MG thoughts / confusion

[FernBluffReef]

I’ve been having issues with LPS randomly dying or not opening like they should. Torches, hammers, Duncan’s, etc. Been dosing RS Alk, CA and Mg.

Recently switched to RS 4 part and noticed a marked improvement. Did an ICP and found critical low on iodine and Magnese. Added to bring that up and just got a test kit. LPS noticeably happier. Doubled if not tripled torch extension etc. Much happier corals. Bummed I did not realize the RS was a seven part early on - lost things I should not have. Nonetheless things are much better now.

I’m now seeing MG dropping. While I’m maintaining the other parameters. Been adding MG although not a lot as tad taken back its declining. Wondering on thoughts if what I’m seeing makes sense and if I should fully correct the MG to get closer to where most say LPS prefer? (Over 1,400) or leave as is given corals are noticeably improving. Ages ago in a previous reefing life I “believe” I just used 2 part and that was 23 years ago and not the same sorts of corals so relearning some

All tests are Hanna
- S.G. 1.025
- ALK 8.2
- PH 7.8 (working on building a scrubber)
- Nitrate 6.9
- Phosphate .16 (need to bring down a bit)
- CA 432
- MG 1,255 (Hanna tends to read low. RS says 1,320 upon double check). A month ago I had Hanna at 1,345 and two months ago I had Hannah at 1,400 which is about the time I switched to the new 4 part

Again corals have reacted extremely positively to the 4 part and the further addition to address iodine and Manganese. That said, I’ve noticed the 4 part which is based on CA dosing does not maintain ALK like it should and I have to manually dose some extra. When running the single elements I was also dosing more MG then prescribed to get it to the 1,400 where I was. I’m just taken aback that my MG has declined so far.

For the past just under a week I manually dosed an extra 10ml of RS MG which is not a lot - only a couple points on a 525L like mine but over the same time my MG has continued on a slow downward trend. This morning I dosed and extra 20ML of MG and will do so for a while to make sure it increases towards where I want to see it. But I’m confused as I understood MG wasn’t something that got depleted all that fast so wondering if I’m overlooking something as I now have to manually dose extra ALK and MG daily which kinda defeats the purpose of the 4-part

I am using RS blue bucket which is roughly MG 1,320. But I’m only changing 10% every two weeks so while I do expect to have to add some MG to keep to ~1,400 I don’t think that is enough to explain the rate of decrease.

Thoughts? What am I missing

Other info. My tank is 7-8 months old. RS 525 started with dry rock. I can’t keep an SPS alive at all as yet but the LPSs, Anemone and fish are doing great save a bit of ich that is slowly getting better. I’ve grown massive corals 23 years ago just getting back into things so not a complete newbie. Prior tank was larger and all wild live rock so there are new learnings in having to deal with rock and size wise but tank is pretty stable at this point. Coraline everywhere etc

 

[Randy Holmes-Farley]

IMO, all of the magnesium values are fine, and the bouncing around likely reflects test error, not real changes.

Manganese is rapidly depleted and a single dose won’t fix it. It needs to be fused regularly if you want to maintain higher levels.

 

[FernBluffReef]

IMO, all of the magnesium values are fine, and the bouncing around likely reflects test error, not real changes.

Manganese is rapidly depleted and a single dose won’t fix it. It needs to be fused regularly if you want to maintain higher levels.

Thx. Yeah that is some feedback I got when getting the ICP showing critical low - that Manganese and Iodine are rapidly depleted and I’d need to regularly add / some question if really needed. Etc.

I did a one time correction and no more as yet as I’m dosing the 4 part and in theory the included trace supplements there are supposed to maintain. I just got my test kit for those and have not tested as yet but for sure - I saw immediate and significant improvement when starting trace element dosing.

I’m a bit confused on the comment around MG testing error, as the results have not been erratic rather very consistently headed on a downward trend and the decline is now beyond the accuracy range of the tests. I’m aware the MG tests are one of the worst but RS and Hanna here are giving all similar numbers and all consistently declining otherwise Id be with you on testing errors. The results are consistent so I don’t think is an error on my part. Agreed the MG testing is only an indicator and not all that accurate when it comes to precise numbers. So my concern is for the declining MG not the actual quantitative numbers

 

[Randy Holmes-Farley]

1400 to 1255 in two months is fast for magnesium, especially if dosing some. That’s why I said test error. Real decline is about 1/10 th of calcium decline at the max, and often much less. Might you have added 1500 ppm of calcium in that time?

I recommend dosing but not testing:

Just say NO to magnesium testing: RMM is born

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing. I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good...

www.reef2reef.com

 

[FernBluffReef]

Re: Might you have added 1500 ppm of calcium in that time?

LoL. No And part of my point / question

I’ll take a deeper look at your article

 

[FernBluffReef]

Performed the RS trace tests today, first time, those are not for the light at heart and not something I will do regularly. The values there seem to be holding reasonably well with the RS 4 part being used. Iron and Iodine being a bit low which isn't surprising given the ICP reported them critically low, and I didn't want to overdose before having a test kit. Clearly these are something I primarily want to rely on an ICP for and should not need all that often.

Manganese is part of the RS Iron so I expect by fixing that level, I've largely corrected the Manganese and it will be sustained. I'll retest the ICP in a few months to see if the 4-part dosing program is working a-ok for me or not, or sooner if the corals tell me otherwise.

I'm still skeptical on MG testing error. I get what you're saying, and I fully see the MG tests as somewhat unreliable - I even had Hanna replace my original set of MG reagents as the first kit was reading ~200 high while the RS kit was much closer to what I expected, using fresh mixed saltwater as a baseline which I know isn't perfect but the RS kit and the fresh saltwater were spot on. The new Hanna reagents gave results inline with the RS (within range of error) and when I sent in the ICP I performed my own tests on the same water to validate my personal testing processes for all the elements I test. My results on the sample water sent in, MG was 1,370 on the Hanna and the ICP was 1,341 and as mentioned over the past month the levels measured using the same reagents have been declining - testing twice over that period - yesterday being the second time that caused me to ask and to increase my MG supplementing. Over that ~month period there has been qty 2 water changes at 10% and the salt from RS target is 1,320 so that will take it down some and I know I have to add back in due to that but the drop lower than that while using the 4 part is what was bothering me. I get the standard consumption ratios, but also understand every tank is different. If the ratios were perfect I would not have to be adding 50% more ALK daily then the RS 4 part recipe calls form based on CA consumption but I know that is a completely different discussion Eitherway will take your advice and not get too worked up about it.

Thanks again for the insights, very helpful

 

[Randy Holmes-Farley]

The RS test cannot detect iron at levels I recommend. I suspect they only recommend a super high level do their test can detect it. Natural iron levels are far, far below what RS recommends and very few people, even those dosing iron keep it that high.

 

[FernBluffReef]

Yes, I read your other posts on that, after I got the ICP back and am not trying to hit RS targets. Seeing what RS target is vs. what the ICP recommended were so divergent lead me to your prior comments and I agree with your thinking.

The ICP put my Iron at N/D and I only originally added sufficient Iron to bring to a projected level of .4ugl which is causing a color change on the RS test but not sufficient to reach their targets. Today I added the remainder of Iron supplement of what I calculated to bring to what the ICP recommended @ .5ul. I'm not going to try and go for the number RS recommends as to your point it seems far out of line.