Can SPS and LPS corals share one tank?

Yes, with zones and spacing. SPS need high light, strong flow and steady alkalinity with very little swing, while most LPS want medium light and medium flow plus feeding. Place the LPS down-current of the SPS so its sweeper tentacles cannot reach them at night. The real difficulty is not coexistence but satisfying the demand for rock-steady parameters and the demand for feeding with the same water, since feeding raises nutrients and SPS are the most sensitive group to nutrient swings.

Two mechanisms. The physical one is sweeper tentacles: LPS such as hammer, torch and bubble corals extend tentacles several times their body length at night that burn and dissolve the tissue of a neighbour. The chemical one is allelopathy, since most soft corals release terpenes into the water that suppress nearby corals, and the concentration rises as the tank gets smaller, the flow weaker and the carbon older. That makes spacing and fresh carbon the two lifelines of a mixed reef.

What KH, calcium and magnesium should a reef tank hold?

The usual targets are alkalinity 7 to 9 dKH, calcium 400 to 450 mg/L and magnesium 1250 to 1350 mg/L, with specific gravity between 1.023 and 1.026 at 25 °C. The three interact, and while magnesium sits below range neither calcium nor alkalinity can be held high, which is the most common reason dosing appears to do nothing. Stony corals, SPS especially, consume all three quickly enough to need daily dosing or a calcium reactor, while a soft coral tank usually stays in range on regular water changes alone.

Will an anemone kill my corals?

It can, and it is one of the most common losses in a reef tank. An anemone moves on its own and leaves a trail of burned tissue behind it, and once it settles beside a coral that patch of coral is usually gone. Anemones are also regularly drawn into powerheads, which destroys the anemone and fouls the whole tank at the same time. If you want one, either give it a tank of its own or settle it in a fixed area well clear of corals and pump intakes.

Do soft corals really poison stony corals?

In a small tank with weak flow and no carbon, yes. The compounds released by leathers, finger corals and zoanthids inhibit stony coral growth and in the worst case cause localised bleaching. The three countermeasures are more flow, fresh carbon changed regularly and placing soft corals downstream of the stony corals. The larger the tank and the more frequent the water changes, the smaller the effect.

G-03 · Marine

Coral atlas

Compatibility works differently for corals than for fish. Fish are limited by temperament, corals by physical distance and chemical warfare. The atlas therefore gives aggression its own field: species with sweeper tentacles, most LPS, extend tentacles several times their own length at night and burn whatever they reach, while species that release toxins, most soft corals, can suppress stony corals in a small tank with weak flow and no carbon. The three water parameters of alkalinity, calcium and magnesium are the raw material stony corals use to build their skeletons and are far less critical for soft corals, which is why dedicated soft coral and stony coral tanks are set up separately.

Coral losses in a mixed reef almost always come down to placement and spacing rather than water quality, because sweeper tentacles can burn a neighbour overnight.

Units: temperature in °C, hardness in German degrees (dGH / dKH), marine salinity as specific gravity at 25 °C, volume in litres. These are the values recorded for the species and do not follow the site unit switcher.

