Very low Cal, Very High Mag and some questions

Oldmansanders

New member
Greetings everyone, long time lurker first time poster.

So I recently moved the contents of a 5 year old nano cube 12 G to a Mr. Aqua 25 cube that I have set up sumpless with the following equipment

Tunze 9004 skimmer
AC 50 hob filter runing Phosguard
Eheim Jager 100W
Smart ATO micro
Chinese black box LED from ebay
some Hydor Koriala powerheads

Anyway, I never really tested when I ran the nano cube and kept some easy LPS corals with good success for several years until last summer, when a dino outbreak coupled with what i'm sure were several other negligence based factors crashed the tank and killed pretty much everything but my fish. Afterward I replaced the sand bed and cleaned the crap out of the tank, pretty much starting over with my existing rock. Added a new duncan, some Zoas, a thumbnail size monty frag and a single head of hammer and things were pretty happy for a few months.

Three weeks ago I upgraded to the new tank and moved everything over. Things are running nicely and the diatom bloom from the new sand has mostly sorted itself out.

Anyway, I've never tested my params much in the past, and when I did I used API stuff, which I know is iffy. I handled issues with water changes mostly since the tank was so tiny. This time around, however, I decided to be more scientific about things and dropped the coin on the Red Sea Algae Control (NO3, PO4) and Reef Foundation (Kh, Ca, Mg) test kits. I was pretty surprised by the results I got this afternoon. I've run the tests several times, and carefully read the directions and watched Red Sea's videos and the results are consistent. Here's what I came up with

NO3: 0
PO4: 0.04
Alk: 7.8 dkh
Mg: 1600
Ca: 225 (!!!)

I was really, really surprised that a few frags and rocks with coralline on them would use so much Ca in a few weeks time, but I guess they did. My theory on why the Alk is still within the lower ranges of acceptable is that the Red Sea Coral Pro Salt I used starts at 12dkh, so even though it's been getting consumed with the CA it isn't miserably low yet.

I think the mag is high because my skimmer pulled a ton of water while it was first breaking in, and that was getting replaced with RO, driving my salinity down to around 1.022. To remedy this, I did a 5 gal water change with water I mixed at a 1.028ish to bump it back up. Must have added the extra Mg then? But even then, if I was just getting things back to 1.024, shouldn't the Mg have stayed the same?

Either way, I've got a problem here and I'm trying to figure out how to fix it, preferably without a huge water change. If I dose CA all the way up to 450 or so and bump the Alk to 9, then maintain with two-part, will the MG come down on its own?

I'm going to take a water sample to the LFS for a test to confirm before I do anything, but I'm just looking for a little guidance. Also, if dosing to correct is reasonable, i'm looking for product recommendations. All i have on hand is Seachem Reef Complete, which contains Mg, so I don't wanna mess with that.

Thanks
 
If the tank evaporates much water, you should be able to raise the SG by topping off with saltwater or part saltwater for a while. That method should be easy on the animals.

The corals and coralline would consume alkalinity along with alkalinity at the ratio of 2.8 dKH per 20 ppm of calcium. What's been dosed into the tank? pH buffers are stealth alkalinity supplements and might help explain the calcium reading. Another possibility is problems with the salt batch or settling of the salt in shipment.

The magnesium level is very high, as well. I think getting second opinions on that measurement and the calcium and alkalinity might be a good step.

Have you measure a fresh batch of saltwater recently? If it's not too hard, I might try mixing up the dry salt and then checking the results.
 
aaaaand I'm a big dummy.
So as I was filling syringes, I was doing everything I could to get rid of the air under the plunger. I turned the syringes upside down and tapped them to ditch the air then filled them back up, not realizing that the air accounted for the titrant in the tip. When I just fill the syringes, ignore the air and pay attention to the plunger I get:
Ca: 450
Dkh: 11.5
Mg: 1540

So Mg is still a bit high, but things are not nearly as wonky as they seemed.
Sorry for wasting everybody's time. Maybe someday someone with the same problem will google "Red Sea Syringe" and this thread will come up and it won't have been completely pointless.
 
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