Question about Mag

[homer1475]

So my tank has been running now for roughly 3 months, have kept a log the entire time. Current stock is 1 small 2 head green hammer, 1 very small 1 head frogspawn, Hawaiian feather duster, maroon clown, flame angel, 4 smallish frags of zoas( from 5 polyps to 15), and one 4 polyp paly, and various CUC.

Water parameters are:

Temp - 79.5 to 80.6
Salinity - 1.025
PH - 8.0
Ammonia, and nitrites - 0
Nitrate - 8.00
Phosphate - .04
Alk - 9.2
Calc - 380 Little low, but it is 1 day away from my weekly water changes
Mag - 1200

I've only used instant ocean reef crystals, and tested a fresh batch. I got a 1320 @ 1.025, exactly what the bag says it should be. I do weekly 5 gallon water changes religiously, and figured with my light bioload , I could get away with just my water changes for now. I was wrong, could never get MAG levels above 1200(tested with red sea kit which I didn't trust so got a salifert(what everyone here suggested to use) which gave the exact same result. Another lesson learned )

I started dosing fluval sea magnesium.

The recommended does is 5ml per 20 gallons once a week to raise it 5ml/l. I guessed with my LR and sand I have roughly 24G of water. So I dosed 6ml.

First day after the dose I got a slight increase from 1200 to 1280(tested 24 hours later to allow for it to precipitate), Added another 6ml, as this was not nearly enough, 2 days later my mag levels are back to 1200.

I'm lost here on what I should due? Add more, wait, stop adding, I just don't know. Any and all help is appreciated.

 

[dkeller_nc]

A couple of tips; First is to recognize that a magnesium test really doesn't have the precision for 1280 to be a "different" result from 1200. The second is that going from, for example, 1200 to 1300 ppm of magnesium in 30 gallons of water means adding 11.4 grams of magnesium.

But that's pure magnesium; you're adding a magnesium ionic salt (in solution). One salt of magnesium that's typically used in magnesium dosing formulations is magnesium chloride hexahydrate, or MgCl2-6H2O. In this compound, the magnesium content is 12% by weight. So if you need to add 11.4 grams of magnesium, you'd need 95 grams of magnesium chloride hexahydrate.

That's a lot of chemical, and while magnesium supplements typically are a mixture of magnesium chloride and magnesium sulfate, the amount that you must add is still surprisingly high.

 

[bertoni]

I agree that you probably just need to dose more supplement if you want to raise the level. 1200 ppm is fine, in my experience, although I'd raise it to 1275 ppm or so, which is the canonical ocean average. This calculator will help with a dose:

http://reef.diesyst.com/chemcalc/chemcalc.html

I agree that your results seem to show some testing issues, and I'd likely work on that before doing much. On the other hand, a water change might change the magnesium level a fair amount if the source water doesn't match the tank very well.

 

[Gangchenpa]

My Mg is reading around 1600 with Red Sea coral pro salt mix.

 

[homer1475]

Yeah I think I need to work on my testing regime. I tested today and I get 1320. I think my problem arises from not dropping one drop of titrant at a time, or I'm mistaking the color change right away(using the redsea kits).

I'll do a water change on monday and test it again. Thanks for the replies. :thumbsup:

 

[bertoni]

You're welcome! Good luck!

 

[outssider]

watch this video.....

https://www.youtube.com/watch?v=MofaqM-I6uM

 

[DaveRaz]

Although I have all the needed equipment and 2 part to begin dosing, I haven't had to yet. I've been up 6 months and have around 20 corals thus far. Coralline is taking off so I suspect I will have to start any week now. My 20% bi weekly wc has kept up with consumption.

Following along.

 

[homer1475]

watch this video.....

https://www.youtube.com/watch?v=MofaqM-I6uM

Thanks for this vid!

I believe my issue is coming from not going to a deep blue like in the video, I was reading it when it was still slightly purple(giving a low mag reading).

Again thanks for the vid.

 

[outssider]

it will go from dark purple to rich blue in one drop...then you're done