In modern magnesium chloride has been favoured as a result of cellular research. They showed the cells accessed magnesium chloride more readily and that sulphate contributed to an inhibited response.
FWIW, that makes no sense in the context of seawater supplement. The chloride and sulfate in seawater are totally dissociated from the magnesium. The magnesium retains no history of where it came from after less than a millisecond in the seawater.
For Randy, your Two Part method hadn't included sulphate either? Which gave way to the Three Part method I assume.
I never made a two part that didn't include magnesium sulfate. But yes, it needs to be a three part system if magnesium sulfate is all or a part of the source of magnesium. Magnesium sulfate cannot be put into the calcium part because calcium sulfate will precipitate, and it cannot be put into the alk part because magnesium hydroxide and/or carbonate will precipitate.
If the introduction of sulphate to the aquarium on mass is by magnesium alone then what happens in an aquarium with a background demand on magnesium?
Not sure I understand. Sulfate is a big part of the salt mix, so there is sulfate in natural and artificial seawater. One need only add more sulfate if you are adding a lot of chloride for some reason, like calcium chloride as a calcium supplement. If you use limewater (kalkwasser) or a CaCO3/CO2 reactor, there is no need for adding any additional sulfate.
Certainly magnesium is used by animals but it's exact amount is variable substantially both by organisms themselves, also in response to environmental changes which is recorded +/- 20% (incredible changes)
Very little use by most organisms except bacteria. Not enough to deplete a seawater aquarium by consumption, IMO, since it starts so high and it can result when foods are fully digested by bacteria.
Calcium and carbonate seems more consistent measured amount in it's usage.
Yes, that usage by corals to produce their skeletons is far, far higher.
As Bertoni suggests that trace elements could be supplemented without the use of additional bottles by means of a water change alone, surely this gives way to the same analogy for other chemical components.
Not sure what you mean. If you mean putting sulfate in a trace element cocktail, that could be done despite the fact the sulfate is not a trace element. It is the third most abundant ion in seawater by mass. But that said, since the depletion is not by consumption but only by displacement when using calcium and magnesium chloride as supplements, adding "some" by a trace element supplement doesn't really make sense since how would you know how much to add? Putting it into the two part recipe solves that problem entirely since the amount you need depends exactly on how much two part additive you use.
If you can quantify a specific demand for magnesium within a broad range of aquariums, then advocating the addition of sulphate purely for the perspective of ionic balance could be plausible. Although while doing so, could you show a tank that suffered detriment from ionic imbalance by advanced depletion?
As I mentioned, a two part without sulfate causes sulfate depletion without and in tank demand at all, and that depletion is far, far higher than any consumption. It is easy to quantify, and that is why it is easy to determine how much to put into a two part.
Outside of mathematical simulations and hypotheses, in both long or short term aquariums (without going to extremes) or by means of user error, to my knowledge so far and to this day no such aquarium exists.
I've never seen anyone measure sulfate or chloride in aquaria themselves and track deviations back to the methods used to supplement calcium and alkalinity. So I agree there is no tank data. However, that a two part without sulfate necessarily depletes sulfate goes totally without question once you understand why it is depleting. Do you disagree with this? You may disagree with my published mathematical calculation of the effect, but do you disagree with the entire premise that it must happen?
IMO, it is akin to saying if you open a nitrogen gas cylinder in a room with somewhat leaky windows, oxygen will decline as it is displaced from the room by N2. One does not need to measure it to be confident that it will happen.
In contrast, by accumulation, there are examples of how the persistent addition of compounds generally have contributed to difficulties faced by some aquarists.
What a strange comment if you intend it to apply to sulfate in a two part. EVERY commercial two part that claims to leave a seawater residue contains sulfate (and necessarily the same amount mine does). The added sulfate in mine just makes it closer to commercial products. The really strange thing is that Fauna chooses not do so when everyone else does it for clearly understood reasons.
