Raising Calcium first or Magnesium ?

[Portsmouth Reef]

I am currently trying to raise my Calcium from 300 to around 400 to 450 but cannot get my Magnesium above 880, after being advised that I need to raise my Magnesium before starting to raise my Calcium. As I cant get the Magnesium up I'm wondering whether I should be raising the Calcium first. Can someone give me a definitive answer please ?

[Randy Holmes-Farley]

Well, it would be somewhat better to boost the magnesium first if it is really that low, but that is so low it may be a testing error. Why are calcium and alkalinity so low? Is the salinity really low?

if you raise calcium now, you might get some precipitation of calcium carbonate,but how much, if any, depends on the alkalinity and pH.

Also, note that it takes a huge amount of magnesium additive to boos t magnesium that much.

This calculator shows how much:

Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

[Portsmouth Reef]

Thanks for that. I will carry out another test, and recheck the Calcium and alkalinity.

[Billybeau1]

<a href=showthread.php?s=&postid=8437472#post8437472 target=_blank>Originally posted</a> by Randy Holmes-Farley
Also, not that it takes a huge amount of magnesium additive to boos t magnesium that much.

Should be note that it takes a huge amount. :D

I also suspect with those numbers that your salinity is low.

[Randy Holmes-Farley]

Yes, NOTE :)

[Portsmouth Reef]

Thanks The LFS mentined that it might take the whole jar. Like I say I'll test the Magnesium again. I'm using a Salifert, and the colour graduations aren't that easy to distinguish, as the colour changes from purple to dark grey/blue.I might be adding too much of the crystals in the measure spoon.

[Billybeau1]

The crystals do not have to be exact on the mag kit. If its a tad less or rounded it will not affect the final result. I stop when the pink disappears then take my reading.

BTW - What is your specific gravity and how do you neasure it ?

[fmuakkassa]

Yes it takes a lot of magnesium. I recently discovered my mg to be 1170 and it took about 80 Fl Oz of Kent Marine M.Tek to get to 1280.
One advice. As usual, do it slowly (I did it over a week)

[TekCat]

Maybe water changes would be cheaper solution?

[Randy Holmes-Farley]

Cost-wise, a DIY would be a good way to go:

Do-It-Yourself Magnesium Supplements for the Reef Aquarium
http://reefkeeping.com/issues/2006-07/rhf/index.php

Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

[Portsmouth Reef]

Many thanks for your help and advice

[Randy Holmes-Farley]

You're welcome.

Good luck. :)