Reef Calculator for Mg levels

[Weetabix7]

Does anyone know of a good Reef Calculator that shows what the balance level of Mg is for different Ca and Alk levels?

For ex, I want to know what the balanced Mg level is if my Ca level is 440.

I know of this calculator, but it doesn't give that information:

http://home.comcast.net/~jdieck1/chemcalc.html

[brshriver]

I don't think that you are looking at it correctly, although I may be wrong. You don't try to balance Mag with CA and Alk. You need to maintain a proper magnesium level in order to maintain the proper CA and Alk levels. CA and carbonate exist in a supersaturated state in natural sea water. They don't precipitate out because the magnesium in the sea water provides a boding site in solution for the CA and carbonate ions. I don't understand the chemistry behind this "bonding" though, I just know that it exist. If magnesium levels fall too low, it makes it hard to maintain CA and or Alk because the CA and carbonate ions tend to precipitate out of solution as calciumcarbonate. I think coral calcification rates also slow down when the supersaturated states of CA and Alk do not exist. Tanks with low magnesium will require excessive dosing to maintain ca and alk. They will also have more calcium carbonate deposits on heaters and other heat sources than normal.

 

So, it is important to keep magnesium levels at or above natural sea water levels regardless of the CA or carbonate levels. I shoot for 1300 to 1350. Up to 1500 is fine.

 

I have had bad results with most magnesium kits because they tend to measure too high (RedSea and Salifert). Cheaper ones miss read some of the CA as magnesium. I have had good luck with SeaChem and Elos magnesium kits. SeaChem provides a reference solution with their kit to test the test kit against. So my assessments of other test kits assumes that SeaChem's reference solution really is at the magnesium level that it says it is. If you have a cheaper kit, shoot for a level of 1500 in case it reads high.

 

There are a bunch of reef calculators out there for figuring out dosing, but I have never seen one that does what you are asking.

 

Go to RCs chemistry forum. Click on the pinned topic at the top called reef chemistry articles. You will see the links there. I think the calculator you listed is there along with lots of good articles on magnesium - most written by Randy Holmes Farley.

http://archive.reefcentral.com/forums/show...threadid=102605

 

HTH

[Sac_State]

http://www.nano-reef.com/forums/index.php?...6&st=0&

 

 

http://www.reefkeeping.com/issues/2007-03/rhf/index.php

 

http://reefkeeping.com/issues/2007-04/rhf/index.php

 

http://reefkeeping.com/issues/2006-07/rhf/index.php

[brshriver]

If you are looking for a balanced dosing schedule, Randy Holmes Farley's improved 2 part DIY system, now has a mag part and has that information. It is essentially a three part dosing system now

http://reefkeeping.com/issues/2006-02/rhf/index.php

[Weetabix7]

Thanks guys, that helps.

Brshriver, I am using a Seachem test kit for Mg. Haven't checked ref. sample recently, will do later today.

Mg tested at 1125 last night, and approx. 1200 today after I added a supplement last night.

How much can you safely raise Mg in a day? I don't want to shock the tank.

My Ph is reading really low too, so I'm trying to figure out the wisest way to adjust everything without totally freaking the corals out w/too many changes.

[brshriver]

Thanks guys, that helps.

Brshriver, I am using a Seachem test kit for Mg. Haven't checked ref. sample recently, will do later today.

Mg tested at 1125 last night, and approx. 1200 today after I added a supplement last night.

How much can you safely raise Mg in a day? I don't want to shock the tank.

My Ph is reading really low too, so I'm trying to figure out the wisest way to adjust everything without totally freaking the corals out w/too many changes.

I like SeaChem the best, although it is the slowest test due to the step that filters out precipitated calcium.

 

Raise it slowly. I have seen "upper limits" for raising this for a day but I can't remember them. Maybe 100pm? No need to raise it by more than 50 or even 25 though in my opinion. You are better off going slowly and testing all three every day - Ca, Alk and mag.

 

Raising mag should help stabilize alk which should help with ph a little. If you are using a DIY two/three part, make sure you read the parts in the links above about the difference between baking soda and soda ash in regards to pH. Basically, soad ash will raise pH, baking soda may lower it a little (my solution tests out at 7.8 ph on a meter). If you bake baking soda before using it, I believe it turns to soda ash. The NR thread that someone else listed above talks about this.

