Can't keep alk up. Need advice.

I have a 58g reef. Been running for 2 yrs now. I use kalk in my ato, and reef crystals for my salt. I vodka dose .5 ml a day. Lately I'm having a hard time keeping my alk up. I've tested it with 3 diff kits. It hovers around 6dkh. Cal is 430, mag 1300, sal 1.026. I started dosing 10ml of alk daily and it's not making much of an impact. In the past, the reef crystals kept my alk higher around 11dkh. What is making it drop? Shouldn't the kalk stabilize it? My cal is always stable. Are my corals using that much alk? I have a mix of everything with lots of lps and sps. Any advice would be greatly appreciated.

 

What you're dong sounds good, other than it's not keeping you alk a bit higher,

But,

Nice looking DT!!

 

Beautiful tank. You do have a lot of coral so it can be an issue with alk getting sucked out. Maybe bring your mag up and dose more alk. If I don't dose alk in the morning and night my alk runs low.

 

I hope it's okay to link to another forum for educational purposes.
This is a really long and interesting read about why alk can drop in the absence of a corresponding drop in calcium.
http://www.thereeftank.com/forums/f77/alkalinity-dropping-but-ca-stays-up-213199.html

 

Thanks, I figured mag was fine and within range. How does it only use the alk and not the calcium though?

 

Sometimes excess bacteria can deplete alk.

 

^^^Try this . Bring Mag up to about 1400 then take if from there.

 

The alk is used at a much higher rate than the calcium, and especially the magnesium. What you're seeing is normal. Be sure to dose Ca and alk at equal rates.

 

So if your Ca is 450 and your dkh is 6 you should dose both and not just the alk?

 

^+1. Why dose cal if it's already at the targeted level?