Mag drop

[allsps40]

My 50 gallon total system sps tank seems to be using up a large amount of mag lately. I got the mag to 1350 about 3 weeks ago as it was at 1200, figured it was the RC salt I was using before and that the new H2Ocean would maintain the mag around 1300, it has 1380 freshly mixed. I tested it at 1200 last sunday before a water change and it was 1200. After the water change and a small dose it was 1300. Tested it again today and it was 1200. I took a sample to LFS to double check and they got 1050 on Salifert, I use Elos for mag. So info on my tank. 40B with 20L sump about 50g total, ATO with kalk, NW110 skimmer, 27 different sps, some lps, zoas, a leather and 2 clams one about 6 inches across. I do weekly water changes of 5 gallons using D-D H2Ocean salt. ATO with kalk. I dose 1 drop of Lugals daily I do forget sometimes though.
Current water test
Ca 500 a bit higher than normal I increased kalk solution and will be lowering a little
Alk 10 rock stable
ph 7.8-8.2
Mg 1200 Elos 1050 Salifert
Po3 undetectable
No3 10pmm

[disc1]

Do you havea lot of coralline growing? I've heard it pulls a lot of mag when it grows.

[HighlandReefer]

Coral & other mag using reef organisms use Magnesium at a ratio of about 6.5% of the calcium used by weight. Since mag is only 65% as heavy as calcium that would give you a ratio around 4% of the calcium used for the amount of the mag used when comparing ppm. You are not going to use that much calcium in that period of time. You would have to use a lot of calcium (about 2500 ppm) given 100 ppm mag are used. Sounds like testing error or test kit error.

FWIW mag kits are notoriously inaccurate. ;)

[allsps40]

Even Salifert and Elos test kits? YEah I have have an increase in coraline growth.

[HighlandReefer]

One thing when using mag test kits, is that you normally need to add a lot of drops to reach your final end titration. Make sure you thoroughly mix the solution between each drop, especially when you get close to the end point. You can easily over-shoot the end point with larger amounts that need to be mixed. ;)

[allsps40]

Yes I do mix well between drops, I mix it for about 10-15 seconds and wait for a color change. Last nights tests
Alk 9
Ca 460
Mag 1150 after small dose
No3 20
Po4 0
Making salt water to check mag in new salt mix and to do a water change.

[tmz]

The kalk adds no magnesium. Some of the variation could be testing noise but with heavy coraline growth I'd probably bump it up to around 1400ppm in 50ppm per day increments to get a cushion and then tests it in a few weeks.

[allsps40]

Yeah I know kalk only adds alk and ca not mag.

[allsps40]

Tested my freshly mixed for 24 hours H2Ocean salt @1.025 mag is 1200. Tested the tank again 1250. The kit is plus or minus 50 so split the diff and 1200. I think my salt is low in mag. I had this issue when I first got the bucket and contacted DD about it, there is a thread on the DD forum. I was testing low mag in the salt. They check the batch and said it was 1380, told me to mix the bucket which I did already. So I did again and tested again, got 1300. But now I am again having lower mag readings them the stated 1350 on the bucket. I will not be using this salt again. My conclusion is that my tank is using some mag but not much, I am dosing when I see it low, mag is dropping when I do a water change.

[rtparty]

Most Mg kits are off by over 100ppm. Yes, even Salifert and Elos.

H2Ocean is the absolute best salt I have tried in this hobby. That list includes Oceanic, Reef Crystals, ESV and H2Ocean. I may have tried some Red Sea but that was a long time ago and it would have been a small amount. H2Ocean had the most consistent results for me personally.

Every salt I have ever used needed some added Mg. Just part of the game we play. The salt makers use way better testing instruments then we can use and our hobby grade kits can be a joke at times. The more I use and study hobby grade kits, the less I trust them.

With your Mag "jumping around" like it is, I blame the test kit not the salt. Plan that your Mg tests will be off around 100ppm and that is when you do a "good" test. If you cut any corners or have any type of error, that number can grow substantially IMO.

[tmz]

FWIW, I've used Coral Life for over 8yrs . I never have to dose magnesium and get very consistent measures on calcium, alk and mag. Others do well with other salts as well.Opinion will vary but there is no best salt, per se but there are varying price points.

[allsps40]

^ I used to use Coralife salt many years ago, it is ok. So rtparty you are saying tests can be off by 100ppm is the + 100 or -100? Judging that both test kits I used read low I say my mag is low. Now 1200 is ok nothing to worry about IMO. I have used TMPR, IO, RC, Oceanic, Oceanic IO mix, Coralife, HW Reefer, HW Marine Mix and H2Ocean. The old RC formula, HW Reefer and TMPR have been the best salts I have used. H2Ocean is ok I just dont like the low mag and it also has a little brown "dirt" left in the bottom of my mixing bucket after making water.

[bobbychullo]

i really like the H@Ocean. regardless of the "dirt" (it is a natural salt, they extract the salt from the red sea, which i think accounts for the residue). my corals love this salt mix and it was noticeable as soon as I started using it.

it only takes me putting in 5ml of mag into my freshly mixed SW to get it where I want it (1350, sometime the kit says 1320 or so) and the mg tests have been very inconsistent as well (which makes me think test kit error, i consider myself very accurate in my testing procedures). either way, like cliff said, my tank barely uses any Mg compared to my Ca and Alk requirements. coralline, fish, everything is growing so its good for me...

try mixing the salt to 1.026 and see if that makes a difference in the parameters. also, not sure if you are doing this but i've heard to try and mix the whole bucket at once to see if it is an issue with the mixing/settling of the salt during shipping.

[bertoni]

Basically, all of our salt products come from the sea, as far as the NaCl. It's not clear to me that Red Sea is any different from any other product in that regard, although some might use mined salt.

[allsps40]

^ most salt mixes use mined salt H2Ocean and Red Sea are the only 2 the use sea water salt that I know of. I know there is no best salt I just want one that is consistent, mixes clean and has ca alk and mag where I want it. H2Ocean was one of the few that had ca alk and mag with in my range. I am willing to pay for quality salt. Quality control on salt mixes really needs some improvement. If you are going to state a certain level of a trace element you should make sure that it is at least what you advertise. Oh also I am pretty sure my test kit is off. I can test 3 times with the same sample of water and get 3 different results, they will be close to each other off by about 50-100.

[bertoni]

I am not sure that companies would keep track of the source of the salt. They're all pretty interchangeable, in the end.

[allsps40]

No most get their salt from a single supplier for quality control. Though I must say it is lacking in may salt mixes. I have delt with a few salt mix companies in the past and that has given me some (not all) background info on where and how they get some of their ingredients. Tropic Marin, EVS, Tunze for example uses a pharmaceutical grade salt (which is mined only much more pure and refined), IO, RC, Oceanic use mined salt Red Sea and H2Ocean use sea salt. It really does not matter where the salt comes from it is all sodium chloride. Mined salt is sea salt just ancient sea salt left behind by an evaporated sea.

[bertoni]

Maybe. The salt is all from the sea, in the end, whether mined or evaporated. No source is more "natural" than any other, IMO.