SPS Bleaching

[tcoyle]

temp is stable between 78.8 and 79.3..

From my new learned knowledge the reason to still add magnesium even in the ideal range is this statement : "This third part is necessary to prevent magnesium depletion, and to prevent abnormal chloride and sulfate ratios in the aquarium."

With the last statement the most likely scenario I'm facing.

 

[.AcroKiller.]

I'm pretty sure BRS states this as a guide line and not a definite amount. The amount of magnesium needed is going to vary from tank to tank.

The way I understand it is to test magnesium and try to stay in the general range of about 1280-1350, some go higher , some stay a little lower than that.

If your magnesium is low, dose it. If it is within range why add it? That's the way I've always done it anyway.

No this is not accurate. The magnesium added is to balance the alk and cal. Remember you adding sodium carbonate and calcium chloride.

 

[Jimbo]

I never knew magnesium should be dosed even if levels are within range. Thanks for posting, now if I'd went to the club meeting and listened to your presentation on 2 part dosing I'd have known that!

 

[.AcroKiller.]

Let me clarify this a bit. If water changes are keeping up your magnesium levels then all you have to add is 20 oz of brs magnesium for every gallon of brs 2 part you dose to your tank. If water changes don't keep up then you add what's needed to keep up plus the 20 oz per gallon of 2 part dosed

 

[tcoyle]

Kind of what I figured. So I guess I should just dose 20 oz now and then each gallon used and dose for the past ones that I missed.

 

[.AcroKiller.]

Tim how many gallons of 2 part have you already used

 

[tcoyle]

I think around 3. It's been a bit of challenge as I was dosing more ALK then Calcium for awhile. But I'm pretty sure this is my 3rd gallon of Alk.

 

[.AcroKiller.]

If I was you I would do a couple nice water changes and then start over with the 2 part and magnesium from there

 

[tcoyle]

I'm halfway through another gallon of each now.

 

[tcoyle]

How many gallons on a 65? I do 5 gallons a week.

 

[.AcroKiller.]

Start with at least a 10 gallon water change and then do at least a 10 % a week and just start doing the 2 part with the magnesium dosing from now on. Don't worry about adding all the magnesium from the past 2 part doses

 

[tcoyle]

Sounds good. I added 8 oz tonight and was going to add the rest tomorrow, but guess I'll do the water changes and then start as i am not to far from being done with this round of 2 part.

Thanks for all your help!

 

[roadrashpaul]

Interesting. My mag has been high already and I never dose it. I am going through a gallon of each two part about every 1.5 months. I guess I need to dose some mag as well. I never knew this. I need to do some more reading but this makes sense. Thanks for the info Luis.

 

[cb684]

I do not believe this information is correct. I would recheck with Randy Holmes-Farley
on the chemistry forum before start adding more Mg. To my knowledge the only reason for dosing Magnesium is to replace use or loss due to water change when using salt mixes with low Mg. If your Mg concentration is adequate there is no need to dose it.
With that said, often the magnesium will decrease some per day and in average it would work if you add back what BRS recommend, also a slightly higher than 1400 will likely not cause a problem. Other piece of knowledge is that magnesium tests will become inaccurate fast, so if your test is old, get a new one.

 

[Emac909]

I'd say check all your magnets and pumps in your tank. I just lost a hand full of colonies from a leaking magnet from a pump holder.

 

[fishdoc11]

IME it's not necessary to dose magnesium if your levels stay in a decent range (> 1200). Magnesium is present in such a large amount and decreases in levels so slow that it is only necessary to dose it if it gets low. I have used two part for 15 years to grow SPS without ever dosing magnesium, just water changes to keep it up. I have no doubt that your method works for you Luis and that very well may be the way to go for some people. Just stating my experience.

 

[.AcroKiller.]

Here you go guys this is from Randy's article.

This article provides an improved recipe for the two-part additive using magnesium chloride. This improved recipe does not substantially skew the aquarium's ionic balance. This article also provides the original recipe for folks who cannot find, or choose to not use, magnesium chloride. The buildup of sulfate over time when using the original recipe is shown graphically under different water change scenarios.

http://www.reefkeeping.com/issues/2006-02/rhf/

 

[.AcroKiller.]

Residual Ions from the Calcium and Alkalinity Parts

Adding 1 gallon of each of these additives will result in a residue of ions remaining after calcification. These are mostly sodium and chloride, and the amounts of those two added are equal in numbers (i.e., moles), but slightly different in weight-based concentrations such as ppm because they do not weigh the same.

After adding 594 grams of baking soda (1 gallon of Recipe #1), we will have added 163 grams of sodium. In natural seawater, magnesium is present at about 12.0% of the sodium concentration (by weight). In order to match the magnesium additions to the sodium additions to leave them in a natural ratio, we need to add 12% of 163 grams, or 19.5 grams, of magnesium for every gallon of the two-part additive that we add.

Additionally, we may want to account for magnesium that is actually incorporated into the coral skeletons. For this calculation, I have assumed that the amount of magnesium incorporated is about 6.5% of the calcium level (by weight), or about 2.5% of the skeleton by weight. In the course of adding this gallon of both parts of the two part supplement, we added 141 grams of calcium, so we need to add 0.065 x 141 = 9 grams of magnesium to account for this deposition.

The magnesium parts of the recipe are designed to add enough magnesium so that it is not depleted by either of the two means described above. Because the magnesium supplement (either version) is 47,000 mg/L in magnesium, we need to add (9 +19.5) grams/47 g/L = 610 ml of the magnesium solution for each gallon of the other parts of Recipe #1.

 

[cb684]

These added sodium and chloride ions will with time increase the salinity of the tank. As we add RODI water and do water changes, we adjust the salinity and end up diluting sodium, chloride and magnesium. As time passes, that and consumption will cause magnesium concentration in the water to decrease. When it decreases you add more. That is why IMO it does not make sense to add magnesium if concentration is adequate.
The rate one would need to add magnesium would be about what you said in your post in a tank where there were no other sources of magnesium. But that is not completely true for many tanks because during water changes part of the water with inadequate proportion of sodium, chloride and magnesium is exported, and water with adequate magnesium concentration (sometimes on the upper range) is added correcting its depletion. So if salinity is between 1.025 and 1.026, and magnesium is 1200 - 1400 the proportion between sodium, chloride, and magnesium is correct in spite of the amount of sodium carbonate and calcium chloride added.

 

[.AcroKiller.]

This is a reply from randy to a Reefer here read the last sentence. If what you saying randy would state that in his instructions. Every 2 part instructions I see you have to add the 20oz of magnesium for every gallon of 2 part added.

https://www.reef2reef.com/index.php...arting-BRS-2-part-dosing.224450/#post-2595166