Kh too high, Ca low

[Brian whitman]

 I started up my red sea max 130 D (34 gallons)  A couple months ago with about 15 pounds of Caribbean live rock and 20 pounds of aragonite live sand.  I have been testing alkalinity using just a cheap Sera test and it usually says eight dkh,  sometimes seven.  This test just counts drops so no way to tell 8.5, etc.  I think I screwed up when I poke the hole in the bottle because the drops come out with a big air bubble.  I’ve been dosing Seachem two part daily using the recommended amount. Today I got a red sea  reef foundation test kit and it showed Dkh at 11.2!  Two tests confirmed.  My calcium is at 380. Magnesium at 1400. Is like to bring the alk down closer to 9 and raise my calcium up closer to 450. I have about 17 frags right now, sps, lps and softies, mostly sps. 

 

Recommendations on getting my alk and calcium to the right levels with Seachem two part?  Dose only calcium for a few days and test?

[OPtasia]

Most liquid cal/alk/mag test kits i've seen use a titration method of adding drops to your samples until they change color, then you compare the number of drops to a chart to get your cal/alk/mag level. I've found them easier to do and interpret than color charts for say ammonia/nitrite/nitrate. 

 

So, you have upgraded your test kits to red sea because you're questioning the readings on your sera kit. I use red sea and I find them to be accurate. Your magnesium is just a little bit high (1350 ideal) and your dkh is at the higher end of the comfort zone at near 12. Neither of these levels are that far out of whack, it just means you have a lot of magnesium in your water (a good thing) and need to add a little more calcium (part one of your two part dosing) to get them in balance. Since you have sensitive corals in your tank, very slowly and gradually dose the calcium into your tank with small (3 ml or less) daily additions until you bring the calcium up gradually. With so much magnesium, you shouldn't see much if any precipitate if you drip your calcium dose in very slowly to a high flow area of the tank.

 

You might also want to check your salinity level. If it's at or above 1.026 then you've probably got some evaporation going on. Remember, when the water evaporates, it leaves all of the salts and elements/minerals behind which can concentrate in your remaining tank water. By slowly dripping some RO/DI water back into the tank, you can lower those concentrations of salts back down to where they need to be.

 

Hope this helps. Here's a video that explains the cal/alk/mag balance better than I can express it.

 

[Clown79]

Your ca is low because the alk is high.

 

As one rises the other one drops.

 

The product you are dosing, is it a 2 part ca and alk dosed in equal quantities?

 

What salt are you using? Have you tested your newly mixed water to see what it's mixing at?

 

If your mag was low, it could be a culprit to the imbalance of ca and alk but high, most have noted no ill effects

[Brian whitman]

I think I’ve had issues with the test. I’m now around 9 dkh but Ca still low. Mg was at 1400. Haven’t tested my mix yet but will do that today. I’m using HW reefer. 

[Brian whitman]

Well I just tested and dkh is 9, Ca is 300 and mg is 720. So that explains it. But it seems every day I test my numbers are all over the place. I tested mg 5 days ago at 1400. Will do a 15% water change tomorrow and test the water first. Then see where I am after. Here’s an FTS so you can see what I have. 

 

 

[Clown79]

When you do your waterchange, test the newly mixed water and then the tank right after the waterchange.

 

That ca is really low at 300.

[Brian whitman]

Yeah I know and can’t figure out why dropping. Although with mg low at 700ish that would explain it. Overall can’t figure out why changing so much mg was 1400 less than a week ago. 

[ReefSafeSolutions]

Any chance that test was just a fluke?  Did you test for Mg a couple of times to verify that number?  If it's consistently testing at 700 and dropped from 1400 in a week, that's pretty wild.  Never heard of anything like that happening. 

 

I always like to test multiple times if I get a number that is out in left field.  Doesn't happen often, but when it does...

[Brian whitman]

I didn’t re test because 1400 was in line with what I was expecting so I could have gotten it wrong. Tank has only been up a couple months so I think that may be the issue. I read something about mg getting used up quickly in a new tank as it binds to rock and crushed coral. I’m going to do 15% water changes  weekly for now and keep testing.