Today on BRStv Investigates, “How long can you store your mixed saltwater?”
Hi, I’m Randy a host for the YouTube series BRStv Investigates where we take popular reefing
theories, methods, questions, & products and dive even further than what the manuals and
packaging will tell you; in order to put them to test in real world environments; rate them
on our scale of reef fantasy to reef certainty and share with you, the reefing community,
what we find.
Today we continue our testing of some of our most popular salt mixes, by answering the
common question of, “Will Alkalinity and Calcium levels in freshly mixed saltwater
drop or precipitate during storage?”
Meaning that if I chose a specific salt brand based on the levels for Alkalinity and Calcium
they provide after mixing a batch to my target salinity of 1.026 Specific Gravity or 35parts-per-thousand;
how long can I store that batch of saltwater and trust that those levels won’t shift
to the point that I would need to adjust them back?
So, for those reefers who are making small batches of water and using it rather quickly
after mixing, worrying about the Alk and Calcium parameters shifting is likely less important
to you.
However for a growing number of reefers who like to mix larger batches less frequently
and use over longer periods of time or for those who are using stored saltwater in auto
water change bins, it would definitely be nice to know if your salt mix’s Alkalinity
and Calcium were stable from beginning to end.
In order to determine just what happens to mixed saltwater over time during storage,
we plan to test the same eight most popular salts on our site that we used in our test
for cost per gallon; with the Tropic Marin Pro and Classic; Brightwell NeoMarine; Red
Sea Coral Pro and Blue Bucket; HW Reefer; and both Instant Ocean Standard salt and Reef
Crystals.
We’ll mix up 20gallons of each salt brand to the most commonly targeted 35parts per
thousand or 1.026 Specific Gravity; and take their initial batch readings immediately after
mixing, two hours later, four hours later, at a full 24 and 48hrs, and also at the 1,
2, and 3-week storage mark.
In order to remove outside variables like temperature and water circulation, we plan
to only mix each batch of saltwater until they are visibly clear at a room temperature
of 67-degrees, then leave them loosely sealed without further circulation and heating …much
like storing the saltwater at room temp in a loosely sealed container like a Brute Trashcan
with a lid.
The biggest thing to note here is that for these tests we are using the same type of
hobby grade test kits that many reefers also use at home, so there should be some expectation
of accuracy margin with their results which will probably be in the plus/minus 1/2-a-dKH
point for Alkalinity and about plus/minus 10-15 parts per million in calcium.
This accuracy range and margin for error are within the test kits accuracy range with some
added room for minor procedural inconsistencies and subjective endpoint readings and due to
that we’ll likely see some type of fluctuations in the results, but I expect the answer will
still be clear regardless and end up providing us with a window into some of the same readings
you would get at home, using the same test kits and procedures.
Let’s start looking at the results of this test by starting with the changes in Calcium
for each of the eight salt mixes, which as you’ll see don’t really tell a jaw dropping
story when looking at the overall change for each salt and most are within our plus/minus
10-15 part per million testing margin and some even tighter than that.
Again, I’d note that this is a hobby grade test kit that uses a color change indication
as to the concentration levels in the sample, so we do have to reasonably expect that the
end point is going to be subjective based on methodical testing procedure and individual
interpretation of the exact moment the reagent causes a full change in sample color.
Before we get too far into the results, I wouldn’t expect to see a substantial drop
in Calcium due to precipitation, because calcium is more abundant in the water column versus
Alkalinty to the tune of about a 7 to 1 ratio.
Meaning that for every change up or down in one full dKH point, on average the Calcium
would only change about 7parts per million…so pretty insignificantly in comparison and likely
why Alkalinity will be the more determinative factor when showing swings throughout the
duration of storage.
Starting with the Tropic Marin Pro results we see that immediately after mixing we get
a start point at 400ppm and at the end of three weeks in storage it ends just 10parts
per million from that start with a reading inside of our 10-15ppm margin range of 410parts
per million calcium.
The average of the readings ends up being 413ppm and what I would consider to be a negligible
or zero change.
