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Coral Vue Hydros

Help with raising and stabilizing magnesium please


Butchy21

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So I have had my tank up and running 11 months and have had corals in it for 4 months. I've just started testing routinely for magnesium since I have been adding a ton of coral frags lately. I have found that Magnesium is low and remains low after dosing even though I keep up with routine water changes.

 

My parameters are as follows-

Specific gravity 1.024

Calcium 390

Alkalinity 9.0

Magnesium 990

 

I use Salifert test kits, started dosing with Kent tech Magnesium and SeaChem Fusion 2-part additives for Calcium and Alkalinity. I've mainly done 15-20% water changes weekly (Reef crystals salt).

 

When I started dosing, Magnesium was reading 960-990:

Many fellow reefers have suggested only raising Mg 100ppm daily, so I dosed that amount (~5mL of Kent Tech M) every day for 4 days and did not see any change in Magnesium after testing on day 4. I changed 20% of the water, retested and Mg was still 990.

 

I understand it takes a massive amount of Mg to increase from 990-1350ppm, however it seems unlikely that my tank is using 100ppm magnesium per day.

 

My livestock is as follows: SPS (all small frags approximately 1 inch)- green slimer, montipora, birdsnest, challice, pavona), LPS (almost all very small frags or single head)- hammer, 2-frogspawn, 3-acan, 6 zoos, 3 palys, elegance, 15 head trumpet, kenya tree, tiny xenia.

 

So the concerns I have are- Why do I not see any increase in magnesium if I use an online calculator to adjust Mg by 100ppm X 4 days?

 

 

 

 

 

 

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I suspect your magnesium test kit is giving you false low reading. Not sure why but given you 15 to 20% water change weekly, there is no reason for your Mag to be that low. I would have your water tested by a lfs or with another kit. Magnesium is used by corals but not nearly as fgast as calcium and your calcium is not that low, better if it were in the 420-450 range. Get your mag tested else where, and until then don't worry too much.

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Bad test kit. what salt mix do you use?

I use reef crystals. As for the Mg test kit, it was purchased two weeks ago so I know it is at least not expired.

I suspect your magnesium test kit is giving you false low reading. Not sure why but given you 15 to 20% water change weekly, there is no reason for your Mag to be that low. I would have your water tested by a lfs or with another kit. Magnesium is used by corals but not nearly as fgast as calcium and your calcium is not that low, better if it were in the 420-450 range. Get your mag tested else where, and until then don't worry too much.

Thanks for the tip, I will definitely take a water sample to LFS next trip I take. Would you suggest to stop dosing the Mg and just keep up with normal water changes until then?

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So i ended up getting to LFS- they used Seachem Mg test and got 1200 (even though I was still reading 990), so it was that my Salifert test kit that was bad. Sent it back to Amazon for a replacement, I hope this one works~!

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So new Mg test kit came (Salifert)- tested tank and it was 960 again?! I have not dosed in about 7-10 days because old test kit was junk. Tested new batch of Reef crystals water and it was ~990. I cant imainge my Mg could drop 1200 to 960 in a week. So is it that my salt mix is very low in Mg AND another crap test kit?

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DIt is likely that what you are seeing is differences in the performance of the test. I suspect that because using two different, hopefully different lots, Salifert kits you get essentially the same result.

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So new Mg test kit came (Salifert)- tested tank and it was 960 again?! I have not dosed in about 7-10 days because old test kit was junk. Tested new batch of Reef crystals water and it was ~990. I cant imainge my Mg could drop 1200 to 960 in a week. So is it that my salt mix is very low in Mg AND another crap test kit?

 

Describe in detail how you are reading the Mg number. How do you read the ML remaining in the syringe? Do you continue to swirl the vial to make sure you get a nice grey or blue instead of it turning back to pink? Are you sure you're using the right amount of water from the tank and putting the right amount of drops in?

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Describe in detail how you are reading the Mg number. How do you read the ML remaining in the syringe? Do you continue to swirl the vial to make sure you get a nice grey or blue instead of it turning back to pink? Are you sure you're using the right amount of water from the tank and putting the right amount of drops in?

I'm not at home with the actual test kit- but I think the test was something like this and I followed it very specifically:

 

1. Add with the 2 ml syringe 2 ml of water in the test vial.

2. Add drops of Mg-1 (I cant remember if it was 4 or 5 drops) and swirl gently for 30 seconds.

3. Add 1 spoon of Mg-2 powder and swirl for 10 seconds.

4. Fill syringe until the lower end of the black syringe part is at the 1.00 ml mark.

5. Start adding the Mg-3 reagent with the 1 ml syringe to the testvial until the color changes to gray or blue. Do this drop wise and swirl after each drop for a second or two.

6. Hold the syringe with the tip facing upward and read the position of the upper end of the black syringe part.

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