High Ca and Mg levels

[LittleRed]

I have a small 30 gallon tank with high levels of Mg and Ca, with a low ALK but I do not dose. I’m assuming my increased levels come from my salt, I use Reef Crystals. Should I switch salts to bring those levels down? I would prefer not to have to start dosing, which is why I’d prefer to continue using a reef salt.

I have never paid a ton of attention to those levels, but my husband used to do the tanks and he had an accident and now can’t maintain them. I’m handling them now, but I would like to be a little more conscientious of better numbers for coral.

The tank is 6 years old with various fish, softies, LPS, and one or two SPS.

The photo has my parameters.

 

[saltyfilmfolks]

Mag is the most common of all test Errors.

I’d re test the calcium.
If you are not dosing , alk and cal fall evenly (despite the higher alk in RC) those numbers don’t make sense. Or rather , shouldn’t be possible.

Wc with RC would actully be good to bring up the alk and wouldn’t effect the cal.

RC should be about 490 in fresh mixed batch. With an alk of 12 or 13

 

[LittleRed]

Mag is the most common of all test Errors.

I’d re test the calcium.
If you are not dosing , alk and cal fall evenly (despite the higher alk in RC) those numbers don’t make sense. Or rather , shouldn’t be possible.

Wc with RC would actully be good to bring up the alk and wouldn’t effect the cal.

RC should be about 490 in fresh mixed batch. With an alk of 12 or 13

I totally wouldn’t put it past me to have messed up the Ca and Mg tests. I’m using Salifert tests, and while I’ve done many a titration professionally, I personally don’t love these tests. I’ll retest and post new numbers if they change.

 

[LittleRed]

Mag is the most common of all test Errors.

I’d re test the calcium.
If you are not dosing , alk and cal fall evenly (despite the higher alk in RC) those numbers don’t make sense. Or rather , shouldn’t be possible.

Wc with RC would actully be good to bring up the alk and wouldn’t effect the cal.

RC should be about 490 in fresh mixed batch. With an alk of 12 or 13

I retested both Ca and Mg twice upon your recommendation. I got 520 ppm for Ca and 1800 ppm for Mg. Both seem ridiculously high and I’m not sure if I am just making a vital mistake on the tests. Any advice?

 

[Martin Kuhn]

The most probable explanations are already there. I have some more that you could consider ....

A)Did you double check your salinity measurement? How ?
Elevated salinity also causes elevated Ca, Alk and Mg
(Alk being low can be just because of high consumption ..)

B) Did You use RODI water ? (Tap water typically adds an uncontrollable amount of elements which is added to the one included in the salt mix

C) Did you mix the dry salt in your bucket before you added some of it to make fresh sea water ? Especially big Buckets can get de-mixed during transport. This results in parts of the mixture getting too high. Others too low Ca Alk mg values

 

[LittleRed]

The most probable explanations are already there. I have some more that you could consider ....

A)Did you double check your salinity measurement? How ?
Elevated salinity also causes elevated Ca, Alk and Mg
(Alk being low can be just because of high consumption ..)

B) Did You use RODI water ? (Tap water typically adds an uncontrollable amount of elements which is added to the one included in the salt mix

C) Did you mix the dry salt in your bucket before you added some of it to make fresh sea water ? Especially big Buckets can get de-mixed during transport. This results in parts of the mixture getting too high. Others too low Ca Alk mg values

I did double check my salinity using a refractometer. I also use RODI water and I did mix the salt before making seawater.

 

[JDtimk]

I would mix up 10 gallons of new saltwater and let it stabilize and then test the alk, cal and mag on that batch of water. If you get similar Cal and Mag numbers to the DT numbers you might have an imbalanced batch of Reef Crystals that is causing the high Cal and Mag. If the numbers are in line with what the manufacturer lists for the salinity you are mixing to, then just do a couple of water changes in your tank with the new batch of saltwater with correct ratios of alk, cal and mag. Then retest your DT and see what your numbers look like.

Additionally you might have calcium carbonate precipitating out onto your heaters or pumps driving down the alk level due to the high Cal levels.
Link to an article that explains the relationship between alk and cal in saltwater.
https://www.advancedaquarist.com/2002/11/chemistry
"Unfortunately, calcium and alkalinity are linked 4,5 in many ways in reef tanks, and these links can lead to serious problems if they are not fully understood. If, for example, you add too much of a calcium supplement, you will drive down alkalinity as you get precipitation of calcium carbonate in the tank. Likewise, adding too much of an alkalinity supplement can result in reduction of calcium. Consequently, trying to correct one problem can cause another. Moreover, if you try to correct a calcium or alkalinity “problem” with the wrong type of additive, you might accomplish nothing more than creating limestone in your tank."

 

[Martin Kuhn]

I’m just trying to help you

A) how did you check correctness of the refrak? Calibration fluid used ?

C) regarded that possible option also ?