Time to start dosing?

[wlittlefield]

Happy Sunday!

I've had my tank up since August(ish) although most of the livestock and rock were transferred from an older tank.

Since I got up and running, I've had very stable parameters.

dKH: 9.5
Ca: 400 - 430
Ph: 8.2
Na: 1.025
Phosphourus: 18ppb
No3: .5- 3ppm

Up until now, I've been doing weekly water changes but have been learning what is need to reduce that to bi-weekly. That largely accounts for the variation in Ca and NO3.

So, now my question: A few weeks ago, I put in my first SPS and hard corals. I'm starting to see some really great growth on the Birdsnest, Monti, and LPS BUT I'm also seeing a corresponding drop in Ca. At the end of the week I tested it out at 372 and two days after a water change it's 397.

So, I think it is time to start dosing. I'd like to use Kelk in my auto top off but am worried that it will spike my ph and dKH as those elements are really perfect. Should I just give it a try? Should I dose Ca by hand? What Ca product should I dose?

I'm also kicking around the idea of getting an Apex, but am unsure if I really want to pull the trigger. But it would allow me to kill the ATO if the ph spiked from Kelk...

Either way, I'll probably wait till Black Friday to pull the trigger on that so I'll need a dosing solution between now and them. What are your guys suggestions?

I've got a Red Sea magnesium test kit coming in the mail soon as well.
The tank is an IM 30.

 

[Randy Holmes-Farley Verified Community Expert]

I presume alkalinity is dropping too (about 2.8 dKH for each 18-20 ppm of calcium drop).
Magnesium won't have changed much yet.

What is the alk now?

 

[wlittlefield]

I didn't test today but did just before my water change on Friday night. Ca was 372 and dKH was 9.8 so I'm not seeing a corresponding drop...
Along with the magnesium test kit, I've got fresh reagents coming for the Ca test in case they've gone bad. However, it isn't user error since I've gotten the same reading a few times. (plus 2 different users).

WL

 

[Randy Holmes-Farley Verified Community Expert]

What salt mix are you using?

Its certainly Ok to boost the calcium, especially since high calcium generally isn't any problem, but if alkalinity isn't dropping (and you aren't adding any) the low calcium is not from consumption.

 

[wlittlefield]

I'm using Red Sea Coarl Pro Salt.

 

[Randy Holmes-Farley Verified Community Expert]

OK, so coral pro starts with much higher alkalinity than you have, so some alk consumption is taking place.

What alkalinity and calcium level would you like to maintain?

 

[wlittlefield]

I figured that I should shoot for 430ish Ca and an I'm not sure I have a target Dkh. Really, this is the first time I've had to think about controlling elements beyond what a water. Change will take care of.

 

[Randy Holmes-Farley Verified Community Expert]

Calcium target seems not very important. 400-550 ppm seems fine.

Alkalinity has more impact on things like coral growth. I recommend 7-11 dKH, but if it is a ULNS tank, you'll want to be 7-8.5 dKH for SPS corals.

 

[wlittlefield]

So, do you think it would be worth trying the Kelk in a low dose in the ATO reservoir? That might help bring the Ca up to that 400 threshold. I just worry that the Alk might creep up since it's already hovering around 9.3-5

 

[Randy Holmes-Farley Verified Community Expert]

It will boost alkalinity by 2.8 dKH for each 20 ppm of calcium, so you can't make a very big boost to calcium with it, but it is good for maintaining both calcium and alk against consumption. It's all I used on my tank for 20 years.

use calcium chloride for a bump to calcium only.