 

Good luck! My SPS tanks had mag levels of 1000 when I was learning how to keep things stable before I noticed the low mag (I got lazy and quit testing it). I raised it over two or three weeks slowly and all was fine.

[The Propagator]

You may find that after the initial few doses of magnesium that it seems to be dropping a good amount versus what you have introduced the day before. This is typical of a system thats been deprived of mag for a while. It pretty much soaks it up as you put it in.

My 40 did that and it freaked me out LOL!

I was like "WTFMAN !! Where it go ? " every living organism that consumes it seemed to soak it up as soon as I put it in the tank at 1st LOL!

I raised mine at the max per day of 100ppm. Took me 4 days in the 40 ( YUP it was that low ! )

3 days in the 100 and 75.

[Weetabix7]

Thanks for that info Prop, that helps.

My test results last night were:

Mg-- 1200

Ca-- 380

Alk-- 2.0 meq/l

 

I was thinking of holding off on raising Ca til I had Mg and Alk up a bit, what do you think about that?

[The Propagator]

Keep on trucking with them both the same as normal.

[d0ughb0y]

mg should be approx 3x Ca, so if your Ca is 400, then Mg should be 1200 give or take.

[brshriver]

Thanks for that info Prop, that helps.

My test results last night were:

Mg-- 1200

Ca-- 380

Alk-- 2.0 meq/l

 

I was thinking of holding off on raising Ca til I had Mg and Alk up a bit, what do you think about that?

CA is fine. You can run a thriving system at 380 Ca. Some people target 350 to 400 and run Alk higher. I'd try to get my Alk up around 4 and Mg over 1300.

 

No worries though, those numbers aren't going to kill anything, so slowly bring them up over time. Keep an eye on your corals and see what they think of the changes. Their opinion is more important than the test kit's

 

I target 400 for Ca and typcially run from 350 to 400. I targe 4 t 5 meg/l for Alk because I run a Ca reactor and it is always dumping CO2 into my system, so I want Alk higher to compensate. I target 1350 for Mag.

[brshriver]

mg should be approx 3x Ca, so if your Ca is 400, then Mg should be 1200 give or take.

d0ughb0y,

 

What is the logic behind that? That is exactly the question that weetabix initially asked. I have never looked at the absolute levels that way but the balanced dosing programs certainly use those ratios as they line up with how the levels are used by the system.

 

I like to run mag and alk a little higher than natural sea water though. Alk due to the CA reactor. Mag to help keep the others more stable. I am interested in your logic though!

[Weetabix7]

CA is fine. You can run a thriving system at 380 Ca. Some people target 350 to 400 and run Alk higher. I'd try to get my Alk up around 4 and Mg over 1300.

 

No worries though, those numbers aren't going to kill anything, so slowly bring them up over time. Keep an eye on your corals and see what they think of the changes. Their opinion is more important than the test kit's

 

I target 400 for Ca and typcially run from 350 to 400. I targe 4 t 5 meg/l for Alk because I run a Ca reactor and it is always dumping CO2 into my system, so I want Alk higher to compensate. I target 1350 for Mag.

 

Thanks for the input, it really is very helpful.

I agree with you on using the corals as a gauge, it's something I've always done.

Several corals have been looking happier since yest., the only one that isn't is my Duncan.

The thing with the Duncan tho, is that I can't tell what's causing it to be unhappy. It's been unhappy for the last week or so and nothing I do seems to help. It won't open all the way and it keeps sliming a little bit.

Yest it stayed completely closed most of the day and looked more ticked off than usual.

But as I said, everything else either looks happier or as good as it did previously cause it alrdy looked fine.

 

Today's levels are:

Alk- approx 2.5 meq/l

Ca- 380

haven't tested Mg yet.

 

I'm shooting for over 1300 for Mg, 440ish for Ca and 2.5-3.0 meq/l for Alk.

[brshriver]

Sounds like you are on the right path!

 

Let me know if you figure out your duncans. I have two frags in my primarily SPS frag tank. They were in QT before that. In general, they have always been open. But when I moved them to one corner in the frag tank, they never opened. I move them back to the top rack and they open up again. I am not sure why. They get more light and less flow where they are when they are open I think. The QT tank also has less flow. Maybe play with the flow a little? I never entirely figured out the cause with mine. The flow where they were when they did not open was not that high.

[Weetabix7]

According to some information that came with a Tropic Marin Ca/Mg test kit, in order for your Ca and Mg to be in balance with each other your Mg levels should be 3.25 x what your Ca levels are.