Salt study

[ccCapt]

AquariumWaterTesting.com did a test on a bunch of the most popular salts used. Here are the results of the study. It's sort of hard to decipher. I use Red Sea Coral Pro and I think those results look good.

There is a thread on RC about it here.

 

[Kurt_Nelson]

As noted on the RC thread, it's really a shame that they didn't mix up the samples so they all had the same salinity. I can't fathom why they didn't... you can't really use the results directly without scaling them to NSW salinity levels.

Thanks for the link though! Good info to have. (Looks like the "bad batch" of RC was still out there when the test was done. Think I'll just sit tight on my "good bucket" and wait a while to order another one!)

 

[fijiwigi]

Wow very interesting and I thought my salt was Nitrate and phospate free. If I read the link correctly all of the salts have trace amounts of the bad stuff. The thread on ReefCentral talks highly of the Coralife salt. I debated that salt in the beginning but decided to go with reefcrystals because it seemed to be the favorite.

 

[Kurt_Nelson]

It's always a good idea to test your new salt water from time to time, just as you'd test your tank water. "Nitrate-free" is a somewhat relative term, I think. Kind of like "fat-free foods". It's "fat-free" and can list on the label "0 g fat" as long as it has less than 0.5g of fat per serving. Nobody says what the serving size needs to be!

 

[cmor1701d]

Great study, BUT the graphs are meaningless. The SG was different for every brand. They mixed 7g per 200ml RODI water. They did not mix to 35ppt SG so the comparisons can not be made unless you extrapolate numbers for each test of each salt at 35ppt.

 

[MarineFlake]

"...As noted on the RC thread, it's really a shame that they didn't mix up the samples so they all had the same salinity. I can't fathom why they didn't..." / "...They did not mix to 35ppt SG..." You are mixing terminology. Mixing to a SG and testing was not the point of the test. The goal was to measure the amount of elements, believed important to us aquarists, in a given, quantified amount of mix.

"For example, 35 ppt value simply means 35 parts per thousand. If you broke down the water into all it's parts, out of a thousand of those parts, 35 would be salt (sodium chloride). Another way to think of it is simply 3.5%.

The 1.026 sg value is a little trickier. The sg stands for Specific Gravity. Specific gravity is not so much a measure in units, as it is a measure of density as compared against pure water. Pure water has a Specific Gravity (density) of 1.0. SG is a quick way to guestimate the salt content of your water. It is not always the most accurate way, however.
In practice, either value is intended to give you a measure of the concentration of the salt content of the water.
One common mistake made early on, is not taking into consideration the affect temperature has on salinity. Since temperature will make the water expand/contract, as a result, this will affect the density of the saltwater. There is a decent chart that can be found here, which will show the changes in salinity due to temperature." ( The Reef Tank - Powered by vBulletin ) If you consider the goal, which is to compare how much of each element is found in a given, standard sample, than you can conclude that mixing to a given SG is not productive as mixing to an unquantified sg will skew the amount of elements found in any given sample. The quote, however, does raise a *very* important point regarding temperature, which I do not see stated anywhere in the PDF. I do not know that temp would affect the element measurements, but it would have been nice to notate.

HTH, Enjoy!

 

[melosu58]

Thanks for the info. Very informative.

 

[cmor1701d]

Most of us mix to an ATC-refractomer reading of 35ppt. It is at this level that we test for water parameters. Knowing that x grams of mix mixes to a y ppt of salinity tells you how much mix of each brand you need. In other words, does a 200 gallon bucket actually make 200 gallons of salt water mixed to 35 ppt using a temperature compensating refractometer.

I then want to compare the amount of trace elements in a sample of salt mixed to NSW (35ppt). That is what the goal of the test should have been. This test did not accomplish that.

 

[Kurt_Nelson]

Most of us mix to an ATC-refractomer reading of 35ppt. It is at this level that we test for water parameters. Knowing that x grams of mix mixes to a y ppt of salinity tells you how much mix of each brand you need. In other words, does a 200 gallon bucket actually make 200 gallons of salt water mixed to 35 ppt using a temperature compensating refractometer.

I then want to compare the amount of trace elements in a sample of salt mixed to NSW (35ppt). That is what the goal of the test should have been. This test did not accomplish that.

Yeah... what he said!

But in reality, the test did accomplish that. You just have to get out the calculator and scale the numbers yourself. They should be linear.

 

[cmor1701d]

Kurt,

I agree, but the charts and graphs should have been scaled for that. Otherwise you can't really compare one salt to another the way we would use it. To show a chart for conductivity of 7 grams of mix in 200 ml of water and compare it to NSW is meaningless. To prepare the samples to 35 ppt salinity and then compare it to NSW would be meaningful.

If I had the time I would make the calculations and post new charts. New job starts tomorrow so I won't have the time. At least I have a starting point which something I didn't have before this study.

 

[Kurt_Nelson]

Kurt,

I agree, but the charts and graphs should have been scaled for that. Otherwise you can't really compare one salt to another the way we would use it. ...

I haven't followed the thread over on RC, so maybe this has come out over there. Either way, I figured I should post this here so others have the info if they come across this thread later on.

It appears - even though it's not stated anywhere in the report - that all the ion charts, except for salinity and conductivity, were done with 35ppt water. So the salinity was equalized across the different samples. Don't know exactly how they did this, as nothing to this effect was stated in the report. I got this info from a reliable source (Boomer) over at Reef Frontiers. I normally don't like cross posting of messages between boards, but since you have to register over there to view any post, I'll copy/paste the conversation I had with him...

Quote:

[original question] Therefore I think it should of been tested at 35ppt instead of a determined weight. IMO I may be missing something completely!

{Boomer's response]

Yes you are, two thing missed.

1. Weight is done and should be done to see how much water is in the salt, i.e., 35 grams in 965 grams of water and the Salinity ** should = 35 ppt but you measure the salinity and it is only 31 ppt, thus there is 4 ppt water you are paying for

2. The assay they did was misunderstood by many from the way they wrote it. The actual ions measured where all done when all salts were actually at 35 ppt.

[Kurt's question]

Sorry for the off-topic drift, but a quick question about (2) above...

I understand your comment in (1) and why they tested the way they did... so you could see how much water you were buying. And that's shown in their first chart showing salinity.

But nowhere in the study did I find them saying anything to even hint that the rest of the charts were done with all the samples at 35ppt. I can understand why it was "misunderstood by many..."! Am I missing something, or are you just aware of additional information that wasn't published?

[Boomer's response:]

Kurt they dropped us (actually DR.) an e-mail to inform us of that, due to the posts on RC I would assume. It stated, in so many words, that the ion measurements where all done on salts that were normalized to 35 ppt. Only the Salinity and Conductivity gave different salinities due to the weighted 35 grams. At first we all thought as you

as it was not stated anywhere, just as you posted. What bother me Chris and Randy is they really say nothing about their methods. And look at some of the odd ball ion levels like the Ca++ in IO

I know of no one ever, in the history of IO, that has ever measure Ca++ that high in a sample test, i.e., + 500 ppm

 

[cmor1701d]

Thanks for posting that Kurt. I'm going to head back to RC for follow up. If we can confirm that most tests were done at 35ppt then the report is fabulous. I just wish they used a larger sample size.

 

[ccCapt]

What they did was 1st take the same amount of salt from all brands and add it to the same amount of water and check the SG. This way you can see how much salt you really need when mixing a batch yourself.

Then they dumped those samples and made all new samples of each salt all mixed to 35 ppt and then started testing.