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View Full Version : Mag Sulfate vice Mag Chloride


MarlinHooker
03/21/2013, 07:00 AM
Anyone out there who uses Mag Sulfate for Mg dosing have any actual observed data on whether using lab grade Eposon salts as your Mg source has any negative effects vice using Mag Chloride?

I've read everything I can about the topic including Randy's article where he says that if you are doing 30-40% PWC/month there is probably no issue. I've talked with the Vice President of Tropic Marin for US Ops who talked to his lead scientist group and they also could not provide any specific negative effects other than it will have an effect of the ionic balance ...

So if you've got some hard facts let's hear them, not too interested in unsupported opinions ... got plenty of those already ... thx

disc1
03/21/2013, 08:05 AM
There's no doubt about it affecting ionic balance, but I haven't anything on how that affects anything.

MarlinHooker
03/21/2013, 09:23 AM
that's my problem ... everyone's quick to say that it effects ionic balance but the "so what?" is always missing ...

disc1
03/21/2013, 09:47 AM
that's my problem ... everyone's quick to say that it effects ionic balance but the "so what?" is always missing ...

See to me it's not about "prove it". I know that keeping my water like real seawater is going to work. Surely corals like it like real seawater. Otherwise why do they live in the sea, right???

Anything else is conjecture either way. It may be fine, or it may not be. I'm not going to risk my livestock to find out when keeping NSW levels is so easy. Why should I even care what would happen at elevated sulfate levels? What purpose would it serve?

bertoni
03/21/2013, 10:20 AM
For me, magnesium chloride is easy enough to get and cheap enough that I don't bother with plain magnesium sulfate, but some people are successful with it. I agree with David and don't see any reason to add another variable to my system.

MarlinHooker
03/21/2013, 01:54 PM
hmmm ... maybe I'm missing something but MgSulfate is way cheaper than the same amount of MgCl ...? You all ahve a source of cheap MgCl on par with lab grade Epson salt?

jerpa
03/21/2013, 02:08 PM
It isn't cheaper than epsom salts but it isn't expensive enough to warrant the risk. That is my opinion anyway. I think I spend ~$10 a year on magnesium supplement and cutting it to $2 a year isn't worth it to me.

MarlinHooker
03/21/2013, 02:31 PM
I wish that were true ... I need to dose 80ml/day to keep my Mg levels at about 1350 and I spend a heck of a lot more than $10 a year on Mg supplement ...

disc1
03/21/2013, 02:34 PM
Where is all your mag going? What salt are you using?

MarlinHooker
03/21/2013, 05:15 PM
Red Sea Coral Pro

I have no idea but if I don't dose Alk, Ca and Mg every day the levels drop like a rock. For the first month or so after cycling I couldn't figure out why I was having trouble with supposedly easy corals ... Once I started to test every day the reason was obvious ... Now that I dose every day (2 tablespoon of baking soda, 120ml Ca and 80ml Mg everything is doing well and the tank is stable everyone is happy and growing ...

jerpa
03/21/2013, 09:10 PM
Wow. I bought a gallon of magnesium chloride and sulfate a year and a half ago and have used less than half. That's a lot of magnesium. I dose a few times a year. Lol.

bnumair
03/21/2013, 09:42 PM
i use RSCpro. most of the time it keeps mag at 1300-1400 range but there are bad batches that bring it down to low 1200. i have a 5gal mag chloride bucket i got from BRS and if i hit those bad batch of salt mix i add 1/4 cup to my ato that keeps it up t 1400.
the other difference i noticed other than already mentioned between mag chloride and sulfate is the amount needed.
mag chloride is needed in less quantity than sulfide for same increase.

tmz
03/22/2013, 01:30 AM
Why would anyone want extra sufalte beyond nsw values? There is plenty already. What good would it possibly do? The ionic imbalance in chloride and sufate from dosing magnesium sulfate is a fact, not an opinion.At some level it might make it easier for sulfate reducing bacteria to flourish in anoxic areas or a drop in chloride ratios might have some effect on NO2 toxcicity. Those are speculative opinions. I can't think of even one possible benefit to speculate about.

I don't know why you have to dose that much magnesium? I almost never dose it and levels hang around 1400ppm in a system packed with stony corals and decent coraline growth.

downbeach
03/22/2013, 06:51 AM
What kits are you using to measure your Ca, Alk and Mg with? The uptake of Mg, by stoney corals, coraline algae, etc., in any reef system is almost negligible. Considering the amount that's in reserve in your system, I don't know what would be using it. Through the years I've been in this hobby, with regular WC's, I've never had to dose Mg.

MarlinHooker
03/22/2013, 08:52 AM
Salifert for Mg, Hanna Checker for Alk & API for Ca. When my LFS checked my numbers they came in around the same using different kits ....

