High Mag Usage?

[m3bimmerboy]

I just started using Randys 2 part about 2 months ago and have been doing regular tests etc. to try to figure out what my daily dosages will be. I do weekly tests then dose to my targets over the next 3 days. Test again and so on. Anyways after about 2 months I have gone through 1/2 Gal of Cal. / 1/4 Gal of Alk. / and 1 full Gal of Mag. Is this way out of whack? should my mag usage be that much more than the other 2? I thought Mag only needed to be dosed when you had used up the other 2? I dont think my system would survive that long. I am targeting 440 Cal. 3.9 Alk and 1350 Mag.
I am running a 90 Gal. system that is lightly stocked and 6 months old. Using Randy's recipe #1.

 

[drummereef]

Wha? You shouldn't be using near that amount of mag suppliment. What mag test kit are you using?

 

[m3bimmerboy]

SeaChem. I check it with the supplied testing solution and it is bang on. After I dose i test the tank and it is fine but the levels wont stay up.

 

[bertoni]

[welcome]

Many or all calcifying organisms also consume magnesium. Some consume more than others, with some coralline algae and corals consuming a fair amount:

http://www.advancedaquarist.com/issues/oct2003/chem.htm

That consumption rate might be a bit high, but a lot depends on the rate of water changes and the amount of 2-part dosed. Could you quantify those parameters?

 

[m3bimmerboy]

Water changes are now 10% every 1-2 weeks. But wasnt always this often. Using Seachem reef salt then switched to IO. Only growing Softies... Mushrooms, Cabbages, Toadstools, Frogspawn. Very light load. Latest test was mag 1200 tonight, going to need 1100ml to get it back to 1350ppm.

 

[bertoni]

One issue with IO is that the magnesium level is low, perhaps around 1100 ppm out of the box. Ca is likewise a bit low. The water changes will be reducing the Mg level if the IO isn't being supplemented before being used.

 

[Myka]

I tested my IO salt two weeks ago after being aerated for 24 hours using a Salifert test kit, and the Magnesium was bang on 1350. I do, however use RO water with a TDS of 1-4ppm.

I don't understand why when everyone tests their salt they come up with different answers. My best guess is minor human error...????

 

[bertoni]

I often wonder about that. I just don't know.

 

[jdieck]

If you started with low magnesium it will take a lot more magnesium supplement to reach the target than the other two because the magnesium is not consummed too fast the solution is rather diluted so when needs come to make a large adjustment it may need a lot to get there, but once there the requirement will be much smaller.
Try making a magnesium only adjustment, use the claculator to determine how much solution you need; you can increase up to 100 ppm per day.
http://home.comcast.net/~jdieck1/chem_calc3.html

 

[jdieck]

<a href=showthread.php?s=&postid=10172604#post10172604 target=_blank>Originally posted</a> by Myka
I tested my IO salt two weeks ago after being aerated for 24 hours using a Salifert test kit, and the Magnesium was bang on 1350. I do, however use RO water with a TDS of 1-4ppm.

I don't understand why when everyone tests their salt they come up with different answers. My best guess is minor human error...????

Most people does not account for diferences in the salinity of the mix. We think testing is equivalent but most of the time we fail to indicate at which salinity the parameters were measured.

 

[m3bimmerboy]

<a href=showthread.php?s=&postid=10169209#post10169209 target=_blank>Originally posted</a> by bertoni
One issue with IO is that the magnesium level is low, perhaps around 1100 ppm out of the box. Ca is likewise a bit low. The water changes will be reducing the Mg level if the IO isn't being supplemented before being used.

I suppliment my IO so that it equals my target levels for the tank. I test each new bucket od salt that i start.

 

[bertoni]

Interesting. 1/2 gallon of calcium and one gallon of Mg? Is there any chance that the Mg solution isn't full strength? Do you supplement the IO with the solution or directly with solids?

 

[m3bimmerboy]

<a href=showthread.php?s=&postid=10173925#post10173925 target=_blank>Originally posted</a> by jdieck
If you started with low magnesium it will take a lot more magnesium supplement to reach the target than the other two because the magnesium is not consummed too fast the solution is rather diluted so when needs come to make a large adjustment it may need a lot to get there, but once there the requirement will be much smaller.
Try making a magnesium only adjustment, use the claculator to determine how much solution you need; you can increase up to 100 ppm per day.
http://home.comcast.net/~jdieck1/chem_calc3.html

Yes I am using the calculator, I am currently trying to suppliment my mag up 150 ppm

 

[Billybeau1]

That almost never works, unless you are doing continual water changes.

If you change water even once a week, how do you offset the drop in calcium and alkalinity in that given week ?

 

[m3bimmerboy]

<a href=showthread.php?s=&postid=10175157#post10175157 target=_blank>Originally posted</a> by bertoni
Interesting. 1/2 gallon of calcium and one gallon of Mg? Is there any chance that the Mg solution isn't full strength? Do you supplement the IO with the solution or directly with solids?

I mixed all of the solutions according to Randy's recipies and I am supplimenting the IO with the solutions. My current levels for a fresh mix of IO are Cal 340 , Alk 3.4, Mag 1100. I am using RODI water with a TDS reading of 0

 

[m3bimmerboy]

<a href=showthread.php?s=&postid=10175173#post10175173 target=_blank>Originally posted</a> by Billybeau1
That almost never works, unless you are doing continual water changes.

If you change water even once a week, how do you offset the drop in calcium and alkalinity in that given week ?

I suppliment the tank directly according to my tests. I just always make sure the new water I add is already at my Targets. I would have thought that with my coral load my usage would have been really low.

 

[bertoni]

Okay, very interesting. I'd guess the test kit is okay, because it sounds as if the new saltwater supplementation has been tested and is working. That's a fair amount of magnesium. As long as the animals look okay, I wouldn't worry too much, but a second opinion on the Mg test kit wouldn't hurt, if that's easy to do.

The 1/4 gallon of alkalinity vs the 1/2 gallon of calcium is odd, as well.

I guess I'll have to think some more.

 

[m3bimmerboy]

My biggest concern I guess is that the instructions said to add 1 1/2 cups when you finish using 1 gal of the Cal and Alk. Mine seems to be going in the opposite direction and I was concerned if this was something to be concerned with. My tank is fairly new and I am new to the hobby so I am testing all of my levels Weekly.

 

[bertoni]

That part of the instructions is mostly for tanks which don't get frequent water changes. I don't mix the magnesium part, personally, since my water change rate is high enough that using it doesn't make all that much sense.

 

[m3bimmerboy]

Is it possible that it is precipitating onto my sand bed and rock?