Minor elements

[fishRus]

In my 100 gallon reef system calcium, alkalinity and magnesium are being used at a consistent rate can I assume ( yes I know want assume spells ) iodine, potassium, strontium and trace elements are also being used at a consistent rate or do I need to test each one separately

 

[Dennis Cartier]

The standard practice being that you should not dose anything you are not testing for. Trace elements being the exception as they are not easily tested except by ICP. Dosing trace elements at a manufacturer's suggested schedule, should be safe (depending on the Manufacturer of course).

I have a good example of this that I was just wrestling with.

I don't normally dose iodine, but added some ESV iodine twice in the last 2 weeks (at the suggested safe dose as recommended by ESV). With the first dosing, I noticed my alk started dropping the next day. I was unsure if the drop was related to the addition of iodine or perhaps my LaCl reactor was the cause. I dosed again on Saturday, the 18th, and starting yesterday I can see a drop in alk starting and accelerating today.

So my gut says, hey I must have been depleted on iodine and am getting an acceleration in growth after dosing, but my head says, not so fast. I also see some weird cyano like film that I get in high light areas on pumps, receding after the iodine addition. I also witnessed the same receding and rebound of the film with the first dose. On one hand, I can support the argument that I was iodine limited, and the other the receding of the bacterial film might suggest that iodine is elevated enough to contribute to it's receding (which would suggest very high iodine).

My solution is to go ahead an order a iodine test kit to find out for sure, and then if low, I will add a tiny daily addition to my dosing to prevent it getting too low, and then periodically monitor to prevent it accumulating (which it is known to do).

 

[Randy Holmes-Farley Verified Community Expert]

In my 100 gallon reef system calcium, alkalinity and magnesium are being used at a consistent rate can I assume ( yes I know want assume spells ) iodine, potassium, strontium and trace elements are also being used at a consistent rate or do I need to test each one separately

Depending on what you feed, most minor elements do not necessarily deplete at all. Potassium, for example. It did not deplete in my t

Strontium gets into calcium carbonate at a mostly fixed rate, whether by a coral or abiotic precipitation) , so it’s consumption is directly tied to calcification. I personally do not think dosing it is useful for mist reef tanks.

Iodine is rapidly consumed by algae and its demand is unrelated to calcification.

 

[Dennis Cartier]

Iodine is rapidly consumed by algae and its demand is unrelated to calcification.

That might be the clue for my increase in alk usage as well. I noticed my macro's got very happy after the iodine dose.

I just checked on 3 clumps of different Halimeda I recently added, and they are starting to grow. So that may be the link between the iodine addition and increased alk usage.

 

[Randy Holmes-Farley Verified Community Expert]

That might be the clue for my increase in alk usage as well. I noticed my macro's got very happy after the iodine dose.

I just checked on 3 clumps of different Halimeda I recently added, and they are starting to grow. So that may be the link between the iodine addition and increased alk usage.

That’s certainly plausible.

 

[djf91]

@Randy Holmes-Farley is this iodine consumption also true for corraline algaes?

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley is this iodine consumption also true for corraline algaes?

A number of organisms incorporate it, though that does not mean they necessarily “need” it. I’m not sure on corraline, but I expect it takes it up.

 

[Dennis Cartier]

Following up with my iodine dosing results. I observed the same pattern this week, a slowing of alk uptake starting from the 21st. I last dosed iodine on the 18th.

Today I measured my iodine level using the Hanna method developed by @Rick Mathew , @taricha and @Dan_P . Before dosing I got 11.62 ppb. After testing, I dosed 6 ml, the suggested amount of ESV Potassium Iodide ( 1 ml/20G ), and retested after 15 minutes. On the follow up test, I got 115.19 ppb. That is a bit higher than the recommended range (60 - 80 ppb), so I am not sure if I am over calculating my water volume, or the ESV recommendation is aggressive. They don't say how much 1 ml will raise iodine by, so I am not sure which is the case. By my calculations, it looks like 1 ml of the ESV Potassium Iodide raises my level by 17 ppb. The ESV bottle shows 1% potassium iodide, 0.5% sodium bicarbonate, 98.5% deionized water.

Tomorrow I will measure again and see what the 24 hour drop was. I am hoping I can establish a daily addition to stop it from depleting below 30 ppb.

 

[Dennis Cartier]

OK, I just finished testing iodine, approximately 24 hours after my last test (probably closer to 23 or 22 hours). The latest test came in at 32.51 ppb, which is a lot lower than I would have guessed it would be, before the test. In the time between dosing and testing yesterday, to today, the level dropped by 82.68 ppb.

Hmm, I am wondering if the speed of uptake is driven by an accumulated deficit? Meaning after establishing daily supplementation will the uptake slow as whatever is clamoring for it obtains it, and starts to uptake less going forward.

Some other notable observations, my NO3 and PO4 dropped slightly for today's test. Not unexpected as some of the I is certainly going to accelerated macro growth.

I am also seeing the barest of polyp extension on a duncan colony that I have been watching. This particular colony ended up in deep, deep shade for a few months when overshadowed by an out control monticap. When I rescued it and moved it back out into the light, it had a hint of poly extension, but that disappeared after a week or two and showed none for several weeks. This morning, after yesterday's iodine dose, the meager polyp extension is back. Let's hope that continued iodine dosing has a positive impact on it.

I will test again tomorrow and start thinking about a manual dose and test strategy while I establish a good plan for automating it.

 

[Randy Holmes-Farley Verified Community Expert]

Hmm, I am wondering if the speed of uptake is driven by an accumulated deficit? Meaning after establishing daily supplementation

It's possible, certainly. Iodine is not really used for growth (like N and P), but by other sorts of processes and it's not known how the uptake varies with concentration.