Your new Sulawesi tank is full of RO water, and the bag of Sulawesi mineral salt is still sitting unopened next to it. You do need that bag: a Sulawesi tank is normally built from reverse osmosis water plus a Sulawesi-specific mineral salt, and the salt is what turns pure water into water these shrimp can live in. It isn’t an extra on top of the water. What it doesn’t mean is dosing minerals into a tank that’s already running.

Is hard tap water enough for a Sulawesi shrimp tank?

Almost never, and the reason is repeatability more than hardness. A Sulawesi tank is a narrow, alkaline, mineral-moderate target that you have to hit again every time you mix change water. Tap water is a moving supply. Hardness and carbonate hardness shift with the season and the source, and treatment chemistry varies by utility. So the number you measured in March isn’t a number you can plan around in September.

Two other things push keepers off tap water for this group. Copper reaches aquarium water through plumbing and through some treatments, and copper is harmful to shrimp and snails, so a supply you can’t characterize is a risk you can’t size. And even a tap supply that happens to land inside the range arrives with whatever else is dissolved in it, which makes a bad reading hard to trace later. Starting from RO water and building up is slower on day one. It’s far easier for the next two years. The upfront mixing is set out step by step in how to remineralize RO water for Sulawesi shrimp.

On well water, or a supply you know well that genuinely sits in the range below? Test it over several months before you trust it, and dechlorinate whatever you use. That’s a much bigger commitment than buying a bag of salt.

Can food or a cuttlebone replace a mineral supplement?

No, and this is the part that decides the whole question. Shrimp grow by casting the old shell and building a new one, which is a repeating event.¹ Most of the calcium for that new shell comes from the water the animal lives in, and food, including a shed shell the animal eats, adds only a minor share.²

So a calcium block, a mineral-enriched food or a clay powder is working on the small share at best. If the water itself is thin, none of them fixes it. That’s why “do they need mineral supplements” is a water question and not a feeding question. It’s also why keepers who add a supplement food to a poorly mineralized tank usually see nothing change.

What a Sulawesi mineral has to put into the water

Enough hardness and carbonate buffer to bring your change water into the Sulawesi range and hold it there. That’s the one job. These are the targets for Sulawesi shrimp, and they’re what a finished mix should read on your own test kit before it goes anywhere near a tank.

Water targets a Sulawesi mineral has to produce
pH	7.5-8.5
GH	4-8 dGH
KH	3-6 dKH
TDS	150-250 ppm

The carbonate half is the part people underrate. Alkalinity is the water’s capacity to neutralize acid and so hold a fairly stable pH.³ It comes from dissolved bicarbonates, carbonates and hydroxides.³ A Sulawesi salt has to supply that buffer at the same time as it supplies general hardness. Without it, the pH of the alkaline water Sulawesi shrimp need has nothing holding it up. And pH that moves is worse for a colony than pH that sits slightly off.

Difficulty is worth stating plainly here: this group is advanced to expert, and most of the difficulty is exactly this, holding a mixed-water target steady for months.

Why a Bee shrimp GH+ mineral is the wrong salt for a Sulawesi tank

A Bee shrimp GH+ mineral is built for soft, acidic water, so it lands a Sulawesi tank on the wrong target. A Bee shrimp tank runs pH 5.8-6.8, KH 0-2 dKH and TDS 100-150 ppm. A salt made for that water raises general hardness without building carbonate hardness, so the water it produces has almost no buffer in it. Put that in a Sulawesi tank and you’ve got hardness with nothing holding the pH up, which is the one thing this group can’t tolerate. Sharing the genus Caridina doesn’t make Bee and Crystal Caridina and Sulawesi shrimp share the same water. Same surname, different kitchens.

What about a general Neocaridina salt? It’s closer, since that recipe does carry carbonate hardness. But it’s aimed at a cooler, near-neutral tank, not an alkaline lake one, so it won’t land you where you need to be either. Crushed coral and aragonite are a different thing again. They’re a hardscape and substrate decision, not a measured dose you can mix, test and repeat, so they belong with choosing the best rocks for Sulawesi shrimp, not with this question.

