Those seem fine to me, unless it is a ULNS system then alk may be too high.
Here's my discussion of those parameters from another thread:
Optimal Parameters for a Coral Reef Aquarium
By Randy Holmes-Farley
One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There are many different attributes of the aquarium that need to be controlled, including lighting, water flow, temperature, and the concentrations of the many chemicals in the water. This article focuses on water chemistry issues, showing my recommendations for the most important of the various chemical parameters in a reef aquarium.
Table 1 shows a summary of some of the most important water parameters for reef aquaria. Table 2 shows some of the less critical parameters, or those too complicated for many aquarists to carefully control, but about which many aquarists have concerns or questions. The remainder of this article provides the rational and further discussion for each of the parameters in these tables.
A detailed discussion of an individual parameter could fill an entire article, and so the commentary here is necessarily abbreviated. For further discussion, you can ask me questions in the Reef Chemistry Forum at Reef2Reef:
Reef Chemistry by Randy Holmes-Farley
Some aquarists have begun to focus more on the measurement of trace elements (i.e., those that are present at very low levels, such as iron or copper). With the exception of iron, which has a long history of utility in dosing, I will not go into these other trace elements at this time because the methods to measure and control them are not as simple as the other ions in this paper.
Table 1. Parameters critical to control in reef aquaria.
Table 2. Other parameters in reef aquaria that aquarists may want to control.
* I do not generally recommend measuring and controlling these parameters, but if you do, these are the guidelines.
Critical Parameters
Calcium
Many corals use calcium to form their skeletons, which are composed primarily of calcium carbonate. The corals get most of the calcium for this process from the surrounding water. Consequently, calcium often becomes depleted in aquaria housing rapidly growing corals, calcareous red algae (coralline algae), Tridacnids (clams) and Halimeda (a macroalgae containing calcium carbonate). As the calcium level drops below 360 ppm, it becomes progressively more difficult for these organisms to collect enough calcium, thus stunting their growth.
Maintaining the calcium level is one of the most important aspects of coral reef aquarium husbandry. Most reef aquarists try to maintain approximately natural levels of calcium in their aquaria (~420 ppm). It does not appear that boosting the calcium concentration above natural levels enhances calcification (i.e., skeletal growth) in most corals.
For these reasons, I suggest that aquarists maintain a calcium level between about 380 and 450 ppm, although higher is generally not a problem until it gets so high that calcium carbonate precipitation becomes problematic. Aquarists with a very light demand may be able to maintain calcium with water changes, especially since some salt mixes have excessive calcium in them. But most established aquaria with growing hard corals and coralline algae will require some calcium supplementation, and in some cases, it might be needed every day.
I usually suggest using a balanced calcium and alkalinity additive system for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part or three-part additive systems for calcium and alkalinity. If calcium is depleted and needs to be raised significantly, however, such balanced methods are not a good choice since they will raise alkalinity too much. In that case, adding calcium chloride is a good method for raising calcium in a one-time correction.
Alkalinity
Like calcium, many corals also use "alkalinity" to form their skeletons, which are composed primarily of calcium carbonate. It is generally believed that corals take up bicarbonate, convert it into carbonate, and then use that carbonate to form calcium carbonate skeletons. That conversion process is shown as:
HCO3- → CO3-- + H+
Bicarbonate → Carbonate + proton (which is released from the coral)
To ensure that corals have an adequate supply of bicarbonate for calcification, aquarists could just measure bicarbonate directly. Designing a test kit for bicarbonate, however, is somewhat more complicated than for alkalinity. Consequently, the use of alkalinity as a surrogate measure for bicarbonate is deeply entrenched in the reef aquarium hobby.
So, what is alkalinity? Alkalinity in a marine aquarium is simply a measure of the amount of acid (H+) required to reduce the pH to about 4.5, where all bicarbonate is converted into carbonic acid as follows:
HCO3- + H+ → H2CO3
The amount of acid needed is equal to the amount of bicarbonate present, so when performing an alkalinity titration with a test kit, you are “counting†the number of bicarbonate ions present. It is not, however, quite that simple since some other ions also take up acid during the titration. Both borate and carbonate also contribute to the measurement of alkalinity, but the bicarbonate dominates these other ions since they are generally lower in concentration than bicarbonate. So knowing the total alkalinity is akin to, but not exactly the same as, knowing how much bicarbonate is available to corals. In any case, total alkalinity is the standard that aquarists use for this purpose.
Unlike the calcium concentration, it is widely believed that certain organisms calcify more quickly at alkalinity levels higher than those in normal seawater. This result has also been demonstrated in the scientific literature, which has shown that adding bicarbonate to seawater increases the rate of calcification in some corals. Uptake of bicarbonate can consequently become rate limiting in many corals. This may be partly due to the fact that the external bicarbonate concentration is not large to begin with (relative to, for example, the calcium concentration, which is effectively about 5 times higher).