I have no idea why I need to add so much Mg to keep the levels up

As for Mg Sulfate, there is no disagreement that it changes the ionic balance of the seawater, however I can find exactly zero hard data that suggests this is 'bad' in some way ... even the chief scientist for Tropic Marin could not point to anything bad that is known to happen ...

when my phosphates and/or nitrates go up, bad thing happen that manifest themselves in the tank; when my Ca level drops bad things happen in my tank ... when the sulfate level rises what happens? Here I only get opinions with no hard data.

Now if I could get to a point where I didn't need much Mg supplement would I switch to MgCl so that the ionic balance of the water was not different? Sure, but currently that is not the case.

I'll love to figure out what is going on since it appears my experience is somewhat out of the norm even though my critters are doing well ......

tmz
03/22/2013, 11:02 AM
You may cetainly dose what you like to your tank. I personally, wouldn't dose heavy quantities of extra sulfate but would balance it with chloride .There are a number of studies on the effect of sulfides ,produced by sulfate reducing bacteria;just google; sulfate and corals. Here is one example:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3105726/

Here is another reagarding sulfate's eeffects on adsorbtion by corals:

http://www.ncbi.nlm.nih.gov/pubmed/12069344

Here is one on anaerobic sulfate reduction:

http://www.ncbi.nlm.nih.gov/pubmed/16119857

As for cost 3785.41 mls of premixed magnesium sulfate and magnesium chloride costs $10.99 at Bulk Reef Supply Even at 80ml per day that's enough for 47 days or 23 cents per day. Buying mag chloride and mag sulfate in generic forms should reduce even that cost substantially. What do you currently pay for mag sulfate?

tmz
03/22/2013, 11:19 AM
BTW , the same vendor noted above sells dry magnsium sulfate for $18.99 per gllon and dry magnesium chloride for $18.99. Same price .

disc1
03/22/2013, 11:26 AM
Salifert for Mg, Hanna Checker for Alk & API for Ca. When my LFS checked my numbers they came in around the same using different kits ....

I have no idea why I need to add so much Mg to keep the levels up

As for Mg Sulfate, there is no disagreement that it changes the ionic balance of the seawater, however I can find exactly zero hard data that suggests this is 'bad' in some way ... even the chief scientist for Tropic Marin could not point to anything bad that is known to happen ...

when my phosphates and/or nitrates go up, bad thing happen that manifest themselves in the tank; when my Ca level drops bad things happen in my tank ... when the sulfate level rises what happens? Here I only get opinions with no hard data.

Now if I could get to a point where I didn't need much Mg supplement would I switch to MgCl so that the ionic balance of the water was not different? Sure, but currently that is not the case.

I'll love to figure out what is going on since it appears my experience is somewhat out of the norm even though my critters are doing well ......

Sure we haven't found anything that says it is bad. But taking from that the assumption that there isn't anything bad would be flawed logic. We can't find any data that says it isn't bad either. It is a big unknown. If you are comfortable with that unknown, then go for it. As for me, I am not comfortable with the unknown factor there. So I won't. There's nothing to say either one of us is right or wrong there. Maybe you can go with the nothing but mag sulfate approach and let us know what happens. You can be the experiment that starts to build data one way or the other.

biodegraded
03/22/2013, 12:06 PM
To my experience, the amount of dosing is way, way excessive. Throwing in that much Mg is dealing with a symptom. Find and correct the cause and the source of Mg would be more or less moot because of how little would be needed, if any at all outside of water changes.

MarlinHooker
03/22/2013, 12:46 PM
I get a 6lb bag of MgSulfate from the local CVS for $6.25.

I'll go read these references to see what they have to say, thx.

While I agree that just because we haven't found anything bad from this doesn't mean there isn't anything bad, the reverse is also just as likely at this point since we have no evidence either way ... I'm comfortable with this 'unknown' because there is no real evidence that this approach is any more risky than not. Maybe this is because in my professional life my job is about taking calculated risks every day -- it's what I do ...

I also have no real desire to be an experiment about anything, I just want I nice, thriving reef tank to enjoy. And it was purely a money decision since I had no other basis to use. I will reevaluate the sources you provided and recheck my dollar figures, last time they weren't even close but maybe I missed something.

Of course the real question is why do I seem to use so much more Mg than others ...?

reefgeezer
03/22/2013, 12:47 PM
Could you have a precipitation issue that is using mag? Any heavy build-up on heaters or pump housings? Are there any hard deposits (not coralline) on the glass?

MarlinHooker
03/22/2013, 12:58 PM
hmmm ... at first was going to say none, however I do get some small disk-shaped 'deposits' that appear on the back of the aquarium from time to time. They appear to be coralline accept for their color which is a light tan, light greenish color. Really don't know how to tell if this is some type of algae or precipitation? I simple scrap them off when they appear.

