Hi
Then slowly increase it to 1300 ppm and try to keep it between 1250 and 1350 ppm by performing water changes, which will both help you to adjust KH, Ca and Mg.
From your readings you are in the zone 1 of calcium and alkalinty problems as explained in the
article Galantra suggested you to read
Randy Holmes Farley said:
Calcium and Alkalinity Problems
If your tank falls outside of these ranges for either or both of these measurements, then how you need to go about correcting them does indeed depend on the relationship between the two. It is this aspect of calcium and alkalinity maintenance that causes problems for many aquarists.
Figure 1. A graph showing possible values for calcium and alkalinity in marine aquaria. The red zone is the recommended target, and the blue dot represents values in natural seawater. Each numbered zone outside of the target area has a specific set of directions to get back to the target.
Figure 1 shows a graph of calcium and alkalinity for marine tanks. The red zone in the middle represents the desired range for both parameters. The blue dot represents the values present in natural seawater. We will use this figure to determine a course of action for each of the four numbered zones outside of the red target area. So the first step is to see where your tank falls on the graph, and then follow the directions given for that zone.
Corrections for Zone 1
Zone 1 is the easiest problem to correct. Unfortunately, it is also very uncommon. In this case, both calcium and alkalinity are on the high side of normal. Moreover, if you leave the tank alone, the problem will likely correct itself, and you will end up in the red target zone (though you may also pass through it into zone 2 if you wait too long).
Figure 2. A graph showing how to correct values within zone 1 by allowing calcium carbonate to be deposited in the tank (the blue arrow).
What this zone implies is that both calcium and alkalinity are elevated, and that by removing calcium carbonate from the water, either through biotic deposition into coral skeletons or coralline algae, or through abiotic precipitation, as on heaters, the levels of each will drop in an appropriate ratio. More specifically, the tank parameters will move along a line parallel to the two lines bordering this zone, and directly into the red target zone (the blue arrow in Figure 2). If you are smack in the middle between these two lines, as in Figure 2, then you will continue to move in the middle of these two lines down into the target zone.
This movement can continue right out the bottom end of the target zone (into zone 2), of course, so once you reach the target zone, you�ll have to reinitiate normal calcium and alkalinity additions.
Again the best way as suggested already to correct this, is by water changes.
Concerning the Magnesium levels of 1120 you have, if you chose to do it by using a magnesium additive,
which you should avoid as adding chemicals to the tank is always complicated, especially in the situation your water parameters are!!!, then do it over the course of 4 days at a rate of 50ppm a day or even longer until you reach 1300 ppm or 1320ppm (avoid keeping values at the lower or upper limit levels, so that you do not fall out of range should it go down or up),but again do it instead by means of water changes.
Magnesium is the third most abundant ion in sea water and plays a very important role in
balancing Alkalinity and Calcium and among other will help prevent disastrous precipitations as a result of the unbalance between the Ca and KH
Randy Holmes Farley said:
Magnesium is an important ion for reef aquarists. In addition to its many biological functions, it serves to prevent the excessive precipitation of calcium carbonate from both seawater and aquarium water. Since both calcium and alkalinity are very important to organisms that we keep, making sure that they are not lost to excessive precipitation is an important part of aquarium husbandry.
Now the value you read of 1120 ppm is or can be interpreted as being a result of calcium carbonate precipitation caused by the unbalance between Ca and KH,
Randy Holmes Farley said:
Sinks for Magnesium in Marine Aquaria
The primary sink for magnesium in aquaria is coprecipitation with calcium carbonate. This occurs in organisms, as shown in Table 1, and also during the abiotic (non-biologically driven) precipitation of calcium carbonate (such as on heaters).
so by increasing the Mg to the correct levels and lowering the Ca and KH,
this done through water changes, you will be both avoiding the risk of a tank crash in consequence of a "snowstorm" or "rain" caused by the sudden precipitacion of calcium carbonate and correct the levels of them all smoothely...so please do it through water changes, gradually, do not use any buffers or chemicals as you could end up in water parameter sudden swings.... Its simple, just perform gradual water changes
Randy Holmes Farley said:
Precipitation can begin when one of two things occurs:
Randy Holmes Farley said:
1. [FONT="] [/FONT] Calcium carbonate seed crystals are added to the water. In reef tanks, the addition of fresh calcium carbonate sand will often suffice. This addition will initiate the precipitation of calcium carbonate (likely containing some magnesium and strontium as well). 2. The supersaturation is pushed to unusually high levels. This can be caused by a rise in pH, a rise in temperature (as on a heater; Figure 1), or more obviously, by a rise in either calcium or carbonate.
Figure 4. An aquarium heater with a thin coating of calcium carbonate on the portions that get hot. This coating collected in a few months. After a year or two in the aquarium, this coating can become so thick that large chunks can be broken off.
Still from you explanation the cause for this is still unclear...you wrote that some one told you to keep values like that, but exactly what did you do eversince you started the tank?
About
Calcium and Alkalinity read some more from Randy Holmes Farley
About
Alkalinity read some more from Randy Holmes Farley
About
Calcium read some more from Randy Holmes Farley
Cheers
Pedro Nuno;-)