For these reasons, alkalinity maintenance is a critical aspect of coral reef aquarium husbandry. In the absence of supplementation, alkalinity will rapidly drop as corals use up much of what is present in seawater. Water changes are not usually sufficient to maintain alkalinity unless there is very little calcification taking place. Most reef aquarists try to maintain alkalinity at levels at or slightly above those of normal seawater, although exactly what levels different aquarists target depends a bit on the goals of their aquaria.
Interestingly, because some corals may calcify faster at higher alkalinity levels, and because the abiotic (nonbiological) precipitation of calcium carbonate on heaters and pumps also rises as alkalinity rises, the demand for alkalinity (and calcium) rises as the alkalinity rises. So an aquarist generally must dose more calcium and alkalinity EVERY DAY to maintain a higher alkalinity (say, 11 dKH) than to maintain 7 dKH. It is not just a one-time boost that is needed to make up that difference. In fact, calcification gets so slow as the alkalinity drops below 6 dKH that reef aquaria rarely get much below that point, even with no dosing: natural calcification has nearly stopped at that level.
In general, I suggest that aquarists maintain alkalinity between about 7-11 dKH (2.5 and 4 meq/L; 125-200 ppm CaCO3 equivalents). Many aquarists growing SPS corals and using Ultra Low Nutrient Systems (ULNS) have found that the corals suffer from “burnt tips†if the alkalinity is too high or changes too much. It is not at all clear why this is the case, but such aquaria are better served by alkalinity in the 7-8 dKH range.
As mentioned above, alkalinity levels above those in natural seawater increase the abiotic precipitation of calcium carbonate on warm objects such as heaters and pump impellers, or sometimes even in sand beds. This precipitation not only wastes calcium and alkalinity that aquarists are carefully adding, but it also increases equipment maintenance requirements and can “damage†a sand bed, hardening it into a chunk of limestone. When elevated alkalinity is driving this precipitation, it can also depress the calcium level. An excessively high alkalinity level can therefore create undesirable consequences.
I suggest that aquarists use a balanced calcium and alkalinity additive system of some sort for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part/three part additive systems.
For rapid alkalinity corrections, aquarists can simply use baking soda (sodium bicarbonate) or washing soda (sodium carbonate; baked baking soda) to good effect. The latter raises pH as well as alkalinity while the former has a very small pH lowering effect. Mixtures can also be used, and are what many hobby chemical supply companies sell as “buffersâ€. Most often, sodium carbonate is preferred, however, since most tanks can be helped by a pH boost.
Magnesium
Magnesium's primary importance is its interaction with the calcium and alkalinity balance in reef aquaria. Seawater and reef aquarium water are always supersaturated with calcium carbonate. That is, the solution's calcium and carbonate levels exceed the amount that the water can hold at equilibrium. How can that be? Magnesium is a big part of the answer. Whenever calcium carbonate begins to precipitate, magnesium binds to the growing surface of the calcium carbonate crystals. The magnesium effectively clogs the growing crystal surface so that they no longer look like calcium carbonate, making it unable to attract more calcium and carbonate, so the precipitation stops. Without the magnesium, the abiotic (nonbiological) precipitation of calcium carbonate would likely increase enough to prohibit the maintenance of calcium and alkalinity at natural levels.
For this reason, I suggest targeting the natural seawater concentration of magnesium: ~1285 ppm. For practical purposes, 1250-1350 ppm is fine, and levels slightly outside that range (1250-1400 ppm) are also likely acceptable. Higher levels may be fine, but there is no reason to keep it higher, with the possible exception of trying to kill bryopsis with certain magnesium supplements (which may work due to an impurity rather than the magnesium itself). I would not suggest raising magnesium by more than 100 ppm per day under normal conditions, in case the magnesium supplement contains any toxic impurities. If you need to raise it by several hundred ppm, spreading the addition over several days will allow you to more accurately reach the target concentration, and might possibly allow the aquarium to handle any impurities that the supplement contains (such as ammonia or trace metals).
An aquarium's corals and coralline algae can deplete magnesium by incorporating it into their growing calcium carbonate skeletons. Many methods of supplementing calcium and alkalinity may not deliver enough magnesium to maintain it at a normal level. Settled limewater (kalkwasser), for example, is quite deficient in magnesium relative to a coral skeleton. Consequently, magnesium should be measured occasionally, particularly if the aquarium's calcium and alkalinity levels seem difficult to maintain. Aquaria with excessive abiotic precipitation of calcium carbonate on objects such as heaters and pumps might suffer from low magnesium levels (along with high pH, calcium, and alkalinity). In general, magnesium is usually depleted at roughly 10% of the rate of calcium depletion, or less, depending on the creatures in the aquarium. Any depletion rate that is much higher than that is either due to testing errors, or water changes with a mix that has a different magnesium level than the aquarium.
Many people never need any magnesium supplements. Some salt mixes start so high that it will never drop below natural levels, and some calcium and alkalinity supplement methods, such as a good quality two part system, add enough magnesium that it should not decline.
