Why is my Mg always so low?

[Jason McK]

Are you sure when you first mix the SW for a water change it's at 1400? What salt are you using

[c_scherer123]

I will check DKH and salt names when I get home.
Last time I checked, the DKH was fairly high (unusually so), but so it is also high in my fresh salt mix.

[Delphinus]

Dumb question but I'll ask it anyhow .. when you're dosing Mg, are you dosing it to bring it back to 1400 or are you dosing the amounts suggested on the bottle? Oh wait, IS there a bottle? What are you dosing for Mg?

Here's my take. Mg is an underappreciated element by the powers that be within the hobby. Commercially available Mg to dose is like taking a peashooter to a shootout where the other gunslingers are carrying Uzi's (Ok my metaphor sucks, but I'm too lazy to think of something else. I use the "it's like draining a lake with an eyedropper" metaphor far too often and it's time to shake things up a bit). I would buy a $30 bottle of Mg solution from the LFS and then end up dumping the entire bottle into my water change water to make it 1400. So now I just buy 20-30 lbs. of MgCl crystals from LittleSilverMax because it's a far more cost effective solution, costs me maybe $80 or whatever but I end up with enough to fill a 5g salt bucket which lasts 6 to 12 months. I end up adding 225ml of it (almost a full cup) to my makeup water to make 1400 and when I dose my tanks I found it surprising how much of it I would need to raise Mg by 100. I forget how much exactly (I write stuff like that down so that I don't need to remember it, consequently, I don't remember what it is when I'm writing a post like this. Sorry. )

So if you're using a commercially available product to dose Mg and just following the instructions of "one capful per X gallons", my bet is that this is just not enough to maintain Mg. It wasn't for me anyhow and I'd be surprised if that truly works for anyone.

Over time Mg will deplete just like Ca and Alk will. Think I've heard the addage that the depletion rate is roughly the same per week as it is for Ca or Alk per day.

[c_scherer123]

Originally Posted by Delphinus

Dumb question but I'll ask it anyhow .. when you're dosing Mg, are you dosing it to bring it back to 1400 or are you dosing the amounts suggested on the bottle? Oh wait, IS there a bottle? What are you dosing for Mg?

Here's my take. Mg is an underappreciated element by the powers that be within the hobby. Commercially available Mg to dose is like taking a peashooter to a shootout where the other gunslingers are carrying Uzi's (Ok my metaphor sucks, but I'm too lazy to think of something else. I use the "it's like draining a lake with an eyedropper" metaphor far too often and it's time to shake things up a bit). I would buy a $30 bottle of Mg solution from the LFS and then end up dumping the entire bottle into my water change water to make it 1400. So now I just buy 20-30 lbs. of MgCl crystals from LittleSilverMax because it's a far more cost effective solution, costs me maybe $80 or whatever but I end up with enough to fill a 5g salt bucket which lasts 6 to 12 months. I end up adding 225ml of it (almost a full cup) to my makeup water to make 1400 and when I dose my tanks I found it surprising how much of it I would need to raise Mg by 100. I forget how much exactly (I write stuff like that down so that I don't need to remember it, consequently, I don't remember what it is when I'm writing a post like this. Sorry. )

So if you're using a commercially available product to dose Mg and just following the instructions of "one capful per X gallons", my bet is that this is just not enough to maintain Mg. It wasn't for me anyhow and I'd be surprised if that truly works for anyone.

Over time Mg will deplete just like Ca and Alk will. Think I've heard the addage that the depletion rate is roughly the same per week as it is for Ca or Alk per day.

I first bought the liquid stuff, but I found it pretty useless, so I am now using crystals http://www.petsandponds.com/en/aquar...p17157180.html. I didn't find out about Littlesilvermax until after I bought the big container. I dose a max of 1 tbsp per day to avoid shocking my corals (who told me they disapprove of larger MG swings). I generally dose 2-4 days per week.

[fishytime]

Try using this http://www.reeftime.com/reef-chemistry-calculator.asp ....it will tell you what you need to dose of each chemical to get your parameters balanced

[kien]

Your Calcium is 1500ppm ?? Wow, I have never seen anyone run calcium that high. Is that just how it comes out in your Salt Water mixes or do you dose to get your Calcium to that level?

[Delphinus]

Oooh ... good catch Kien. Calcium can't be 1500 that sounds way too high. I thought you meant 500 which is still quite high but not impossibly so. As for adjusting Mg you should be able to adjust by 100 per day, when I target Mg in my tanks I'll go whatever amount gets me a 100-150 rise in Mg and then just repeat that daily until I've hit 1400.

[c_scherer123]

Originally Posted by kien

Your Calcium is 1500ppm ?? Wow, I have never seen anyone run calcium that high. Is that just how it comes out in your Salt Water mixes or do you dose to get your Calcium to that level?

Good catch, it is a typo, I meant 500.

Salt is a mixture of "marine environment - superior two part" and "red sea coral pro salt". Each one has what the other tends to lack and so it balances out pretty well.

As for KH reading, after getting an absolutely ridiculous reading (50 - the test tube was almost full!), I checked the exp. date and it is 6 yrs past it. Just bought that kit in April too... Used it 3-4 times with KH always high around 10-12.

I also dose Kalk, and occasionally 2 part, with all RO water added. My calcium always used to be around 400 even with the dosing, and suddenly its stopped dropping.

I don't suppose that a bottle of tank water would last a 4 hour trip into the city and that the water values would remain unchanged? I might as well get the pet store to check it as well as buy a working test kit, at least then I will know if my other kits are working (all other exp. dates are looking good).

I am pretty sure it is an imbalance as suggested, I just need to figure out how the balance currently sits.

[Coleus]

Originally Posted by fishytime

Try using this http://www.reeftime.com/reef-chemistry-calculator.asp ....it will tell you what you need to dose of each chemical to get your parameters balanced

I have a question about the calculator and dosing mag.

Let's say my tank is 180 gallon in total (main + sump) and i am using Sea Chem Magnesium Advance and I would like to raise from 1300 to 1400

The calculator says the amount i need is 171 tsps; 855 grms; 30.15 oz


So, do i pour this whole amount into 10% of freshwater change or directly into the tank? Raising 100ppm per day is safe right?

Thanks

[e46er]

Don't forever to account for sand and water rock displacement