MarlinHooker
03/22/2013, 01:07 PM
Ok, so any suggestions on what would cause cronic low Mg levels?

I do a 10% PWC every week
I use Red Coral Sea Pro salt

Ron Reefman
03/23/2013, 04:43 AM
I see you have a 150g DT, how big is the whole system? And what kind of animals do you have? How old is your tank?

I have a 180g DT that is 70% full with sps and lps (the rest are softies) and I dose 300ml of BRS formula cal and alk everyday, but I'm lucky if I dose 300ml of mag every 3-4 weeks. My tank is 3+ years old and has gone from very small corals to really big colonies. Over that same time my dosing levels have gone up and up. What is the history of your tank?

downbeach
03/23/2013, 06:29 AM
Have you tried another test kit? Like Ron, I have a 180 but must have a smaller load, since my dosing is at 8 oz. (236mL) per day, but I use no Mg.
You might read here, and see if anything applies:

http://www.advancedaquarist.com/2003/10/chemistry#section-6

bertoni
03/24/2013, 07:16 PM
The only ways to reduce magnesium are water changes with a lower-magnesium salt, or wait for it to be depleted slowly by calcification, which consumes 15-20 ppm or so of magnesium per 2.8 dKH. I'm not sure what's going on with your systems, but I would do a long-term chart of the magnesium level, and record water changes along with the ppm of magnesium in the new water. Measuring magnesium once per week should be good enough.

disc1
03/24/2013, 08:21 PM
calcification, which consumes 15-20 ppm or so of magnesium per 2.8 dKH.

I think that's the calcium figure Jon. Magnesium consumption should be way lower than that, no?

bnumair
03/24/2013, 09:12 PM
yes to my knowledge 20ppm cal per 2.8dkh alk consumption balances out mag should be much less than that.

tmz
03/24/2013, 09:45 PM
I get a 6lb bag of MgSulfate from the local CVS for $6.25.

Well you could keep doing that instead of buying the hobby mag sulfate at 18.99 per gallon which is 6lbs btw. then mixing it with mag chloride even at 18.99 for 6lbs wouldn't amount to a gret cost increase. Alternatively you could gt mag flake by in larger quantities ;a 50 lb bag can be had for 17.99 if you shop for it.
So, cost is a non issue;extra sulfate is likely to be so at some level of accumulation.

The primary sink for magnesium in aquariums is calcium carbonate fromation by calcreous organisms or abiotic precipitation of calcium carbonate. Skeltal concentrations of magnesium relative to calcium and carbonate are quite small, ranging from 0.5% to around 2.5% of the total skeltal weight in calcifying marine organisms . So, with 50ppm carbonate/1dkh and 20ppm caclium the magnesium used per dkh would be in the single digits( ie less than 1ppm to 3 ppm or so with some adjustments for a prcise weight based measure) . Magnesium also comes in with foods. So, unless ,there is some significant precipitation or the salt mix is inordinately low in magnesium and large water changes are performed frequently, consumption should not be very high requiring only infrequent dosing to maintain recommended levels, ie 1250 to 1350ppm.

I'd personally triple check my testing.

This article maybe of interest:

http://www.advancedaquarist.com/2003/10/chemistry#section-6

it may be teh same one noted above.

MarlinHooker
03/25/2013, 06:08 AM
the system is about 200g with the sump & fuge. It has been up and running since Jul. I have a few SPS but they are smaller frags although my monti caps & others are definitely growing, I have 9 small fish and a lot of LPS with some zoas, mushrooms & leather toadstool which has split 4 times. I have a very large open brain (5-6"), a pretty good sized hammer & a medium sized plate. I added a Maxima a week ago but he doesn't account for the readings. I've been dosing 120ml of Ca & 2 Tblspns of baking soda daily in addition to the Mg

MarlinHooker
03/25/2013, 07:42 AM
ok, found a source of magflake at 1.50/lb + free shipping so Randy's recipe of 5/3 should be good & I'll be switching to this as soon as it arrives. BRS is not an option for MgCl since the shipping at $26 is more than the 1 gal of product at $18.99. My LFS is $3.50/lb + sales tax ...
I'm a lot happier now. I will test my current batch of seawater which is for my weekly PWC tonight but when I checked in the past it was 1300. The problem was it started dropping immediatly. However, what I don't know is the rate it dropped/day & what it was on the day of my next PWC.

Maybe I'm trying too hard to keep it up at around 1350 and it's ok to let it fall to around 1250 or so by the time my next PWC is due?

bertoni
03/25/2013, 08:54 AM
1250 ppm should be fine. I've run a lot lower without any problems.

MarlinHooker
03/25/2013, 11:00 AM
ok, I'll see how much it changes after each PWC