I ran into this as well after dosing AFR for ~2 months. ALK and CA would differ and I ended up having to always adjust the AFR dose or manually adjust ALK or CA. I think this is expected, from interviews I've heard of Lou Ekus from TM on BRS podcast. So I switched to RS 7 part and am happy. Considered their 4 part but its really the same as AFR in my opinion since they are all linked dosing wise on CA.
Idk I have bee using AFR for almost a year now, and I don't really see alot of growth and color in my corals, my parameters are pretty good, ph.8.1 alk 9.5 cal 430 mag 1360 phos .01 nitrate 5, I was just really wondering about the trace elements, as I am only dosing 14mls a day of afr in my 90gallon.
Hope your day is well Miami!
www.reef2reef.com
Thanks a lot!I discuss ionic balance issues caused by dosing calcium chloride and sodium bicarbonate/carbonate/hydroxide here:
How a Two Part Alkalinity and Calcium System Works, and Why it Matters
How a Two Part Alkalinity and Calcium System Works, and Why it Matters By Randy Holmes-Farley This article is intended to help aquarists understand some of the important differences between the great variety of two and three part alkalinity and...
from it:
Accumulating Sodium and Chloride
A very important consequence of using a two part is that sodium and chloride are added with every dose. Over time, this effect is quite significant. The actual salinity increase will vary based on exactly what other ingredients are incorporated into the two part, and in what form, but we can estimate the minimum effect one would see without water changes from just the alkalinity and calcium additions.
Assumption: add 1 dKH of alkalinity and the balanced amount of 7 ppm calcium each day. 1 dKH of alkalinity causes 0.36 meq/L of sodium to accumulate, or 8 mg/L sodium. The calcium chloride addition will add 12.4 ppm of chloride. Importantly, the Na to Cl ratio is exactly that found in NaCl, and we will come back to that later. We are thus adding 8 + 12.4 mg/l every day, or 632 mg/L in a month = 0.63 ppt each month =7.5 ppt in a year. Note that this is a minimum effect and does not count additions of other ions that may be present, such as sulfate.
This salinity rise means that aquarists may have to offset that rise by removing some salt water periodically and replacing it with fresh. It may happen partly by skimming, but will also likely require some intervention. Do not rely on the above number for intervention purposes because some two parts may contain much more material (e.g., sulfate, etc.). Make the changes as you would for any other factor impacting salinity: by testing and adjusting when needed).
Further, when one lowers the salinity to offset the rise from the accumulating sodium and chloride, one is necessarily depressing every other ion in the water. For example, if you dose at the 1 dKH per day rate, do no water changes, then after a year drop the salinity by 7.5 ppt, the concentration of every ion in the water will drop by a factor of (35-7.5 ppt)/(35 ppt) to 79% of its value on the first of the year. Potassium, for example, would drop from 400 ppm to 316 pm. Even worse, magnesium is not only depressed by this factor (1300 ppm to 1027 ppm) but was also getting consumed along the way.
Water changes will reduce these problems, but most two part systems try to deal with them directly in any of several ways that are discussed in the next section.
Ion Balance
There are three fundamentally different ways to dealing with the ion imbalances and reductions caused by the accumulating sodium and chloride and subsequent salinity adjustments. These are:
1. Incorporating some or all ions impacted by this issue into one of the two parts of a two part system. This method is used by ESV B-ionic and a number of other brands. I have never seen any data of any sort that shows how well any manufacturer implements this method, and to elect a commercial system of this sort requires a substantial amount of trust that they know what they are doing, and then also did it properly. There are also some DIY recipes that use this method, though they are typically limited in the number of ions used.
This overall procedure involves more than just adding what was taken out in the salinity correction because sodium and chloride actually rise more than the salinity overall. In our example above, salinity rose by 7.5 ppt (21%) over a year, while sodium rose by 8 mg/L per day = 2920 mg/L in a year, which is approximately 10,800 mg/L to 13720 mg/L, or a 27% rise. Thus, even if we correct salinity back by 21%, sodium will still be high and everything else (except chloride) will be a bit low. To keep the water looking like seawater, one needs to add back even more of the ions that were depressed, which in turn raises salinity again, which in turn needs another correction. One can solve this problem on a spread sheet, and I won’t go into the complexity. That complexity, however, is a reason to only use a two part where you have confidence that the employees of the company are able to understand and deal with that complexity in design.
The other aspect of this design is deciding what forms of the ions can be put into which part of the two part. Sulfate is the biggest mass additive in this procedure, and it must be put into the alkalinity part because putting it into the calcium part results in precipitation of calcium sulfate. The designers also need to decide how to add it. It is likely all sodium sulfate, (boosting sodium again) or it could partly be potassium sulfate and other ions. In short, it’s a logic puzzle for chemists to decide what can be put where for the lowest cost and best performance. Since there are potentially dozens of chemicals to worry about, it is a nontrivial problem.
2. A second method involves using a third part intended to correct these ion imbalances. This method is technically simpler than #1 since one is not deciding what can go where.
Commercial approaches in this regard include Tropic Marin Balling Part C and Aquaforest Reef Mineral Salt as the third part. These are artificial sea salt mixes without the sodium chloride, and are seemingly easy for a salt mix manufacturer to make correctly. The reason such a system can work is that, as noted above, the accumulating sodium and chloride are in the same ratio as in sodium chloride. Sodium chloride is the biggest ingredient in any salt mix (it must be), but if it is left out, and combined with the accumulating sodium chloride from use of the alkalinity and calcium parts, one can have a residue that matches the original salt mix in all aspects.
These third parts work equally well whether the alkalinity part is sodium bicarbonate, or carbonate or hydroxide, since all add the same amount of sodium per unit of alkalinity added. They are thus easily combined with any other two part, such as a DIY, to take a hybrid approach to save costs or to use sodium hydroxide for the alkalinity part.
One minor point is that while conceptually this works out well, if one is doing water changes along the way, between when the excess sodium and chloride were added and when the third part is added and salinity is corrected, the final effect will not be perfect. I think this effect is quite minor unless one waits a long time before making the adjustments. Ideally, one would frequently be adding this third part. The amount to use will depend on how much of the other two parts are being used.
Another issue is that use of sodium chloride free salt cannot offset ANY consumption of ions, such as magnesium or trace elements, unless it is not actually sodium chloride free salt as both companies claim, and those ions may need to be added in some other fashion.
Finally, it is not clear to me whether these mixtures actually contain calcium or alkalinity. If they do, as they seeming claim from the description, that may limit how concentrated they can be made for dosing (due to calcium sulfate and carbonate precipitation), but my guess is they leave them out without telling folks. That issue does not really concern a user either way since they will be dosing and controlling calcium and alkalinity anyway.
There are DIY recipes for this part 3, and my DIY two part recipes do include a third part. In my recipe, this third part is primarily designed to deal with magnesium and sulfate depletion, and is not focused on many other ions (such as bromide). They are cheaper, and many users have shown them adequate over the many years they have been used, especially when also doing water changes, but they are clearly less complete than the sodium chloride free salt mixes described above.
3. Ion balance by water change. A third approach is to use just the alkalinity and calcium parts described above (with no additional ions in them) and to rely on water changes to make up any corrections. This approach is clearly the least expensive for the additives, but may be substantial in costs for water changes. Many years ago, Craig Bingman modelled the effects of this system in two articles (#1 and #2)and came to this conclusion:
