I hate water chemistry

[Randy Holmes-Farley]

Randy,

So you are saying if my alkalinity dosing becomes steady at 24 ml per day I should dose 24 ml of calcium as well?

Yes, unless it is actually ALREADY higher or lower than you want. That addition will keep calcium about where it is.

If it is already too high, stop dosing any calcium until it drops back to where you want it.

If it is tioo low, make a one time boost with extra calcium chloride,a nd then continue as planned.

If, somehow, you determine that a different daily dose of calcium is appropriate (to offset changes due to water changes, for example), then it is fine to dose a different amount daily. But in general, pick a dose and stick with it rather than continually adjusting based on calcium measurements every few days. There is just too much variability in calcium testing for that to be optimal (but in a perfect world with perfect test kits used perfectly, it would be fine).

 

[Randy Holmes-Farley]

Yes. I bet randy has answered that question 100 times in the past two weeks (I asked the same question).

Imagine how many times in the past 19 years.

 

[Bernardhny]

So far it is pretty good. My ppm for alk is 184 and calcium sticks around 425. That is after about 8 days since my last water change. I kinda feel it is dialed in.

 

[Randy Holmes-Farley]

So far it is pretty good. My ppm for alk is 184 and calcium sticks around 425. That is after about 8 days since my last water change. I kinda feel it is dialed in.

That sounds good.

 

[Bernardhny]

Yea but I am far from dosing equal parts. Calcium I am dosing 60 ml per day and alk is only doing 25 ml per day. I can't drop the calcium dose to the alk or go the other way. Far from equal dosing which makes me wonder if I am doing something wrong

 

[Randy Holmes-Farley]

Yea but I am far from dosing equal parts. Calcium I am dosing 60 ml per day and alk is only doing 25 ml per day. I can't drop the calcium dose to the alk or go the other way. Far from equal dosing which makes me wonder if I am doing something wrong

As long as you are dosing a steady amount and calcium is where you want it, uneven dosing is fine.

What salt mix do you use for water changes?

 

[Bernardhny]

I am using red sea coral pro. I change every Friday but missed this last change

 

[Randy Holmes-Farley]

Well, that is a very high alkalinity salt mix, so that might be part of the issue.

 

[Bernardhny]

My alk drops quickly in the tank even with doing 10g changes weekly. It has always been an issue. Magnesium has always been good with water changes and calcium started dropping more as of late.

 

[Randy Holmes-Farley]

Alkalinity dropping is normally a sign of a healthy, growing reef.

 

[zemuss]

If you have a UNLS what are the ideal ALK parameters? I usually shoot for 8 - 9 dkh

 

[Randy Holmes-Farley]

I don't have a recommended ideal for a ULNS SPS system, but avoid higher alk (say, 10+ dKH) and keeping it fairly stable may also be more desirable than ordinary reef aquaria.

Some prefer 7-8 dKH for those systems, but it all boils down to "burnt tip" issues, and if you do not have such issues, then you will likely not benefit from lower alkalinity than whatever it is now.

Here's my full rundown on alkalinity (and other parameters in the link):

https://www.reef2reef.com/forums/re...-coral-reef-aquarium-randy-holmes-farley.html

from it:
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 “buffers”. Most often, sodium carbonate is preferred, however, since most tanks can be helped by a pH boost.