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Unread 01/29/2010, 08:35 AM   #1
timdanger
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best way to substantially raise Mg

39g display tank, total system volume is probably about 45g with the sump/etc.

so, my LFS recently tested my Mg to be 1000ppm (Elos test kit), and as a result, my Ca has been hovering between 360-380ppm and my Alk has been about 8dkh (i've been testing both of those every day with Elos test kits). No idea how that number got that low. might be the salt (i buy pre-mixed water from the LFS).

to deal with this, i had about 250g (approximately) remaining of Seachem Reef Advantage Magnesium (dry), and I proceeded to add the entire bottle over the course of 3 days. based on the math provided on the seachem bottle (i haven't tested to confirm yet), that really isn't going to have raised my magnesium as much as I would need.

i tried to add about 20ml of the liquid calcium component of my 2-part (brightwell reef code A) last night to see if i could get that calcium number any higher at all. i added it with a turkey baster right into the path of my vortech, and it seemed to precipitate out a lot of what i'm assuming is calcium carbonate.

so (again without testing), i'm taking this to mean that my Mg really isn't high enough to raise my Ca, and i need to do something to get that number up. here is the dilemma: i paid $10 for the bottle of Seachem Mg that didn't apparently raise my Mg enough to even add Ca without producing flurries of calcium carbonate.

so, i have a couple of options:

1) buy a larger quantity of a Mg supplement and continue to try and raise it manually (seems costly)

2) buy a bulk quantity of Mg from somewhere like bulk reef supply (somewhat expensive, plus i'd have to wait for shipping)

3) try to raise my Mg via several large water changes (sounds stressful to livestock)

Time is a factor -- i've got a couple pieces of SPS that are being troopers about my terrible water, but i don't know how much longer they are going to tolerate the instability.

thoughts? thanks!



Last edited by timdanger; 01/29/2010 at 08:50 AM. Reason: precision edit
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Unread 01/29/2010, 09:05 AM   #2
timdanger
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and, as a follow-up... if i were to buy a bulk quantity of straight magnesium chloride, does anyone have a suggested readily-available brand?


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Unread 01/29/2010, 11:57 AM   #3
vegaskid11
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I buy mine from Bulk Reef Supply. You may want to use the Mag Sulfate in addition to the Mag Chloride in the proportions that Randy has laid out so that you can keep a balanced ionic level. I believe when you are trying to raise mg levels drastically this is even more important.

You should mix 3 cups of Mag Sulfate with 5 cups of Mag Chloride in fresh water to make a 1 gallon solution. Let this dissolve for 24 hours and then dose it slowly into your tank. 1 gallon of this solution will contain something like 47,000ppm of magnesium.

If your tank is 45 gallons and your Mg level is a 1000 and you want to be at or around 1350 then you will need about 1250ml of the solution or roughly 1/3of your gallon of stock solution. Split the addition up over 3 day period.

FWIW, you can pick up a 1/2 gallon of dry MgChloride and a 1/2 gallon of MgSulphate from BRS for 11 dollars each plus shipping. This would likely last you for 3 years or more. Good Luck

The information comes from here:
An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php


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Unread 01/29/2010, 12:06 PM   #4
Randy Holmes-Farley
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I do not recommend choice 3. One or 2 are fine.

This has more:

Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html


Do-It-Yourself Magnesium Supplements for the Reef Aquarium
http://reefkeeping.com/issues/2006-07/rhf/index.php


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Unread 01/29/2010, 12:41 PM   #5
timdanger
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Vegaskid, thanks for the advice.

Randy, I read your article (several of them, actually) -- all have been very helpful.

the issue that i'm having is figuring out what might make the most sense in terms of how quickly it would work and how expensive it would be. bulk reef supply Mg might take several days to get here -- and by the time i pay for expedited shipping, it might be as expensive as going to buy larger quantities of the Seachem product (etc.).

unfortunately (or fortunately), my decision might be made for me. it's supposed to snow here tonight, so nobody has any de-icer. does anyone have any other ideas of where else i can get mag sulfate and/or mag chloride?


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Unread 01/29/2010, 01:32 PM   #6
chuckreef
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While not a reccomendation per se. For years I used the Sea Chem magnesium product alone to adjust new systems and maintain mag as it was the only thing available locally. (Come to think of it, I don't think BRS even existed back then (mid 1990s).)

Then I read somehwere that the seachem product really is mostly mag sulfate (not sure where I read that), so about three years ago I decided to just use epsom salts from the local supermarket becasue if that articel was correct, that's what I was always doing anyway. While, in theroy this practice will increas sulfate and decrease chloride concentrations and shift the system away from the normal SW "balance;" I have not seen any detrimental effects from using just the mag sulfate (heptahydrate I think) alone .

So, not to steel your thread, but does anyone know what the symptoms and/or effects of this (rather slight) imbalance in these two major ions would be?

Randy, I've seen your graphs, and agree the shift in concetrations will occur, but do you have any discussion(s) of what the actual efrfects of this shift will be in any of your many excellent documents? Or, any thoughts on this practice (using Mg sulfate alone)?


