[Freddy Twotimes]

I started a chart showing swings of Magnesium and Calcium; I've been testing every day. [Salafert] My magnesium is falling 60ppm per day or more. In a 55 gallon tank I have been adding 5 level spoon-fulls of Tropic Marin Magnesium suppliment when I dose.

Maybe I am reading the instructions wrong but that is what I figure to be about a maximum dose for the amout of water I have. I think I am reading that 6 level spoon-fulls is a maximum dose for 50 gallons of water.

I dosed last night when I saw the Magnesium at 1170 and today I tested twice and it was at 1050 - ? I dont know how it could have dropped after I dose with 5 spoon-fulls? I had a 100ppm increase after dosing two days in a row and one dose of 5 spoon-fulls did nothing at all?

Thats is a huge drop! I tested the Calcium and it is not dropping that fast; the Calcium has gone down 45ppm over a three day period, I dosed the Magnesium bringing it up from 1170 to 1270. I dosed 5 level spoon-fulls two days in a row for that 100ppm increase. The Calcium only dropped 5ppm in the following 24 hours.


Now that I tested today, after adding the 5 spoon-fulls of Magnesium suppliment yesterday, the Calcium went down 20ppm since yesterday.

I dosed again, 5 spoon-fulls and I will see what happens tomorrow. Am I under dosing magnesium? Is Magnesium the primary building block to coraline algae? What would be consuming so much Magnesium?

It seems that the Calcium dropps very slowly if I can keep the Magnesium over 1200ppm. My new goal is 1200ppm - 1300ppm. It is very difficult to hold the Magnesium with it dropping so fast. It is making it hard to understand the doseage amount and frequency. I dont understand how I could get a 100ppm increase with two days of the same doseage and a 150ppm drop after adding a dose.

[weez1959]

I'm pretty much wondering the same thing lately, this whole calcium, magnesium pH alk thing is getting more confusing by the minute...

[wozza]

snap....

[charlie]

I am thinking that the test kits are giving you fits. The Mg should not be dropping like that. I am no chemistry whiz, but that is an awful swing.

Have you tried this link to Mg dosing?
Reef Chemistry Calculator
I don't know what or where else to direct you, maybe we can get Ninong to chip in here with his insight.

[Ninong]

Remember that seawater has three times as much magnesium as calcium: 1300 ppm Mg and 410 ppm Ca. However, I have no idea why your magnesium would be falling so fast. I suspect a problem in your test results.

First off, your 55-gal tank doesn't hold 55 gallons of water. Assuming you have no sump and that you have live rock and possibly a sand bed in your tank, the most you could possibly have would be about 45 gallons of water.

The manufacturer's instructions say that 1 level measuring spoon will raise 30 gallons by 5 ppm. Therefore, 1.5 level measuring spoons should raise your tank by 5 ppm. In order to get a 100 ppm increase, you would have had to add 30 spoonfuls of their product but you say you got a 100 ppm increase after dosing only 10 spoonfuls (5/day for two days). That's why I suspect a problem with your testing.

I suggest you back off on adding so much of this magnesium supplement and stop testing your water every day. You don't have a problem but these daily swings -- assuming you really have them -- are not good. Do things gradually. Stability is a virtue, along with patience.

Try dosing just two spoonfuls a day and wait five or six days before testing again. I see no need to test more than once a week unless you have a problem. I don't think you have a problem right now.

[Ninong]

Just out of curiosity, what brand of salt mix are you using?

[Freddy Twotimes]

Originally Posted by Ninong

Just out of curiosity, what brand of salt mix are you using?

I am using Tropic Marin pro reef. I tested for Magnesium to day twice and got 1320 and 1350. I tested Calcium and got 410. I have a question that would help me determine if my testing is innaccurate...

If you add drops to fast with Salafert test kits can it cause inaccurate readings? Some times I wonder If I am dropping from the syringe a little to fast and it is causing inaccurate readings.

I am not trying to test to much, I am just testing a lot to understand how my tank works. I was thrpwn off guard with the inital readings of low Magbesium and Calcium a week ago. PH is 8.4 and the Alk tested at 2.4-2.7ish.

I guess its fine.

[Ninong]

Originally Posted by Freddy Twotimes

I am using Tropic Marin pro reef.

I was just curious. Sometimes the salt mix is low in magnesium. In this case, it's hard to say because Tropic Marin has tested low in Mg in one test and very high in Mg in another test. In Dr. Craig Bingman's salt study that was published back in March 1999, he tested Mg in Tropic Marin at 1118 ppm (46x24.305). It was one of the lowest in Mg in that test. Then, in this test, Tropic Marin is reported as having 1700 ppm Mg.

I tested for Magnesium to day twice and got 1320 and 1350. I tested Calcium and got 410.

Those numbers are fine.

If you add drops to fast with Salafert test kits can it cause inaccurate readings? Some times I wonder If I am dropping from the syringe a little to fast and it is causing inaccurate readings.

I used LaMotte test kits for calcium and alkalinity and I was very satisfied with them. For magnesium, I used Salifert's test kit. I found that you had to be very, very precise with that test kit. Sometimes, if I didn't like the reading I was getting, I would repeat the test and try to be more careful the second time.

With all test kits, it is important to follow the manufacturer's instructions exactly. It is very important, for instance, that your sample size be as precise as you can get it if you want an accurate reading. In the beginning, I used to check myself by repeating the test (any test) to see if I got the same reading. If the reading was different, it meant I was being careless. Eventually I got to the point where I had confidence in my first test. Usually.

And always take your sample from the same location. I always took my samples from about two inches beneath the surface.

I am not trying to test to much, I am just testing a lot to understand how my tank works. I was thrpwn off guard with the inital readings of low Magbesium and Calcium a week ago. PH is 8.4 and the Alk tested at 2.4-2.7ish.

What I was trying to get across is the idea that you shouldn't worry so much about your parameters unless there is a major problem. Testing every day and trying to make adjustments after each test is probably not as good as waiting several days between tests. What you're trying to avoid is rapid movements up or down.

Your alkalinity is a bit on the low side. It's right inline with NSW alkalinity but most reef hobbyists prefer to keep alkalinity at least 3.0-3.5 mEq/l. And it helps if you report the unit of measurement for alkalinity to avoid confusion. It can be reported in mEq/l, dKH or ppm CaCO3. Obviously if it's reported in ppm CaCO3 there would be no confusing the numbers with either mEq/l or dKH but I have seen some people report high mEq/l numbers and then everyone thought their numbers were fine because we thought they must mean dKH and not mEq/l.