IO Calcium boost

[ReefTourist]

My tests are showing Alk ~3.5 meq/L, and calcium at ~300ppm using IO salt in a new tank (90g) with a few nano coral (1 small SPS).
I guess I'm in situation 3 in figure 4 in the alk/calc article here Actually I'm right on that blue line. The calculator linked in the article say's I'll need 144g of dry CaCl2 to boost up to 425.

My newbie questions:

Will dosing that much calc by itself throw off the alk significantly?

Am I correct in my understanding that once I reach appropriate levels I would most likely start dosing a 2-part system? and that with IO I might have to use a little more of the calcium part as water changes would reduce the calcium level but be ok alk-wise?

Thanks for helping a newb out.

 

[Randy Holmes-Farley]

Add calcium chloride to boost the calcium to 420 ppm will have no immediate impact on alkalinity.

IO is not usually that low. What is the salinity?

Yes, once corrected, a two part is a good way to go. You may fix the IO (I add Dowflake to it) or you can just add a bit to the tank when needed.

 

[ReefTourist]

Salinity is at 1.024 - 1.025
I'm using the seachem calcium test which is pretty involved... I could be doing a step incorrectly I guess.

Thanks for the help.

 

[ReefTourist]

At what level does fresh Instant Ocean usually test?

 

[jeffbrig]

Closer to 360ppm in my experience.

 

[IZZY'SREEF]

What is Dowflake? Where do you get it? What is the magnesium level in IO since mag. is a referee between cal and alk. so one does not throw off the other?

 

[Randy Holmes-Farley]

At full NSW salinity (sg = 1.0264), the calcium would be a bit higher (maybe 330 ppm), so perhaps the kit and mix are not far off of normal. I agree that IO is usually roughly 360 ppm. Magnesium is usually normal to a tad low in IO, but not way low.

Dowflake is calcium chloride, some at hardware stores and other places. I describe it in this article:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php

 

[ReefTourist]

Thanks, Randy. I had just bookmarked it before coming back to reply here.
I tested some new saltwater and it was right at 360 ppm. Good call, jeffbrig.
Retested the tank, and it's definitely at 295 ppm (3.5 meq/l alk). The LR has been coloring up nicely so that's where it's all going I guess.

I have a 5g auto-topoff system setup that lasts 4-5 days. I plan on mixing 5 capfuls (5ml each) of Kent's liquid calcium in a full topoff container. Using the calculator mentioned in your article my calcium level will rise a max of 20 ppm per cap. 5 caps - 5 days = 100 ppm dosed at the recommended limit of 20 ppm per day. Sound reasonable?

I think I'll add a magnesium kit right behind a phosphate kit on my list of next test kits to buy.

This has been on of the most helpful threads for me. Thanks everyone.

 

[Randy Holmes-Farley]

Yes, that is a fine plan. This calculator may also be useful in determining the amount to use:

Reef Chemicals Calculator
http://home.comcast.net/~jdieck1/chem_calc3.html