Magnesium issues

[lgerold]

Hi everyone!

I'm having trouble with my magnesium.

Tank description in signature.

Water params are below:
Sal: 1.0265
Calc: 440 ppm
Alk: 10.8 dKH, 3.88 meq/l
Nitrates: 4.4 ppm
Phos: .10 to .25 ppm
Iodine: .03 ppm iodide
PH: 7.98

Magnesium:
1/26: 1080 Dosed with 8 ounces Kent's Tech-M (what I had on hand)
1/27: 1140 Dosed with remaining 8 ounces of Kent's Tech-M

We upgraded this tank using 150 pounds of new branch live rock on 1/7. Some of this branch rock had a minor smell to it, so I expect that the phos and trAtes are due to the breakdown of the remaining debris on the rock.

Used Reef Crystals as water for nearly the entire tank. Only about 20 gallons from the old tank was clean enough to use.

At the same time, we added 100 pounds of live sand, from the Jamaica, not a bag, that's very rich in minerals (white cloud when stirred even a bit.)

Tech-M directions follow:

Important: Shake vigorously immediately prior to use! The preferred method is to test the magnesium level in your aquarium, then add Tech•M at the rate of 1 ml per gallon aquarium capacity per day to bring the level to between 1250 and 1350 ppm. This will raise the level by 18.4 ppm per day. As a routine supplement, if not testing, add two teaspoons (2 capfuls or 10 ml) per 50 gallons tank capacity every week in all marine systems.

So, I need to bring 276 gallons from 1080 ppm to 1350 ppm -
1350-1080 = 270 ppm x 276 gallons = 74,520 ppm magnesium

Tech•M is very concentrated, containing over 70,000 ppm of cationic magnesium

I figured I would need to add the full bottle, to bring us up close to 1350 ppm.


So, after dosing with the entire bottle (16 ounces) on Friday and Saturday, I checked the mag level again this morning. Back to 1080 ppm.

I can think of three possiblities for this:

1. Something is tying up the magnesium
2. The bottle of Tech-M is at fault
3. My test kit is wrong.


Suggestions?

The corals were really stressed after the upgrade. Most are back to their old selves. Xenia is struggling a bit. Yuma's are not happy. Others are happy.

[BoomerD]

You may have to wait for "that OTHER Boomer" to get back to get a good answer to that question...
Kemistery questions leave me with an even more blank look than normal...

[lgerold]

How about "Chemystery?"

[blue_eyes53813]

I went through this with my 265 gallon... make sure you are doing the testing correct.. What brand of test kit do you have? I too had to add ALOT of magnesium to get the tank where it should be.

Do you drip kalk ? All my prim. stablized after the start of dripping kalk at night.

What brand of salt do you use? When I dosed the magnesium for the first time I had to add close to 2 bottles before it was where it needed to be..The corals seemed to use it as fast as I could add it.. I would add 100 ml and test like and hour later... I would waite about 2 hours in between doses and dose and test an hour later... and so on

[lgerold]

I mostly use Salifert tests. Nitrate test is LaMotte (reliable and easier to read at low range.)

I'm pretty confident in the mag test. Before the upgrade, my mag was staying between 1350 and 1450.

Reef Crystals for upgrade salt (2 weeks ago.)

That's an interesting thought that the corals could be using it as fast as I'm adding it.

I'll have to get some more mag supplements.

Do y'all have favorite supplements for mag?

[mps9506]

I haven't had to deal with Mg issues myself in the past. But from what I've read you appear on the right track. RHF recommends targeting you Mg at 1280 or 1250-1350 ppm. I believe you only want to try to raise it by ~100ppm or so a day.
As far as supplements I believe epson salt has been popular with some folks but there are some issues with the sulfates in it, so it might not be a great solution for a one time large boost.
For some reason I thought Reef crystals was typically high in Mg... Have you tested your newely made up Reef Crystals for Mg?
Sorry I'm not more help, but maybe this article will help you out a bit till Boomer responds:
http://www.reefkeeping.com/issues/2006-07/rhf/index.php

It appears it takes a relatively large amount of Mg supplements to raise your Mg levels just a little bit in that size tank.

[Witfull]

http://www.reefs.org/library/article...htbill_wc.html

An initial concentration of 600mg/L was chosen. In natural saltwater, magnesium is found at roughly three times the concentration of calcium. A target level of 1200mg/L has been selected. Using the graph in Figure 5, one can find how many weeks it takes to reach 1200mg/L using water changes, for any tank size. Using 25% or 50% changes, you will see that the graph begins to plateau as the magnesium level nears 1200mg/L. The same occurs as the levels approach 1200mg/L using 10% water changes. Yet with 25 weeks of performing a 10% change per week, the magnesium level is still not up to 1200mg/L. It would take 16 water changes at 10% water volume to reach even 1100mg/L. Using 25% changes, it would take 6 changes to reach 1100mg/L, and about 18 changes to finally reach 1200mg/L. Using 50% water changes - which by most accounts are stressful on reef tank inhabitants - would take 3 changes to clear 1100mg/L, and about 12 changes to reach 1200mg/L. Notice the large number of changes, for all 3 percentages shown here, required just to go from 1100mg/L to 1200mg/L. Notice also that water changes are by no means fast nor inexpensive when used to correct such ionic imbalances.



