What can influence a tank's Mg reading

Delphinus · #1 04-09-2009, 05:13 AM

I fell off the wagon for Mg testing, when I got back on it recently I found my tanks vary from 900 to 1100. So, been adding Mg to each tank at the same proportions. Two out of three tanks have been showing the same increase per day, as you would expect. However the third is not showing any increase. I've even doubled up the Mg dosing on that tank for a few days now and it remains steady at 900. Were it not for the other two tanks showing increases I would suspect the test kit or the supplement, but we can safely rule those possibilities out.

Is 900 maybe a sort of low water mark for the Elos Mg test kit? Ie., could it be that it's sub-900 but the test kit is unable to show a reading of less than 900?

Trying to think of other possibilities such as perhaps the Mg is simply being absorbed into the biology of the tank but it seems strange to me that the levels are flatlined instead of showing marginal increases or decreases. The resolution per drop on the test kit is 75 so it could be that it is increasing at very small increments and simply hasn't surpassed the threshold to read the next level (975) but again given that the other two tanks are increasing at roughly 75 per day and this tank's proportional additions are now twice that level, it just seems odd to me.

Myka · #2 04-09-2009, 05:19 AM

The resolution per drop is 75 on the Elos? Wow, that sucks. I think it's 5 or 10 on my Salifert. Have you double checked salinity and cal/alk?

Delphinus · #3 04-09-2009, 05:22 AM

That doesn't sound right? You're gonna be adding a LOT of drops to get to 1300-1400 then?? "two hundred and sixty three .. two hundred and sixty .. um .. four? Oh shize I just lost count!!!! One, two, three ...."

I have a Salifert Mg test kit too, now I'm going to go look at the instructions. It's been a while since I used that one because that one is a little fiddlier IIRC..

Myka · #4 04-09-2009, 05:25 AM

Salifert starts at something like 800 or...? I don't have it in front of me, but I'm SO sure that it has very small increments. Very strange that one tank isn't increasing Mg. Cal and Mg both interact with eachother though, so I would check your other parameters. Heck, i'd check all the other params...I do that anytime something seems funny and I usually find something else is off too.

Delphinus · #5 04-09-2009, 05:25 AM

Ah ok just checked, Salifert's resolution is 30 and I forgot you don't count drops but add drops and then compare the 0.01ml's strappings ..

Myka · #6 04-09-2009, 05:29 AM

I edited that one above like 50 times...lol. I'm bad for that. Oh, on second thought...oh and third thought...oh and 46th thought...

Salifert is 30? Huh...thought it was less than that, but still 30 is better than 75.

04scoobysti · #7 04-09-2009, 05:29 AM

Elos is in increments of 50, my MG seems to drop pretty quick to if i don't monitor it and dose.

Delphinus · #8 04-09-2009, 05:29 AM

I guess if I have the Salifert test kit I can use it to see if I have a reading of <900 in that tank. Tomorrow.

Even still though, if it was, it's surprising because it's only a 40g so I do bigger water changes (percentage wise) and I've been using RBS salt which I thought was supposed to be the foshizzlenizzle or something. Seems disappointing to spend a premium on salt and then add Mg like it's going out of style to compensate for a low reading. And just in case anyone asks, I did pour the bag of salt into a bucket and shook it up for 5 minutes before using just in case it's a "you're not mixing your salt enough" type thing...

Delphinus · #9 04-09-2009, 05:33 AM

MY Elos is increments of 75. I hate it because the math isn't straightforward. It's a total afterthought too. The detailed instructions say 100, the inset card has a little sticker over the 100 that says 75. If I use 75 then I get a reading that matches the Salifert. To be honest I'm using the Elos because I want to use it up. I'm not a big fan of Elos with their this's and that's and their oops we really meant this not that but boy oh boy are we ever the best, pardon us for saying. Salifert is a little fussier but a) cheaper and b) a little more consistent from batch to batch??? At least has been in my experience.

Myka · #10 04-09-2009, 05:34 AM

You don't mix your salt for 24 hours? Maybe you aren't mixing good enough...

That's why I never bother with a premium salt. Every once in awhile I get lured in, and buy a bucket or two, but I always end up going back to the IO because I see no difference in my tank, and I don't find dosing to be very expensive. I worked it out that using (expensive) liquid supplements, supplementing an entire bucket of IO costs me less than $16.