Low Magnesium

[Ken]

I have a newly re-set up 125gal with 40gal sump and fuge, nothing in the fuge yet except 5in of new oolic sand.
160 lb live rock
4 in new oolic sand in tank
5 in. in fuge
very light load
2-60 in actinic white vho
2-60 in. blue vho all 4 fairley new
running about 7hrs a day due to an algae problem
moon light
waiting on skimmer, backordered
very light animal load
ro/di water
instant ocean salt
ph=8.0
temp=76.2
amonia=0
nitrite=0
nitrate=2.5 and droping
dKH=9.0
alkalinity=3.20
calcium=500
salt=1.024
phosphate=0
magnesium=1080

I 've been trying to raise the magnesium with 150ml of Reef Pure balanced magnesium each day for the last 5 days it has come up to 1140 and is now back to 1080, where it started. No water changes in the last 2 weeks. Plan to do 30gal change on Fri.. Can some one tell me what might be going on, How to fix it or is it not a problem?

[SueT]

Thats surprising to me that your calcium can be 500 and mag. that low. They say that magnesium should be 3 times as high as calcium levels. For example my calcium runs ~410ppm and my mag, is 1230. This being a new system it may still need to get settled in. I also use IO salt and love it. My alk. runs about the same as yours in the 9dKh range. I use Tech M by Kent for my mag. I would just try to work on getting the calcium down to 420ppm and see what the mag does with trying to raise it.

[Ken]

Thanks, I guess the only way to lower the calcium is with water changes? It was low at one time and I over shot it with Kent's, just the part A I think. I just got the Tech M today, haven't even un packed it yet. Is that level of mag dangerous to anything? Should I just do the water change on Fri. and wait and see or what?
Ken

[SueT]

I have noticed that Tech M seems to be really easy to raise the levels. I might try it at the dose they suggest, 1 capful per 20g. And then do your water change and give it time to settle and then do a test.

[sasquatch]

Better answers than this will surely follow, I suspect your new sand is throwing it off,it must be elevating the calc just from being finely ground coral, have you checked what your salt mix is giving you?? IO always seems low to me, but it is based on fowlr needs if I remember correctly.Steve

[SueT]

Io-low mag., good alk and calcium.

[Ken]

I haven't checked the change out water yet. It's mixed and the salt is 1.025 but I haven't had time to check anything else yet. Working for a living sure gets in the way of the fun stuff. So you think I should try to raise the mag in the tank before I do the water change?

[SueT]

I would, but it also depends on what your keeping so far. If you don't have any corals yet then you might wait til after the water change. I am sure it'll settle out for you, but it just takes getting a handle on. My 120g was in a mag. mess awhile back and it took me forever to get it right again. It was my own problem of not checking it and dosing like there was no tomorrow. I finally got it right.

[Boomer]

It may be a combo of many things and some revolving around new sand as sasquatch suggested. It is hard to say.

I would start over with this

1. A good water change first and raise the SG to 1.025-1.026

2.Re-check Calcium and Magnesium again and if low raise the Mg up to 1300 ppm by adding Reef Pure 100 pm / day. Add noting else no buffers or Ca++. Recheck Ca++ , Alk and pH to see if they are in line.

Use this to help you

http://home.comcast.net/~jdieck1/chem_calc3.html

[bluespotjawfish]

Boy your tank sounds so much like mine! I have had levels of calcium around 500 ppm for years (something in the tank just raises it, regards of my water changes it always elevates instead of declines). Actually, it has often been in the 600 range if I don't stay on top of the WC to lower it. I have had high alkalinity as well (from tap water).

Recently I tested the magnesium and it was down to 90 (that is not a typo -not 900, but 90). I used Tech M one time (split into two different doses just to make sure I didn't overdose) to raise it to 1300 and it has stayed between 1200 and 1280 on its own without any additional additives other than what is added with WCs. My calcium has dropped to around 420 and is pretty stable now. I even have had to add a bit of buffer to keep it high enough to stay in balance with my alk while that continues to come down to where it should be now that I have a RO/DI unit.

Of course Boomer is the expert and I'd follow his advice over mine. I'm just presenting my own experience to keep you company and to wish you luck!

[My2heartboys]

Originally Posted by SueT

I have noticed that Tech M seems to be really easy to raise the levels. I might try it at the dose they suggest, 1 capful per 20g. And then do your water change and give it time to settle and then do a test.

In the beginning I found Tech M impossible to use to raise magnesium. I started using Tropic Marin's magnesium and it came up quite nicely. This product is also in granular form so it packs a little more into each package than a liquid.

Anne

[SueT]

Originally Posted by My2heartboys

In the beginning I found Tech M impossible to use to raise magnesium. I started using Tropic Marin's magnesium and it came up quite nicely. This product is also in granular form so it packs a little more into each package than a liquid.

Anne

Actually Tech M is the only magnesium product that I have ever used and it's worked great for me. I can't even use the dose Kent recommends to keep the tank stable. I like the liquid form over granular as it's easier on me to use and not have to mix.

[bluespotjawfish]

I agree. When I added mine, I added some, then tested, and then decided how much more to add based on how much it raised with the first dose, then tested again, then I was done. Tech M worked great.

[lcstorc]

Epson Salts. A nice cheap easy way to raise magnesium and it is even listed in the reef chemistry calculator so you know how much to add to get how much difference.

[Ken]

I did a 30gal water change today. Levels in the tank before the change were
pH=8.0
salt=1.025
temp=76.2
calcium-410
magnesium=1185
dKH=12.0
alkalinity=4.20
amonia=0
nitrite=0
nitrate=2.5
phosphate=0

Change water was with RO/Di water and instant ocean salt
pH=7.9
salt=1.026
temp=76.0
dKH=10.8
alkalinity=3.88
calcium=380
magnesium=1050
amonia, nitrite, nitrate and phosphate were all 0
Is it normal for the ca++ and the mag to be that low with instant ocean, and for the dKH and alk to be that high even with RO/DI water. By the way the ro water checks out fine? Am I missing something?
Thanks,
Ken