Magnesium consumption??

[Shane and John]

So I have a 120 gallon mixed reef.Lps dominated..Mostly Acans and chalices..I have been testing daily for the last 2 months..I have found that my tank consumes almost no calcium or alkalinity.But I am constantly having to dose mag..
My Targets are Mag@1350
Cal @ 450
Alk measured as dkh 8
It seems my tank uses 25pp daily for mag..Tested with elos kits..New

I Guess my question is do other reefers have to dose mag like this?My understanding of reef chemistry is that Corals use more calcium and alk to build their skeletons and grow.

Forgive me if this is mentioned elsewhere,but I have done so much reading on chemistry and Parameters my head gets to spinning....Thanks for your Input..

 

[jrgilles]

Tagging along. I just fought back from low mg (was at about 1150 in my 120 total gallon system.)

It is back up to 1350 now, but I really don't want to have to raise it again, as it took a crazy amount of mg

 

[Shane and John]

Yes..It takes lots of supplimet to raise....Does your tank comsume mag like mine does?
Does your tank comsume calcium and alk?.I guess I am trying to understand why its only mag thats being used in my tank?..I only have a few small sps,but would think lps would still require some Calcuim?

I guess ill mention i am using IO salt and have to dose to get levels correct with each water change..30 gallons every other saturday..

 

[jrgilles]

I'm doing about the same water changes. Mostly I've just been dosing mg. I do have a kalk drip going though controlled by a pH probe, so hard to tell my calcium usage.

Calcium seems to be good though. Have just been dosing mg so far. Now that ca/mg are good, I've moved on to alk. It was at about 7.5, so I'm raising it up. Still trying to get a handle on all the chemisty, so I can't say for sure what my consumption rate is.

Once it is stable, I'll have a better idea what is being used. I'm almost there....

 

[lvsuckerfish]

depending on how many chalice's you have thats were most of the MG is going. chalice thrive off stable and higher side mg. but when you mg changes also should ca and alk not as noticable but should change some if getting way out of wack with mg

 

[Shane and John]

Well I do have a few Large chalices..I dont let my mag get lower thank 1250.But even at that my other parameters dont change.should I maybe try to up my calcium and alk.would that help my mag from going down so fast?

Any input is appreciated!

 

[lvsuckerfish]

when you dose mg how long after until you test?

 

[Shane and John]

I test first..document my findings..Then dose..the next day i will test at the same time.I usually dont dose daily..I Will normally dose about every 3 days or so...I test calcuim and alk weekly now..I was testing everything daily for about 6 weeks..Figured its kinda a waste now..I know what the tank needs..Im ok with dosing only mag.I was just curious if this was normal..

 

[lvsuckerfish]

well I am starting to think so as I been doseing alot of mg lately also I have alot of coraline growing and probly 5 or so chalice but I also top off with kalk daily. thats good you tested until you know the needs thats what I always recommend as you get to know your tank it will be alot better and easier in the long run. but test dose then 24 roughly hrs later is good how is the coraline growth in the tank? it is going crazy or steady?

 

[TotalVapor]

If you have a CA Reactor I would look at NeoMag by Brightwell.

 

[Shane and John]

The Coraline is growing..I try to keep it off the glass but am losing that battle..I dont have a reactor but am thinking of topping off with kalk rather than just straight ro water..maybe that will help..

 

[lvsuckerfish]

thats where your mag is more then likely going then coraline will consume mG also. thats what my issue is I just dump a box of epsom in my tank as that is the eexact amount to bring it up 100ppm for the day I actually have to get some more I ran out.

 

[Shane and John]

Thanks for all of your input...I am going to assume that my chemistry is ok and just know that I have to regularly do up my mag!

 

[Boomer]

It seems my tank uses 25pp daily for mag..Tested with elos kits..New

I Guess my question is do other reefers have to dose mag like this?My understanding of reef chemistry is that Corals use more calcium and alk to build their skeletons and grow.

There is not way any hard corals can consume that much Mg++ or even Coralline. You would have to be loosing the Mg++ abioticly to Hi-Magnesium Calcite (but see below). Corals are made of aragonite and Mg++ does not fit well at all into the Aragonite crystal lattice but fits real nice into the Calcite lattice. Mg++ in hard coral is usually less than on avg 0.5 % or half that of Sr++. Ca++ runs close on avg of 35 %. No animal in the ocean sucks up that much Mg++ unless it is an oyster bed or even if you have mangroves. Or you have some kind of odd testing error.


Try another kit.

Why

I have found that my tank consumes almost no calcium or alkalinity

Can't happen if Mg++ is leaving solution and almost always as MgCO3 or a form of it. So, the Alk has to go down. Like calcium, when your Mg++ drops 20 ppm the Alk drops 2.8 dKH. Mg ++ just can not leave as Mg++. It has to take something with it.

I have never in 40 years heard of your issue and something is very wrong and I suspect the kit.

 

[Shane and John]

Boomer..Thanks so much for your reply..this is why I posted here.I will get another kit today and test.It seemed odd to use that much Mag without the other 2 elements..I will post my findings..Thanks..Shane

 

[Boomer]

OK Shane