested, add chelated iron to a pint of RO water until you see a positive test result. Of course, this is not a clean experiment because the test kit or the chelate iron or both are out of whack. Try it anyway and see if test result and calculated amount in the RO water are close.

You should Google the "oxidation rate of chelated iron (II) in seawater". It might be fast, being converted to the less useful iron (III) in the form hydroxides and oxides.

If the iron dosing to RO water gives encouraging results, repeat it with tank water to determine how fast it disappears. You might find it disappears faster than the rate of reaction with the test kit reagent.

 

[bertoni]

Thanks for the information on the SeaChem test! I suspect that the chelation is the issue.

 

[dodgy67]

Dan are you saying add 5 drops of reagent to a pint of RODI then add iron until I see a change

 

[dodgy67]

Dan have just after several hours seen a slight change in the colour has now moved to 0.05 low end of ok will leave overnight so appears the test kit would not react to a weekly or bi weekly dosing of 3ml in 100g

 

[dodgy67]

Have left the 5ml bottle overnight and it seems to have cleared, wiil have to repeat the test over the next few days to check on depletion level, but unless the test solution is raised up to a distinguishable colour this may be difficult