Sulawesi Mineral 7.5 or 8.5: which one your setup can handle

Pick the one whose mixing routine you can keep up: the 7.5 salt dissolves in seconds and is ready to use, while the 8.5 salt needs CO2 and several days. Both of the widely available Sulawesi salts are made for remineralizing RO water, rainwater or fully desalinated water. The real difference between them is how much equipment and how many days it takes to get the powder into solution.

What the manufacturer states about the two Sulawesi mineral salts
Property	Sulawesi Mineral 7.5	Sulawesi Mineral 8.5
Dissolving	Almost totally dissolves within seconds, and the water is ready for use immediately	Almost totally dissolves only if CO2 is added, roughly 3-4 days at about one bubble per second
Step before the water is used	None stated	Aerate for at least three hours with an air stone to expel the CO2
Stated buffering	Buffers the pH at around 7.5	Recommended in place of the 7.5 salt for the more susceptible Lake Towuti species
Carbonate to hardness ratio	KH/dH = 0.42/1.0	KH/dH = 0.78/1.0
Species named on the product page	Lake Matano, Poso and Towuti species including Caridina dennerli and Caridina woltereckae⁴	Less finicky Sulawesi shrimp such as Caridina dennerli have been kept and bred with both salts⁵

Read the first two rows together and the decision usually makes itself. The 7.5 salt is mixed in a bucket and used the same hour, a routine you can keep up every week for years. The 8.5 salt gives more carbonate for the same total hardness, and it’s the one aimed at the touchier lake species. But it needs a CO2 source, a dedicated mixing vessel and most of a week of lead time before every water change, with the aeration step on top. If you can’t hold that routine, you’ll end up doing water changes late or not at all, and that costs the colony more than the difference between the two salts ever gains it.

The 7.5 salt also buffers at the bottom of the group range of pH 7.5-8.5. Keeping a line you want held higher in that band? That’s the argument for the 8.5 route and for the equipment that comes with it.

At Shrimp Aquatics, we start our Sulawesi systems with RO water rather than tap water, then use Sulawesi Mineral 7.5 to prepare the water for our current tank targets before shrimp are introduced. We test the finished pH, GH and TDS before the water goes into a tank.

Do you keep dosing minerals once the Sulawesi tank is running?

Not into the tank, no. In a running system the minerals go into the change water, which you mix to the same target every time. Nothing goes into the display except water that has already been measured.

Evaporation is why the two aren’t the same. As a matter of physical chemistry, evaporation concentrates the dissolved solids in the water that’s left behind.⁶ A warm, open aquarium loses water that way every day, so what remains is a smaller volume carrying the same minerals. Top that up with mineralized water and you’ve added a second dose to water already carrying a full one, and the reading climbs. A Sulawesi tank has to hold its hardness and TDS steady, so top off with plain RO water and save the mineral mix for the volume you actually removed at a water change.

Don’t correct a stocked tank by adding salt to it

The un-ionized share of total ammonia, which is the form that drives toxicity in aquatic animals, rises about tenfold for each single pH unit and roughly twofold for each ten degrees Celsius of warming.⁷ A Sulawesi tank sits at the warm, alkaline end of both. So pushing pH or hardness in an aquarium whose biological filter isn’t fully established is a real risk to the animals. Correct the water outside the tank and bring the correction in slowly through changes.

The routine that keeps this stable is short:

Mix every batch of change water to the same finished pH, GH and TDS reading, and test it before it goes in.
Top off evaporation with plain RO water only, never with the mineralized mix.
Log the tank reading, not the recipe, since the recipe is what you already know and the drift is what you don’t.

Once the tank has held the same readings through several water changes, it’s ready for stock. Tank-bred Sulawesi shrimp then go into water that already matches what they were raised in, not into water you’re still adjusting around them.