Instant Ocean high magnesium

madweazl

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Mixed up 10g of Instant Ocean for a water change prior to heading out of town. I always test the water in the tank prior to doing a water change and was going to skip it today since I just tested it on Sunday but decided to go ahead and do it regardless. To my surprise, the magnesium was 1500 (I generally keep it in the 1350 range but it has been creeping up), up from 1440 on Saturday. Salinity in tank was a bit low (on Saturday) so I mixed up a gallon of Instant Ocean and added it to the ATO to bring it back up gradually over the course of a few days.

After testing the display, I check the freshly mixed water that has been circulating for about 14 hours.

Salinity - 34.5 (1.026)
Alkalinity - 7.3 dKh (3ml muriatic acid to 5g bucket)
Calcium - 500+ (full color change was a few drops away so I didnt bother taking it to full color change, estimate 510-515)
Magnesium - 1695

I mixed up approx 3/4 gallon of water after thoroughly mixing the bucket of Instant Ocean (rolling it around the floor for a while) and used it as a control of sorts.

Salinity - 34.5 (1.026)
Alkalinity - not tested as it was within normal range
Calcium - 410
Magnesium - 1680

With the large delta, I decided to test the 5g bucket that I had mixing again.

Calcium - 500 (close enough to the results I had initially)

Tested the freshly mixed 3/4 gallon again.

Calcium - 500

Ok, I have a large delta on one of the tests for some reason (likely user error) but of note, the calcium and magnesium are considerably higher than I've ever had with Instant Ocean. Over the past year and a half (give or take some months...), it has typically been:

Alkalinity - 10.8 dKh (prior to addition of muriatic acid)
Calcium - 435-445
Magnesium - 1365-1380

It looks as though I've been mixing it well enough in bucket to mitigate any separation but the levels of magnesium are way out of the typical range and well beyond anything I've ever measured in my tank (I'm usually pretty consistent though the test above certainly illustrates something wonky).

Here are some historical plots from my Aquatic Log entries:

Calcium
43806375061_9e30d5991e_b.jpg


Magnesium
29936679598_1e2d3b9cbf_b.jpg


Both had been trending upward but I didnt pay much attention to the calcium because I'd mixed up a new batch of two part around the same time I purchased the bucket of salt; I figured it was likely I mixed it up slightly different from the last batch so I was just going to adjust the dose to offset it. I didnt have a theory on the magnesium but the results were so much higher today I had to investigate further.

ATI ICP results from sample taken 27 Jun 2018. Below are my results followed by ATI's; samples were taken at the same time.

Salinity - 35ppt ATI - 35.91
Alkalinity - 7.4 dKh ATI 7.18
Calcium - 395ppm ATI 428
Magnesium - 1350ppm ATI - 1426

ATI ICP RO/DI results from the same sample.

I'm on the phone with Instant Ocean (Tetra) trying to track down the lot number to see if we can figure something out. I'll update if/when they're able to provide any information.

Lot # 18081

Edit: Just got off the phone with customer service. They were pleasant to deal with and noted the lot number but did mention they would not contact me regarding any results they found in house unless it was something recallable. They asked a few questions and are sending out a bucket of salt (said to expect arrival in 7-10 days). Also, they advised hanging onto the receipts for salt purchases.

The lot # is printed on a small tag on the lid of the buckets but may be different for bags/boxes.
 
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Randy Holmes-Farley

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Which test kit? Many folks have issues with the Red Sea magnesium kit.

Which Instant Ocean salt mix? The normal IO does not typically have substantially elevated magnesium.
 

Tony Thompson

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Hi @madweazl , I had come across this problem of creeping Mag in many comments from fellow reefers and online comments, with different salt brands. The worst affected seem to be those brands with elevated Mag in the first place.

A big part of the hobby for me personally was to try and test products against the manufacturers advertised statements. I am by no means a qualified chemist, nor do I have a certified lab, but being a hobbyists myself I was interested in trying to determine how the figures added up using readily available equipment. I did of course put in place certain controls to try and reduce any margin of error.

In a number of salts I did find creeping Mag. When the salt brand was near to NSW levels, the deviation was negligible. I spoke to the manufacturers directly but not one of them seemed to want to discuss anything except my own possible testing failures. Most did also mention settlement in the bucket.

In my experience , decanting and rolling did not seem to alter the deviation errors significantly. Infact I wondered if this rolling may actually increase settlement. However the only successful procedure that I found effective was to buy smaller volumes of salt and mix up the whole box in one go. I also remember looking at toxicity levels for Mag in a number of research papers, If I remember correctly the amount of Mag needed to become toxic or at least significantly affect the type of animals we generally keep in aquariums was way higher than we would expect to see from hobby salt mixes. That said, I did find it a little concerning that after all my efforts to keep my parameters stable, this element in particular did not want to play game.

For my own use, I now use a brand of salt that is very close to NSW levels with regards the main params. If I wish to elevate these params I can always do this manually by adding the elements to the water mix separately before adding to the tank. This way I find I have much greater control over stability.

I remember my woodwork teacher at school always used to say , always cut the wood a little to long, you can never cut a bit on but you can always cut a bit off.:). I take the same principle with my salt. I can always add a bit of a certain element but its much harder to try and take a specific element out.
 

cracker

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I have to agree with Randy, I get crazy readings from my redsea mag test every so often .
 
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madweazl

madweazl

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Which test kit? Many folks have issues with the Red Sea magnesium kit.

Which Instant Ocean salt mix? The normal IO does not typically have substantially elevated magnesium.

Regular old Instant Ocean. I use Salifert for magnesium levels but the ATI ICP also shows approx 1425. This tank was moved at the end of May and got a 100% water change using Instant Ocean but the issue didnt arise until the latest bucket of salt (shortly after the move). I'm out of town for another week but the salt Tetra sent to replace it arrived today so I'll test it when I get back. Lot # 18120 on the new arrival.
 

Randy Holmes-Farley

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Regular old Instant Ocean. I use Salifert for magnesium levels but the ATI ICP also shows approx 1425. This tank was moved at the end of May and got a 100% water change using Instant Ocean but the issue didnt arise until the latest bucket of salt (shortly after the move). I'm out of town for another week but the salt Tetra sent to replace it arrived today so I'll test it when I get back. Lot # 18120 on the new arrival.

1425 ppm for magnesium is fine. :)
 

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