http://ozreef.org/diy_plans/additives/magnesium.html

But will using this type of additive could cause any long-term effects or problems? Note that the magnesium exists as a sulphate salt in Epsom Salt, in a one to one ratio. If Epsom Salt is added to the water to increase the magnesium levels then there will also be an increase in the sulphate levels. To determine if this will be much of a problem, the various species concentrations in natural water have to be considered:
Magnesium, Mg = 1,300 ppm
Sulphur, S = 900 ppm
Chlorine, Cl = 19,500 ppm

... Now for as how this applies to our reef aquariums, I think that the increase in sulphate concentrations should not cause any problems. Low magnesium levels cause more, and the amount of Epsom Salt required to maintain the magnesium concentrations once they are up to the correct level is small. But having said that, it is better to strive for the conditions that our system inhabitants are adapted to and have evolved in. If a source of magnesium chloride that is not expensive and can be afforded can be found then go ahead and use it. Although because of the ease of access, price and simplicity of use, Epsom Salt is a great place to start, or even end with, maintaining magnesium concentrations.

[lgerold]

Fantastic informtation! Thanks much!

[lgerold]

Hi!

I re-calibrated the refractometer, which was right on. The tank water is 35 ppt.

I double checked the mag level in the tank, and come up with
1020 ppm. Even lower than this morning.

I made up a gallon of water using ro/di, and Reef Crystals. Checked the params for Calcium, Alk, and Magnesium.

Calc: 440 ppm
Alk: 4.2 meq/l
Magnesium: 1140 ppm

Hmmm. Mag is low right out of the tub. RRRRR.

I went to town, LFS surfing, looking for a suitable magnesium supplement, and came up empty handed. So, I purchased some Epsom Salts to use as a supplement.

I will slowly dose the epsom salts over the next few days.

It concerns me that the magnesium was significantly lower this evening than this morning. I makes me think that perhaps something is binding with the magnesium. Is this possible? Has anyone experienced a drop this much in a matter of hours?

[Witfull]

wal-mart, epsom salts 1.97 for 4lbs,,,,wonder how i how this?

[cheeks69]

Originally Posted by lgerold

It concerns me that the magnesium was significantly lower this evening than this morning. I makes me think that perhaps something is binding with the magnesium. Is this possible? Has anyone experienced a drop this much in a matter of hours?

RHF:

Sinks for Magnesium in Marine Aquaria

The primary sink for magnesium in aquaria is coprecipitation with calcium carbonate. This occurs in organisms, as shown in Table 1, and also during the abiotic (non-biologically driven) precipitation of calcium carbonate (such as on heaters).

A potential sink that has been described by some hobbyists is the precipitation of magnesium by limewater (kalkwasser). Both magnesium hydroxide and magnesium carbonate have been suggested. I do not believe that either is an important process in most aquaria. Adding any high pH additive, including limewater, results in the transient formation of magnesium hydroxide. This material quickly redissolves on mixing such that the local pH drops below about 8.6.-9.0. Magnesium carbonate is a more complicated issue, as it is near its solubility limit in seawater and may quickly get coated with a less soluble magnesium calcite. These issues have been dealt with by Bingman20 in much greater detail, and his conclusion is that neither of these precipitates is a likely sink for magnesium.

I would suggest that an alternative way that aquaria using only limewater might become deficient in magnesium over time is that the limewater is simply not delivering magnesium to the aquarium even though it is present in the solid lime. How and why this might happen was discussed above involving the precipitation of magnesium hydroxide in the limewater reservoir. This lack of addition coupled to the ongoing removal of magnesium in calcification could lead to deficiencies in magnesium. Such deficiencies have not become extensive in my aquarium, but it does not have an especially high rate of calcification, and perhaps water changes have eliminated the problem. In any case, those using only limewater (or other systems that do not deliver magnesium) may want to occasionally check magnesium.

Magnesium in Reef Aquaria

[lgerold]

I used to use Kalkwasser before the update 2 weeks ago, but I haven't gotten that far with the new setup. So, since only about 20 gallons of the original water was used, previous kalkwasser usage is probably isn't responsible for the depressed magnesium levels.

Anyone else experience low mag levels in Reef Crystals? Is the product generally consistent from one bucket to another?

[Witfull]

never trust a bucket of salt, but now that you are in the big leagues,,,buckets mean less,,,lol. go to walmart...spend the $2...trust me get to where you need to be,,,then maintain,,or do 25 weeks of water changes+ some time times you need to yank the rope in a tug of war.

[lgerold]

Wit, I trust you so much I already did. Went to Wally World and spent 94 cents each for 6 1 pound boxes. Definitely my least expensive fish supplement purchase!

I've dosed 1 pound already. The calculator shows I'll need to dose a total of 4 pounds.

Mag level hasn't budged. I'll check again in the morning and dose again.

I have seen a positive change in my shriveled pink cynaria (I've had it for only a week, but I'm worried). It's beginning to swell. Could be a coincidence.

[Witfull]

go slow....ben franklin,,,(an early reef tank enthusiast) said..haste makes waste~