magnesium precipitation?

[dadonoflaw]

i recently started to drip kalk a few weeks ago. my tank has been up for 8 mths. before i started with kalk my magnesium level was about 1500ppm for several months. now it is at 990ppm and i have been using the reef calculator to determine dosage and it says dose 153 fl oz. now i cant keep it up. whats wrong?

[Percula9]

What is the calcium level? Do you perform regular water changes?

[dadonoflaw]

water changes arent as regular as i would like. about once a month or so. calcium is at 300 right now so i just dosed some calcium into the water. is it that the kalk isnt keeping up or that its precipitating too fast to maintain it at a higher level?

[bertoni]

The magnesium level in the freshly-mixed saltwater might be low. That's true in a number of products, and is worth testing.

Kalk often can't meet the demand for calcium and alkalinity in tanks. A 2-part or a calcium reactor might be needed, as well. What's the alkalinity level?

I'd double-check the Mg test result, and then dose the tank to about 1300 ppm, raising Mg no more than 100 ppm per day. Once calcium, alkalinity, and magnesium are in line, the tank should be okay.

Once we know the Mg level in the salt product and get some idea of the calcium carbonate consumption, we might be able to see whether the Mg consumption is reasonable.

[dadonoflaw]

well i dont depend on my salt for mag. i use the third part with epsom salt and mag flake. i also will bump up the two part for ca and alk. i did a test with a salifert kit dated for 2009 3 time in two days and got a 60ppm loss in one day. seems like alot of mag in one day

[Meisen]

you wont be able to get the Mg up if the Ca or Alk are too high either. Mg is the first to precipitate when the Alk is elevated (its mostly what you see when you add an alk supplement....precipitating MgCl2)

[bertoni]

The reason I suggest checking the salt is that water changes might be driving down the magnesium level.

The level of depletion of Mg you mentioned is very large. What was the calcium level at that point, and how did it change?

[dadonoflaw]

ok i will test the make up water. i didnt check the ca then it was 300 today so i will check it tomorrow and see how much is gone. yea i thought that was alot. between corraline algae growth and precipitation i will be dosing alot of mag. is the kalk dosing making some mag precipitate directly out side of elevated alk levels?

[bertoni]

Kalk might cause calcium carbonate to precipitate, and that would take at least some magnesium with it, but the results should be visible powder or a coating inside the pumps, etc, at least if much is actually precipitating.

[dadonoflaw]

well i havent seen any precipitation on pumps or heaters so thats why i am somewhat puzzled but i will test tomorrow so i am curious

[dadonoflaw]

mag is 1500 today so thats good. cal is low but i can handle that

[Billybeau1]

Test kit or user error.

Do you have any idea how much magnesium supplement it takes to raise mag from 990 to 1500 in a 180 gal tank ?

Magnesium depletes rather slowly....... kalk or not.

What salt mix do you use ?

[dadonoflaw]

i use IO salt. i tested the numbers several times and got the same reading but i didnt get it tested elsewhere. it took about 10 cups of magnesium supplement to do it