Balancing out alkalinity with calcium/mag

[mkunk1]

My tank has been testing at 7dKh , ~500 ppm calcium and 1350 ppm mg.

Ph is typically 7.8-8
temp is ~78.6F
salinity at 32 ppt

Have been thinking about starting kalk, but would it raise calcium and mg too much? Is there anything else you all would recommend instead?

Using reef crystals if that helps.

 

[Randy Holmes-Farley Verified Community Expert]

It adds no magnesium. If you drive alk up you will add 20 ppm calcium for each 2.8 dKH of alkalinity, so I do not think it will immediately boost calcium too much. Very long term, calcium will rise a bit more.

 

[Justin....#JAMAS]

Not trying to steal your thread post or anything but wanted to ask Mr Farley something. I'm using red sea foundation to dose alk when and if it needs it but I noticed my calcium is around 430! Which is fine right now but I can't add calcium with the alk at the same time right? Different days or hours apart? I have reef complete calcium chloride by seachem that has traces of strontium chloride and magnesium chloride. My levels stay consistent but I can't afford a Doser and all the other things I need. I also on have one stylophora, a Duncan , a rose bubble tip, gsp, and about 13 different ZOA's and palys .....
Mag-1350
Alk-10.5 before I dosed this morning to keep at 11
Calcium-430
Nitrate- below 10ppm

 

[Justin....#JAMAS]

As I don't have the money to buy the exact equipment I need for dosing, I only have one sps and one Duncan the others like zoas and palys can be OK with water changes, but I try to keep everything as stable as possible and always stays that way, just curious if I should dose calcium on different days than alk??

 

[Randy Holmes-Farley Verified Community Expert]

Not trying to steal your thread post or anything but wanted to ask Mr Farley something. I'm using red sea foundation to dose alk when and if it needs it but I noticed my calcium is around 430! Which is fine right now but I can't add calcium with the alk at the same time right? Different days or hours apart? I have reef complete calcium chloride by seachem that has traces of strontium chloride and magnesium chloride. My levels stay consistent but I can't afford a Doser and all the other things I need. I also on have one stylophora, a Duncan , a rose bubble tip, gsp, and about 13 different ZOA's and palys .....
Mag-1350
Alk-10.5 before I dosed this morning to keep at 11
Calcium-430
Nitrate- below 10ppm

Hours is fine. Minutes apart may also be fine, as long as the first one mixes in well.

 

[Justin....#JAMAS]

And dosing alkalinity or calcium can bring one another down if magnesium isn't at the right levels correct?

 

[Randy Holmes-Farley Verified Community Expert]

And dosing alkalinity or calcium can bring one another down if magnesium isn't at the right levels correct?

Yes, low magnesium can contribute to increased calcium carbonate precipitation, as can other factors (high alk, high pH, etc.).

 

[Justin....#JAMAS]

Yes, low magnesium can contribute to increased calcium carbonate precipitation, as can other factors (high alk, high pH, etc.).

Ok great! At what parameter does magnesium have to drop under to contribute to this? And for corals to be able to use alk and calcium? I've heard 1350, is that right?
Sorry for the dumb questions, I know and understand a lot of it but some specifics on chemistry I figured I'd ask a chemist lol

 

[Randy Holmes-Farley Verified Community Expert]

Ok great! At what parameter does magnesium have to drop under to contribute to this? And for corals to be able to use alk and calcium? I've heard 1350, is that right?
Sorry for the dumb questions, I know and understand a lot of it but some specifics on chemistry I figured I'd ask a chemist lol

The effect just gets more and more pronounced as magnesium drops, and less and less as it rises. Precipitation is happening in most tanks and there’s no magic number to stop it.

I don’t know that there’s evidence that magnesium is needed for uptake of calcium and alk, but I’m sure that 1250 ppm is adequate because much of the ocean with corals in it have that level of or less.

 

[Justin....#JAMAS]

Ok cool thanks, I was under the impression from videos and listening to people from YouTube to forums, that corals can't utilize the calcium or alk if mag isnt 1350 or over.....Good to know. Thanks

 

[Justin....#JAMAS]

Also, when I go to a online calculator for calcium, it says seachem reef calcium is a polygluconate based supplement for maintaining rather than raising. Just curious, does using this still let the one sps I have utilize calcium? Because my calcium has remained the same for a little while now maybe up or down by 10ppm.

 

[Randy Holmes-Farley Verified Community Expert]

Also, when I go to a online calculator for calcium, it says seachem reef calcium is a polygluconate based supplement for maintaining rather than raising. Just curious, does using this still let the one sps I have utilize calcium? Because my calcium has remained the same for a little while now maybe up or down by 10ppm.

Are you currently using it? (I would not use it, it is a poorly designed and explained product)

It adds an unknown amount of alkalinity along with the calcium. Even after I pointed out to them years ago that this product provides some alkalinity (in an unknown amount since it depends entirely on whether the polygluconate is fully metabolized before being removed from the system), they have neglected to make this clear on the packaging and it leads to problems where people do not understand why alkalinity is rising.

If you used it for a big boost to calcium, you might blow alkalinity through the roof. Hence the concern for "maintaining" calcium and not raising it.

 

[Justin....#JAMAS]

Well I'm glad I asked about it, because I haven't used it but maybe one time! But usually my calcium stays around 450ish with water changes. It's my alkalinity and magnesium that slowly slowly go down. But that's crazy that seachem just ignored you and ignored the fact that this product can cause problems

 

[Randy Holmes-Farley Verified Community Expert]

One beauty of internet forums is threads stay a long time.

This is from 2005:

http://www.reefcentral.com/forums/showthread.php?t=616674

They finally admitted:

"In theory, yes, it could be a single source supplement for balanced Ca/Alk. However, this is likely not the case in practice given the many unknown variables encountered in most systems. "

 

[Justin....#JAMAS]

Wow wow wow! So what do you recommend to use to dose calcium...I'm looking now and on the back of a Kent marine liquid calcium bottle it's calcium chloride is the ingredient...that ok? Or at least better than what I have? Lol