Experiment: Trace Element Limitation in Reef Tank?

[Randy Holmes-Farley Verified Community Expert]

Question. Could the use of Prime water conditioner (say a ml or so) have any effect on the availability of some metals?
"Detoxifies heavy metals" means it binds them to keep them away from biological processes?

That is the presumption, but they do not reveal ingredients.

 

[Ardeus]

This thread has helped to make some decisions and I made a video about it:

 

[taricha]

That is the presumption, but they do not reveal ingredients.

Prime is based on hydrosulfites, it is a chemical reducer, not a chelator. Its effect is short-lived, perhaps no more than two days ...

The reason I ask this about Prime is that during the time between when diatom presence, algae growth, and sand pigmentation was lowest (around day 14) and when I noticed those things make a move back the other direction (toward day 24) I did nothing that I thought could have added back scarce resources.
But within this time frame (I wish I had better notes) I changed two things that I thought may REDUCE likelihood of adding scarce resources.
One was stopped food that had vitamins enrichment (marine cuisine, and brine with spirulina) and replaced with frozen daphnia and cyclops in packaging that claimed nothing added. The daphnia I was already using occasionally, but Cyclops is a food I hadn't fed in weeks.
The other change I made is that I stopped using tap water as evaporation top off. I switched to store bought distilled water jugs.
Both of these changes seemed not possible as sources for increased scarce resource inputs... but when I was using tap water - I was adding Prime daily - which may have been somehow reducing the ability of organisms to get at the scarce heavy metals in the water. When I switched to distilled, no prime was added after that.
This still seems implausible, but at least it's a mechanism in the direction of explanation.

 

[Jose Mayo]

The reason I ask this about Prime is that during the time between when diatom presence, algae growth, and sand pigmentation was lowest (around day 14) and when I noticed those things make a move back the other direction (toward day 24) I did nothing that I thought could have added back scarce resources.
But within this time frame (I wish I had better notes) I changed two things that I thought may REDUCE likelihood of adding scarce resources.
One was stopped food that had vitamins enrichment (marine cuisine, and brine with spirulina) and replaced with frozen daphnia and cyclops in packaging that claimed nothing added. The daphnia I was already using occasionally, but Cyclops is a food I hadn't fed in weeks.
The other change I made is that I stopped using tap water as evaporation top off. I switched to store bought distilled water jugs.
Both of these changes seemed not possible as sources for increased scarce resource inputs... but when I was using tap water - I was adding Prime daily - which may have been somehow reducing the ability of organisms to get at the scarce heavy metals in the water. When I switched to distilled, no prime was added after that.
This still seems implausible, but at least it's a mechanism in the direction of explanation.

Prime is excellent as an immediate-use conditioner in the preparation of water. But its effect is only temporary; what he now hijacks, releases later.

A practical way to observe this short effect is to prepare a small batch of water with Prime and then prepare a few milliliters of potassium permanganate solution, which turns purple. Adding this permanganate solution to the water with Prime, the immediate loss of staining should be checked, which indicates that Prime neutralized the permanganate ... two days later, returning the permanganate solution to the same water treated with Prime, will not see the effect of discoloration.

Regards

 

[taricha]

So while I wait another couple of days for system to finish re-stabilizing - here's methods I've been looking at to improve measurements.
1. Played with ph calibration using new batches of 7.01 and 10.01 reference solutions and checked versus other known samples, make sure I'm finally doing this right - after calibration meter is reading within +-.02
for details on homemade ph solutions. https://www.reef2reef.com/index.php?posts/2490342
2. With my well calibrated PH meter I tried the DIY alk test itself
https://www.reef2reef.com/threads/diy-alk-test-discussion-thread.186606/
and it is SO easy and such an improvement on the test kit. All you need to know is pH, a measured volume of tank water, and a measured small volume of standard acid.
I wandered around to see what I could find in the forgotten closets and boom...

volumetric flask and titration tube thingy.
Did it with two samples. (One I overshot and so I added 5ml more of tank water to get back up to 4.50 pH.)
Got 8.317, and 8.344 - awesome!
Btw, using a plunger syringe from test kit I got 8.40 - fine, but I'll probably use titration tube when I can.