Coral type

Light

Flow

Aggression

26 of 26 entries

Coral atlas
Name	Type	Light	PAR	Flow	Aggression	Feeding	Level
Staghorn coralAcropora spp.鹿角珊瑚	Stony coral · SPS	Very high light	300–450	High flow	No aggression	No feeding needed	Advanced
Montipora coralMontipora spp.蔷薇珊瑚	Stony coral · SPS	High light	200–300	High flow	No aggression	No feeding needed	Moderate
Cauliflower coralPocillopora damicornis鹿角杯形珊瑚	Stony coral · SPS	High light	200–300	High flow	No aggression	No feeding needed	Moderate
Bird’s nest coralSeriatopora hystrix鸟巢珊瑚	Stony coral · SPS	High light	200–300	High flow	No aggression	No feeding needed	Moderate
Smooth cauliflower coralStylophora pistillata柱状珊瑚	Stony coral · SPS	High light	200–300	High flow	No aggression	No feeding needed	Moderate
Torch coralEuphyllia glabrescens火炬珊瑚	Stony coral · LPS	Medium light	100–150	Medium flow	Sweeper tentacles	Optional feeding	Beginner
Frogspawn coralFimbriaphyllia divisa蛙卵珊瑚	Stony coral · LPS	Medium light	100–150	Medium flow	Sweeper tentacles	Optional feeding	Moderate
Hammer coralFimbriaphyllia ancora锤头珊瑚（榔头）	Stony coral · LPS	Medium light	100–150	Medium flow	Sweeper tentacles	Optional feeding	Beginner
Candy cane coralCaulastraea furcata炮仗花珊瑚	Stony coral · LPS	Low light	50–80	Medium flow	Sweeper tentacles	Optional feeding	Beginner
Moon coralFavites abdita蜂巢脑珊瑚	Stony coral · LPS	Low light	50–80	Medium flow	Sweeper tentacles	Optional feeding	Beginner
Open brain coralTrachyphyllia geoffroyi开放脑珊瑚	Stony coral · LPS	Low light	50–80	Low flow	Sweeper tentacles	Feeding required	Moderate
Duncan coralDuncanopsammia axifuga邓肯珊瑚	Stony coral · LPS	Medium light	100–150	Medium flow	Sweeper tentacles	Optional feeding	Beginner
Pineapple coralBlastomussa wellsi爆仗花珊瑚	Stony coral · LPS	Low light	50–80	Low flow	No aggression	Feeding required	Moderate
Toadstool leather coralSarcophyton glaucum皮革珊瑚	Soft coral	Medium light	100–160	Medium flow	Chemical toxins	No feeding needed	Beginner
Finger leather coralSinularia flexibilis手指皮革	Soft coral	Medium light	100–160	Medium flow	Chemical toxins	No feeding needed	Beginner
Devil’s hand leather coralLobophytum pauciflorum魔鬼手指	Soft coral	Medium light	100–160	Medium flow	Chemical toxins	No feeding needed	Beginner
Button polypsZoanthus spp.纽扣珊瑚	Soft coral	Medium light	80–150	Medium flow	Chemical toxins	Optional feeding	Beginner
Giant palythoaPalythoa grandis大纽扣	Soft coral	Medium light	80–150	Medium flow	Chemical toxins	Optional feeding	Beginner
Yuma mushroom coralRicordea yuma香菇珊瑚	Soft coral	Low light	50–80	Low flow	Chemical toxins	Optional feeding	Beginner
Mushroom coralDiscosoma spp.蘑菇珊瑚	Soft coral	Low light	30–60	Low flow	Chemical toxins	No feeding needed	Beginner
Pulsing xeniaXenia umbellata白银珊瑚	Soft coral	Low light	50–80	Medium flow	No aggression	No feeding needed	Beginner
Green star polypsBriareum violaceum草皮珊瑚	Soft coral	Medium light	80–150	Medium flow	No aggression	No feeding needed	Beginner
Bubble tip anemoneEntacmaea quadricolor奶嘴海葵	Anemone	High light	160–250	Medium flow	Sweeper tentacles	Optional feeding	Beginner
Magnificent sea anemoneHeteractis magnifica公主海葵	Anemone	Very high light	300–450	High flow	Sweeper tentacles	Optional feeding	Advanced
Crocea clamTridacna crocea五爪贝	Clam	Very high light	300–450	High flow	No aggression	Optional feeding	Moderate
Maxima clamTridacna maxima长砗磲	Clam	Very high light	300–400	Medium flow	No aggression	Optional feeding	Moderate

How to use it

Step 1Map the tank into zones by light and flowDivide the tank into high light and strong flow, medium for both, and low light with gentle flow, then place corals by their tier instead of buying first and hunting for a spot afterwards.
Step 2Leave spacing for aggressionA coral marked for sweeper tentacles needs a gap of at least one adult diameter from its neighbour, and a tank with chemical aggressors should run carbon continuously.
Step 3Check alkalinity, calcium and magnesiumStony corals need all three, soft corals mainly alkalinity and salinity. The three interact, and dosing calcium without magnesium stops calcium from being laid down.
Step 4Confirm the feeding requirementA coral marked as needing target feeding will slowly recede without it, while one marked as needing none will foul the water if fed. Feeding is the easiest thing in a reef tank to overdo.

Frequently asked questions

Can SPS and LPS corals share one tank?: Yes, with zones and spacing. SPS need high light, strong flow and steady alkalinity with very little swing, while most LPS want medium light and medium flow plus feeding. Place the LPS down-current of the SPS so its sweeper tentacles cannot reach them at night. The real difficulty is not coexistence but satisfying the demand for rock-steady parameters and the demand for feeding with the same water, since feeding raises nutrients and SPS are the most sensitive group to nutrient swings.
Why do corals fight?: Two mechanisms. The physical one is sweeper tentacles: LPS such as hammer, torch and bubble corals extend tentacles several times their body length at night that burn and dissolve the tissue of a neighbour. The chemical one is allelopathy, since most soft corals release terpenes into the water that suppress nearby corals, and the concentration rises as the tank gets smaller, the flow weaker and the carbon older. That makes spacing and fresh carbon the two lifelines of a mixed reef.
What KH, calcium and magnesium should a reef tank hold?: The usual targets are alkalinity 7 to 9 dKH, calcium 400 to 450 mg/L and magnesium 1250 to 1350 mg/L, with specific gravity between 1.023 and 1.026 at 25 °C. The three interact, and while magnesium sits below range neither calcium nor alkalinity can be held high, which is the most common reason dosing appears to do nothing. Stony corals, SPS especially, consume all three quickly enough to need daily dosing or a calcium reactor, while a soft coral tank usually stays in range on regular water changes alone.
Will an anemone kill my corals?: It can, and it is one of the most common losses in a reef tank. An anemone moves on its own and leaves a trail of burned tissue behind it, and once it settles beside a coral that patch of coral is usually gone. Anemones are also regularly drawn into powerheads, which destroys the anemone and fouls the whole tank at the same time. If you want one, either give it a tank of its own or settle it in a fixed area well clear of corals and pump intakes.
Do soft corals really poison stony corals?: In a small tank with weak flow and no carbon, yes. The compounds released by leathers, finger corals and zoanthids inhibit stony coral growth and in the worst case cause localised bleaching. The three countermeasures are more flow, fresh carbon changed regularly and placing soft corals downstream of the stony corals. The larger the tank and the more frequent the water changes, the smaller the effect.