low magnesium? is it bad?

[Jritter02]

I tested my water today and everything looked great but magnesium was a little low. Is that a bad thing? I use reef crystals salt. I have a 24g nano and I've had it up since May or so. I have several corals. Few hammers...zoa colonies.. Anyway. Here were my paramaters..
Ammonia 0
Ph 8.1
Nitrate 5-10ppm
Alkalinity 9.6
Mag 1160
Cal 420
Sal 1.024
Temp 78-80


Is the magnesium something I should be worried about? I don't dose The tank with anything besides what's in the reef crystals. Last water change I did was last week and it was 50% over 2 days cause my nitrates were up to 30-40ppm. Input would be appreciated.

 

[pyithar]

my understanding is low magnesium can lead to more calcium carbonate precipitation in the system. i think it should be between 1250-1350ppm. i would raise the magnesium slowly to that range. do frequent testings of calcium and alkalinity since they will get lower if the precipitations are happening.

 

[Jritter02]

What are precipitation? I've been noticing lately what looks like some kind of white build up and white specks on the back of my nano and even on my zoas in the morning before they open up.

 

[toothybugs]

That could be it. The precip I've seen looks a lot like dust that settles out. Calcium carbonate, by itself, is rather bright white - literally it's chalk.

 

[shesacharmer]

Precipitation starts out looking like specks and can get to be fair sized flakes of white that seem to come out of no where. Low mag is one of the first signs that your coral is beginning to use more minerals. Make sure you keep up your water changes and test weekly as it's likely that Alk and Cal will soon be affected as well. Welcome to a new stage in your new tank!

 

[redheadedgirl]

I'm so glad I read this thread. My tank must be in the "new stage" as Shesacharmer put it. I've had my magnesium drop to its lowest, at about 1100 (Salifert kits) and I used a mix of Epsom salts and Magnesium flakes which I drip fed over a day or so. My sun coral had started to go white (which is what got me worried) and stopped feeding. The mix worked great and my magnesium levels are up (around 1230 ish). I have the white specs all over my tank - I had no idea what they were as my tank is only 5 and a half months old. So now I know.

I started testing my calcium when I got my magnesium level up (calcium was already low but magnesium was worse). I have dosed for about a week and the level is up to 410 and my dkh is 9.0. My sun coral is feeding again, albeit not the polyps where the coral has turned white though, which is great news.

My mind is relieved that this may be another stage in my tank!

 

[mandarinfanatic]

There is a good rule of thumb that will keep tank ratios happy. calcium between 390 and 450 based on your choice. magnesium should be 3 times the calcium and to calculate the recommended kh divide calcium in your tank by 43 and it will give you the suggested kh for the specific calcium and magnesium levels in tank. first dose mag to get it to the level you want and then calcium and kh dosed alternately over a few hours or days to get to the levels you want (time period dependent on how far perams are from where you want them to be.

 

[shesacharmer]

You might want to look into kalkwasser (pickling lime) dosing via your ATO. Once you get your levels up to where you want them, with kalkwasser in your ATO the levels for alk and calc should hold steady until the mag runs low. I got my pickling lime at the hardware store (in the canning aisle.)

 

[Jritter02]

I don't have an ATO. I do it manually. So do I need to go get some magnesium from the lfs and start dosing that? Because right now I don't have any

 

[Sk8r]

It's more than the magnesium. If you're not also supplementing calcium and watching your alk as well, you will get no growth from the stony corals like hammer, and ultimately it will impact everything from your fish to your snails. Read Dirt Simple Chemistry, above, and it will explain how to do it. Raise mg first: your alk and cal are ok. I suspect your coral is not feeding or growing yet, since a feeding 3-head hammer can suck up an amazing amount of calcium daily. Mag holds the balance in alk and cal that enables the water to take calcium into solution and feed the corals.

The easiest way to manage this is to use supplements to bring your numbers to what mine are in the sig line, and then put a level tsp of lime [Mrs wages Pickling Lime] per gallon in your topoff water for a young tank; as your coral begins to grow and destabilize your balance, bring that to 2 level teaspoons mixed into the water before you use it.

When doing this, you must lid your lime-laced ro/di topoff water to prevent a skin from forming on it, and loss of some of its goodness.

 

[Jritter02]

^^^^ thanks! I'm at the store now picking up calcium and magnesium. My corals are all doing very well as of now. Zoas are spreading like wildfire. Excited to see what happens when I get all these levels to where they need to be and keeping them there !

 

[Mark9]

I use reef crystals and have never seen mg that low, especially if you just did a 50% wc.
Did you try a re-test?
1160 does not seem right, especially since the other numbers look perfect for reef crystals.

 

[Sk8r]

It could be that that hammer has started feeding. The calcium/alk will hold steady until the mg falls below 1200...and then that level will trend down.
If the calcium falls, snail shells start dissolving and fish don't get the calcium they need for bone and muscle. Think of stony coral as 'calcium vampires'---they force your water constantly to dissolve more calcium to saturate the water, and that mg/alk balance is what adjusts the water ph to be ABLE to dissolve more out of lime and rock and sand. I've seen tanks where the snail shells had turned to paper and it was a wonder the fish were alive, because of that extreme calcium shortage. Had it gone on, everything would have died.

I had about 4 small stonies in a 50 gallon tank, and started supplementing a teaspoon of calcium. They started feeding in earnest, and were sucking down 2 teaspoons of expensive calcium supplement a day---this got crazy-making and expensive. So I went over to limewater, and 5.00 worth of lime does the job for months, as long as I keep that mg up.

 

[Jritter02]

Wow. I must be retarded. I just retested before dosing anything. I use a red sea kit. Its hard to tell on the card if I'm looking for a deep purple or blue as a final color. If I'm looking for the purple then my mag is at 1300. If I'm looking for blue then it's about 1400ppm

 

[Mark9]

Wow. I must be retarded. I just retested before dosing anything. I use a red sea kit. Its hard to tell on the card if I'm looking for a deep purple or blue as a final color. If I'm looking for the purple then my mag is at 1300. If I'm looking for blue then it's about 1400ppm

Watch this video.

 

[Sk8r]

Reading color card results can be quite a challenge. This is why I prefer one that gives a definite color and opacity change, eg, pink suddenly to blue, which gives you a precise number against a chart, based on drops used to accomplish that change. Salifert does such tests.

 

[Jritter02]

That's how this red sea is too. Goes,from pink to purple to blue. That's the one tricky one though. I think I'm good with all my levels.

 

[Sk8r]

Excellent! At least this was a question that led to figuring out how to keep that good range.

 

[Jritter02]

I'm going to keep the calcium and magnesium I bought for dosing in the future if needed. What about the question I had about the white specks I'm starting to see on my zoas? Guy at LFS said it's probably new polyps growing? I have 2 colonies that are growing like theirs no tomorrow. I've got pics but it's kind of hard to see them. I'll try to upload

 

[Sk8r]

If the zoas are healthy, it could just be copepods. But you're not dropping salt in there, are you? a salt burn could made something white-spot. I haven't kept softies in 20 years, so I've not seen this happen. Maybe a question in the softie forum?