magnesium dropping

bige · Aug 2, 2011

Magnesium was 1300 last week. Now 900. What would cause it to drop so fast? Calcium has been a steady 450.

toyencounters · Aug 2, 2011

Did you do a water change? And did you test the water you use to do a water change?

bige · Aug 2, 2011

I tested it on sunday night. It was 900. Changed 5 g but did not test the new water. Then tested the tank water a couple hours after water change. It was 950.

Macropora · Aug 2, 2011

Did you purchase alot of new corals and added them to the tank last week? How big is your reef tank with the sump?

bige · Aug 3, 2011

I did actually add 10 frags in the past week. It is a biocube 29 with a 15g sump. So around 45 g. The sump will hold 20g but never that full.

caudill187 · Aug 3, 2011

Weird. That is a big drop. I know that Mg++ can precipitate, as with kalk use, but I can't think of a situation where it would precipitate that fast. Water change would do it but it looks like that is not the issue. Did you test more than once? What kind of test kit did you use?

VegasRick · Aug 3, 2011

Is this a new tank? or a bunch of new sand or rock? If either is true Mg can drop quite a bit as it coats calcium carbonate based rock or sand. I have never heard of it dropping this much but I suppose in a small tank you might see it.

Same test kit used in all tests?

shred5 · Aug 3, 2011

I am guessing its your make-up water. 5 gallons is probably more than enough to drop your magnesium that much in a smaller tank. Test your make-up water.
Also did you aerate the water-up water for 24 hrs. ? Makes me think you didnt since it wen up slightly later.

Dave Polzin

subielover · Aug 3, 2011

+1 to the above, also consider that your overall total water volume would be closer to 35 gallons than 45. The Biocube 29's hold a bit more than 20 gallons, just wanted to throw that out there.

bige · Aug 3, 2011

Ok, so... the test kit is an elos. You are correct about water, it did not aerate for 24 hours. I had a friend that owns a maintainence company and he wanted to do a sales pitch. So I made some water about 12 hours before he came He did move stuff around. It was after he left that acans weren't looking right. And tank has been running 3 years but I had a thermometer explode and it wiped tank out. That was 6 months ago. Only started replacing coral about 3 months ago. Thanks for all the quick responses!