The Tropic Marin Classic salt ended with similar results over three weeks, with a starting
point of 400parts per million and ending at 415 and still within our margin for error
for hobby grade testing.
Along with that and similarly to the Tropic Marin Pro we see an average of only 411, leaving
this salt pretty much unchanged over the entire testing period.
Brightwell NeoMarine is up next and again, we see a pretty flat set of results starting
with 390ppm calcium and ending at 400, with the overall average coming in at 393 which
is only a surprising 3parts per million deviance from the start point.
HW Reefer showed slightly different results than the previous three, testing at 450ppm
right after mixing and ending 25parts per million lower after three weeks at 425; which
is about an overall drop in calcium of 10parts per million when factoring out our 10-15ppm
margin of error and pretty darn close to being another salt mix that seems to hold steady
over time.
Let’s take a look at the Red Sea Blue Bucket next, which tells a similar tale to the previous
salts with a 400 start point and 410 end point, for an overall deviation of less than our
margin of error.
The overall calcium results are pretty close to identical as the Tropic Marin Pro in starting
and ending points, as well as an average of the same 413ppm throughout the testing period.
Red Sea Coral Pro is next and right away we notice the first pretty noticeable drop in
calcium where right after mixing we see an initial reading of 495 and after three weeks
an endpoint leveling out around 430 for an overall change of 65parts per million.
The largest difference in calcium comes within that initial 4hrs with a fall from 495 to
440, and given that Coral Pro is absolutely an elevated salt mix it’s probably not surprising
to many reefers that with elevated levels of Alkalinity and Calcium both, we see some
noticeable drop due to precipitation shortly after mixing and also likely why Red Sea themselves
recommend mixing for 30mins to 2hrs, but no more than 4 total.
The results for Instant Ocean Standard are roughly on par with a majority of the other
salt mixes tested, with a 400ppm start point and a 385 end point, which gives it an average
of 387 parts per million and the lowest overall calcium level out of the group, likely due
to the two relatively low readings that came in at 375parts per million.
Rounding out the Calcium testing is the Instant Ocean Reef Crystals that states has purposely
elevated Calcium levels and shows in the testing where it started at 500parts per million and
ended 10ppm lower at 490, with an average across all points at 489.
Moving on to Alkalinity, where we’ll likely see a clearer picture as to how each salt
holds up to storage as changes in dKH are more noticeable over Calcium likely due to
its lesser availability in the water column where more subtle changes should be easier
to see.
Again starting with Tropic Marin Pro we see almost a completely flat line over three weeks
of storage with the Alk starting at 6.9dKH right after mixing and only fluctuates a maximum
of 3/10ths of a dKH point throughout the entire test, which is well under our 0.5dKH testing
margin.
Tropic Marin Classic shares a somewhat similar path beginning with 8.9dKH Alkalinity and
ending 2/10ths higher at 9.1.
The largest swing overall was a difference of 0.6dKH from the lowest test at 8.6 to the
highest at 9.2, but when we factor in the 1/2 dKH point for testing margin, the overall
change comes out to only a 10th of a point and not really any significant change at all.
Much like the calcium test, Brighwell NeoMarine looks to have the least amount of overall
change, with a starting point of 7.7 and an ending point of 7.8, and throughout the entire
3week period only changed in Alkalinity by a pretty surprising 2/10ths of a dKH point.
HW Reefer wound up being another well performing salt when it comes to maintaining parameters
through storage where it starts at an 8.7dKH and ends just a tenth higher at 8.8.
Much like the Tropic Marin Pro, the overall change from HW’s lowest to highest reading
is only 3/10ths of a dKH.
Let’s take a look at the Red Sea Blue bucket salt mix which shows a slight drop in Alkalinity
from its starting point of 7.9 to the end point of 7.3.
We do see a slight increase peak at the 48hr mark where it hit 8.3dKH, which is difficult
to explain but still within our 0.5dKH margin of testing, but does come back down after
2weeks of storage and ends with a 0.6dKH difference from beginning.
The Red Sea Coral Pro again shows the largest change across the salts we tested with the
highest start point of 11.0dKH and ending with a drop of 2.2dKH total at 8.8dKH.