3. I found a colorimeter in another closet. 4 wavelengths 430,470,565,635. The 565 works pretty well for checking the pink of my NO3 test kit.
I also got a seachem iodine kit, and I'll see if the red 635nm can give me decent readings on the shades of blue in the kit.

4. All of that awesomeness aside, using the volumetric flask and a delicate scale i checked my hydrometer and found I apparently mis-marked it years ago and have been aiming for a target salinity of 1.021 all this time thinking it was 1.026
oops.

 

[Randy Holmes-Farley Verified Community Expert]

4. All of that awesomeness aside, using the volumetric flask and a delicate scale i checked my hydrometer and found I apparently mis-marked it years ago and have been aiming for a target salinity of 1.021 all this time thinking it was 1.026
oops.

What did you weigh out?

 

[taricha]

What did you weigh out?

I found that my 500ml volumetric flask weighs 510.6 grams more with water in it than empty.

 

[Randy Holmes-Farley Verified Community Expert]

I found that my 500ml volumetric flask weighs 510.6 grams more with water in it than empty.

Couldn't the scale also be off?

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, that gives you density, not specific gravity.

 

[Randy Holmes-Farley Verified Community Expert]

At 25 deg C, that gives a sg of 1.024

 

[taricha]

Nah. I used one of those analytical balances with the windows you've got to open to get into it. I also checked It versus known masses. It tells me more digits after grams than I know what to do with.

I think when I made the original "correction" on my hydrometer, I made it in the wrong direction.

Couldn't the scale also be off?

 

[taricha]

Bigger discrepancy than I expected.
I took your ballpark instructions (weigh 513g and call it 500ml) and assumed it was more precise than it was.

At 25 deg C, that gives a sg of 1.024

 

[taricha]

revisiting the salinity thing.
I re-read the salinity calibration article to see what I've forgotten. Mostly that SG and density differences are significant for us. And that couple of years ago when I set the target line on my hydrometer, It wasn't based on 1.026 - it was 35.0 psu (ppt).
I re-did it with more precise scale to check my work.
aiming for:
NaCl weight concentration 3.714 % = 1.02660 SG = 35.0 PSU
7.428g Salt added to enough water to total 200.0g
mixed for some 30+ min, temp matched to tank water both 25.5-26 C.

new mark at the pointer in green. old mark is halfway between the "1.024 & 1.023" - so really it wasn't as far off. Maybe poor job dissolving originally, or used an inaccurate volume beaker for the water first time.

So I mostly just confused myself with a few small errors - the largest being density / sg conflation.

 

[taricha]

As I think about restarting data collection in a couple of days, I'm debating which approach gives me the best chance at what I'm aiming to show...

A. Keep inputs rock solid same every day - track tested nutrient levels and infer consumption from changes in levels.
or
B. Adjust inputs daily to keep tested nutrient levels rock solid same - Infer consumption from the daily inputs.

Some things obviously make more sense to do one or other. I'm going to feed the same amount every day, and my tiny carbon dose won't change so those fall under A. Obviously Alk/Ca needs to be kept at target levels to avoid confounding every other variable, so those go in B.
like Randy said early on pH should be kept even. I plumbed skimmer to outside and upgraded a fuge light, so hopefully my pH stays solid - and I think it is. If not- I don't know how I could move pH to a target level if it was off. Maybe switch from 2-part to kalk (or a sliding scale mix of the two) if I need to bump pH back up? That may introduce more variability than what it's meant to solve.
(aside:I think my pH calibration doesn't hold. My meter is within +-.02 on the day of the calibration and +-.10 the next day. I'm storing it in the pH7.01 buffer as instructed. I dunno what I'm missing. I'll keep running out of buffer real fast if I need to recalibrate daily.)

So I guess I'm thinking about N, P, and Si. Route B is probably a clearer demonstration of what I'm aiming for, but it may be impractical from error standpoint to change daily doses based on test level.

 

[mcarroll]

(aside:I think my pH calibration doesn't hold. My meter is within +-.02 on the day of the calibration and +-.10 the next day. I'm storing it in the pH7.01 buffer as instructed. I dunno what I'm missing. I'll keep running out of buffer real fast if I need to recalibrate daily.)

Is the probe possibly just worn out?

 

[taricha]

Is the probe possibly just worn out?

Nah, The ph meter is brand new. Like a month old.