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Unread 01/29/2010, 01:37 PM   #7
timdanger
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you're not stealing the thread -- this is valuable discussion material (to me anyway!). i'd be curious to know that, too, as i think i'd be able to find epsom salt today. the seachem product is the only one i know of that i can find locally today (may be others, but i'm not sure). i was concerned about using epsom salt because of the buildup of sulfates, but, like you, i'm not sure of what the downside of that is.

i did see in another post where Randy specifically cited Seachem not being ionically balanced as a reason to avoid using it.


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Unread 01/29/2010, 02:19 PM   #8
chuckreef
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Good, I did not want to intrude on your post.

40 gals is not that large, so, by my experience, (and yours too becasue you already dosed SeaChem Mag) you could use epsom salts now (tonight and tomorow night) to get up to 1200 or 1250 (low end of the band) and then raise the rest with a chlodride salt over time.

Then, if anyone comes up with a non-theroretical reason why we should not do this, you could do a few very large water changes with properly (I.e., with Cl and sulfate in proportion) adjusted SW mix later.


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Unread 01/29/2010, 04:21 PM   #9
timdanger
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just read on another recent thread where Randy has said it is not clear what the detrimental effect of elevated sulfates are in aquaria, if any. having said that, he said he recommends magnesium chloride over magnesium sulfate, but better to combine the two in correct ratios per his recipe.

i'm assuming that this recommendation of the magnesium chloride over magnesium sulfate is due to the fact that the excess sulfate builds up more substantially (relatively speaking) when using magnesium sulfate than the excess chloride does when using magnesium chloride.

having said that, it seems like you can reduce the detrimental effects with water changes.

i guess the way i look at it, if i'm going to be ionically imbalanced anyway, i might as well not be paying seachem to make me that way!


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Unread 01/29/2010, 05:29 PM   #10
HighlandReefer
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Effects of high sulfate in a marine enviroment:
Molybdenum Availability, Nitrogen Limitation, and Phytoplankton Growth in Natural Waters
http://www.sciencemag.org/cgi/conten...t/229/4714/653

From this article:

Molybdenum Availability, Nitrogen Limitation, and Phytoplankton Growth in Natural Waters
ROBERT W. HOWARTH 1 and JONATHAN J. COLE 2
1 Section of Ecology and Systematics, Cornell University, Ithaca, New York 14853
2 Institute for Ecosystem Studies, Cary Arboretum, New York Botanical Garden, Millbrook, New York 12545



Sulfate inhibits molybdate assimilation by phytoplankton, making molybdate less available in seawater than it is in freshwater. As a result, nitrogen fixation and nitrate assimilation, both processes that require molybdenum, may require a greater expenditure of energy in seawater than in freshwater. This may explain in part why coastal marine ecosystems are usually nitrogen limited whereas lakes usually are not. Experimentally increasing the ratio of sulfate to molybdate (i) inhibits molybdate uptake, (ii) slows nitrogen fixation rates, and (iii) slows the growth of organisms that use nitrate as their nitrogen source.

Submitted on March 1, 1985
Accepted on June 12, 1985


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Unread 01/29/2010, 11:00 PM   #11
timdanger
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Quote:
Originally Posted by HighlandReefer View Post
Effects of high sulfate in a marine enviroment:
Molybdenum Availability, Nitrogen Limitation, and Phytoplankton Growth in Natural Waters
http://www.sciencemag.org/cgi/conten...t/229/4714/653

From this article:

Molybdenum Availability, Nitrogen Limitation, and Phytoplankton Growth in Natural Waters
ROBERT W. HOWARTH 1 and JONATHAN J. COLE 2
1 Section of Ecology and Systematics, Cornell University, Ithaca, New York 14853
2 Institute for Ecosystem Studies, Cary Arboretum, New York Botanical Garden, Millbrook, New York 12545



Sulfate inhibits molybdate assimilation by phytoplankton, making molybdate less available in seawater than it is in freshwater. As a result, nitrogen fixation and nitrate assimilation, both processes that require molybdenum, may require a greater expenditure of energy in seawater than in freshwater. This may explain in part why coastal marine ecosystems are usually nitrogen limited whereas lakes usually are not. Experimentally increasing the ratio of sulfate to molybdate (i) inhibits molybdate uptake, (ii) slows nitrogen fixation rates, and (iii) slows the growth of organisms that use nitrate as their nitrogen source.

Submitted on March 1, 1985
Accepted on June 12, 1985

i love this forum.

thanks everyone for the advice.


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Unread 01/30/2010, 08:35 AM   #12
Randy Holmes-Farley
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So, not to steel your thread, but does anyone know what the symptoms and/or effects of this (rather slight) imbalance in these two major ions would be?

Randy, I've seen your graphs, and agree the shift in concetrations will occur, but do you have any discussion(s) of what the actual efrfects of this shift will be in any of your many excellent documents? Or, any thoughts on this practice (using Mg sulfate alone)?


There is quite limited info in this area, so it may be OK, but it is a risk of being unnatural and so of causing issues that we cannot foresee.


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