Again we see a slight increase at the 48hr mark as we did with the Blue Bucket, but as
for the drop of alkalinity in general, I’d say that this is actually the type of performance
that could be expected from elevated levels where the water is super saturated with Alkalinity
and Calcium which probably should fall over time and likely why Red Sea openly provide
very specific mixing instructions where you mix the salt unheated at around 68-degrees
and for 2hours at max (absolutely no more than 4hrs), then heat to match tank temp then
use making it a good option to use in a shorter period of time.
Looking at Instant Ocean Standard again we another salt with slightly elevated levels
of Alkalinity, which starts at 10.1dKH immediately after mixing and ends surprisingly higher
at 10.4 or 3/10ths higher.
Overall, from the lowest reading of 10.1 in the beginning to the highest of 10.6 at the
2week mark we see a 0.5dKH increase, which is within our testing margin, but still hard
to explain.
Similarly to the Red Sea Coral Pro the Instant Ocean Reef Crystals shows purposefully elevated
levels for Alkalinity and Calcium, however for the Reef Crystals the Alkalinity doesn’t
fall but actually also seems to increase over storage (much like the IO Standard did) from
a start point of 10.6dKH to an end point of 11.0.
Again it is hard to explain how the levels can climb, although it is within our testing
accuracy range, but both Instant Ocean salts performed remarkably similar to each other
with their levels increasing.
Even harder to explain is how Reef Crystals is able to maintain higher Alkalinity and
Calcium without any type of measurable drop in both parameters that would indicate precipitation.
Ok, so to answer today’s question of “Will Alkalinity and Calcium levels in freshly mixed
saltwater drop or precipitate during storage” I’d actually rate this one 2 on the reef
fantasy scale because it is pretty obvious to me that really most of them can be stored
without issue; especially if left uncirculated and unheated as we did.
Really the only outlier here is the Red Sea Coral Pro salt, which seems to follow the
expected path of results that one would guess when using salts with purposefully elevated
levels, yet I believe Red Sea would recommend not storing it for longer periods of time.
Alright, what does this mean for the average reefer who’s looking to make larger batches
of saltwater that will be used periodically for smaller percentage water changes or in
an Auto Water Change situation like we use here at BRS for our BRS160, Reefer 750XXL
and Ryan’s office tanks?
Really based on the storage conversation alone, I’d be comfortable picking most of these
salts and know that I can expect the same levels from the time it was initially mixed
to the time I finally got around to using it or while it is being dosed slowly over
a longer period of time from my auto water change reservoir.
As long as we are able to mitigate evaporation by keeping my reservoir loosely closed and
likely out of large temperature changes, pick salt that matches your desired perimeters
and it will likely hold for you.
So what’s next in salt testing BRStv Investigates episodes?
Well for those who require larger percentage water changes where, not only are matching
parameters for Alkalinity and Calcium of their display tank important, but also matching
the temperature to reduce a larger fluctuation being equally as important; we plan to take
this test even further by running the same experiment, but in a temperature controlled
tank at 78-degrees with the addition of circulation to find out if and how heat and flow affect
the same Alkalinity and Calcium parameters for each of these salt mix brands, in an effort
to determine whether some these are cleaner than others or more or less likely to precipitate
crust in the tank?
Lastly, this wouldn’t be the regular Friday BRStv episode without something to give away;
so this week we have two Hanna Instruments Professional Reef Test Kits up for grabs,
each valued at 230-bucks, so click that link in the lower left or head over to the site
and click free prizes to sign up to win.
Finally, head on over to our Reef2Reef post and vote on today’s poll asking, “How
long do you store your mixed saltwater?”
I’m interested to see if some decide to start storing theirs a bit longer.
Stay tuned as we continue to explore and test even more reef myths and reef certainties
around salt mixes and if you have anything you’d like to see us test or questions about
salt mixes in general, drop a comment below, share your ideas on our reef2reef thread,
or better yet jump on our #AskBRStv FB group where the BRS crew including Ryan and I get
in there and answer your questions.
See you on the next BRStv!