Edit: actually, although the resolution is 0.01, the stated accuracy is +-0.10.
When I have just calibrated, it's definitely better than that, but I guess short of a fresh calibration every day, that's what I'm gonna get.

 

[taricha]

So some data here. I decided to target specific values, track as precisely as possible the actual input of all nutrients and dose varying amounts in order to hit those targets.
Precise nitrate test numbers discussed here: https://www.reef2reef.com/threads/accurate-no3-test-with-hanna-ulr-p-checker.387586/

So this all allows me to get a peek at the actual variable I want: Nutrient consumption.
Here are my targets:
PO4 - 0.080ppm
No3 - 6.0ppm
Si - 0.80 ppm
Ca 420
Alk 8.5
pH 8.0 (at lights on)

All nutrients are plotted here as a percent of these respective target values.
The first week was spent mostly homing in on targets. Ca needed the most significant movement.

Again, P, N, Si erratic for the first week, but better after.

Interestingly, I didn't expect N, P, and Si consumption as a percent of their targets would be around the same order of magnitude, but they are - generally averaging 30-40% per day consumption in my system.

To get consumption numbers to look more sensible, averages over 2 and 3 day windows gets used.

And Finally, Ca and Alk consumption. Despite thorough treatment in randy's article on Ca/alk "imbalances" that arn't really, I was one of those who would have sworn that my tank eats way more Alk than Ca (at one time - I dosed 60% Ca vs 100% alk), but it's funny how consistent measurement and aggregating data over time reveals reality.

Since obviously they aren't depleted at same percent rate of their target values, I plotted them as percent of their average consumption.
My average Alk 0.50dkh:Ca 3.05ppm per day starts to look a lot closer to the 1.4 dkh per 10ppm Ca ratio that it's supposed to be.

 

[taricha]

The TLDR version of the above post: I found average consumption of major nutrients in my system.

These consumption rates are now my baseline levels. If consumption of most or all of these nutrients falls and stay significantly below these baselines, while the major nutrients are kept at target levels, then I'll conclude a limiting resource (trace element) is at play.

I will then dose trace elements to see if the consumption returns to/exceeds baselines.

 

[taricha]

So, seems to be great consensus that Iodine in a reef tank is depleted "rapidly"
I'm curious what "rapidly" means in my very mixed reef.
Based on these seachem instructions...

BEGINNER: Add 5 mL (1 capful) for each 200 L (US 50 gallons) every other day.

ADVANCED: Add 1 mL for each 80 L (20 US gallons) daily to raise iodide by 0.10 mg/L. If necessary, adjust amount so that iodide reads 0.06–0.08 mg/L 6–12 hours after the last amount. Thereafter, use this amount daily and check iodide twice a month.

(Seachem's product is 8mg per gram.)
The beginner directions imply that a concentration of .02ppm would be depleted in under 2 days. So >.01ppm per day.
The advanced directions imply a drop of at least double that >.02ppm in under a day, but leaves open the possibility of consumption several times that amount.

Either way, they seem confidant that any iodide concentration on the order of natural sea water would be depleted under a week and maybe as quickly as a couple of days.

Based on this thread,
https://www.reef2reef.com/threads/iodide-test-seachem-kit-and-hanna-silica-meter.391003/

that ought to be pretty straightforward to check.

 

[Randy Holmes-Farley Verified Community Expert]

So, seems to be great consensus that Iodine in a reef tank is depleted "rapidly"
I'm curious what "rapidly" means in my very mixed reef.
Based on these seachem instructions...

(Seachem's product is 8mg per gram.)
The beginner directions imply that a concentration of .02ppm would be depleted in under 2 days. So >.01ppm per day.
The advanced directions imply a drop of at least double that >.02ppm in under a day, but leaves open the possibility of consumption several times that amount.

Either way, they seem confidant that any iodide concentration on the order of natural sea water would be depleted under a week and maybe as quickly as a couple of days.

Based on this thread,
https://www.reef2reef.com/threads/iodide-test-seachem-kit-and-hanna-silica-meter.391003/

that ought to be pretty straightforward to check.

In my tank, it meant that I could dose to NSW levels and find none detectable by kit within a week, probably much less. That was the basis for my dosing: once a week to NSW seems a good dose even without measurement.