LPS vs SPS Corals: Which Suits Your Tank?

Both groups are stony corals that build calcium carbonate skeletons, and that is roughly where the resemblance ends. LPS vs SPS corals is really a question about how much stability your system can hold, not about which one looks better under blue light. Large polyp stony corals carry thick, fleshy tissue that buffers them through a bad week. Small polyp stony corals stretch a thin veneer of tissue over a dense skeleton and notice everything that moves. In a Chicago home with forced-air heat, a full work schedule and the occasional week away, that difference decides which group is realistic.

What LPS vs SPS corals actually means at the tissue level

The LPS group covers corals whose individual polyps are large enough to see clearly: hammer, torch and frogspawn corals, Acanthastrea, Favia, Duncan, Blastomussa, Trachyphyllia, candy cane and the plate corals. Their tissue can inflate to several times the volume of the skeleton underneath. That mass is not decoration: it stores energy, shades the skeleton, and gives the animal something to lose slowly rather than all at once, which is why an unhappy LPS colony gives you days of warning.

SPS corals work the opposite way. Acropora, Montipora, Stylophora, Seriatopora and Pocillopora build dense skeletons and cover them with a tissue layer often less than a millimeter thick, studded with polyps a few millimeters across. Color lives in pigments held in that thin layer, so an SPS colony reports a change in light or chemistry within days while an LPS colony is still deciding. Growth is faster, structure is finer, and there is almost no reserve to fall back on.

Plenty of corals sit awkwardly between the two labels, and the categories are a hobby convention rather than a taxonomic rule. Goniopora and Alveopora look like LPS and behave like neither. Pavona and encrusting Montipora are grouped with SPS but tolerate conditions closer to the LPS end. Our overview of the main types of live coral sorts the common aquarium genera into groups and explains what each one asks for.

Stability is the line that separates LPS vs SPS corals

Alkalinity is where the split shows first. Small polyp stony corals pull calcium and carbonate from the water quickly and react badly to the level moving, so a swing of more than about half a dKH in a day can burn growth tips and start necrosis that runs down a branch overnight. Most reef tanks sit between 8 and 11 dKH, and SPS keepers pick a number in that band and hold it within a few tenths. LPS colonies shrug off drift that would strip an Acropora.

Nutrients and temperature follow the same pattern. SPS want nitrate and phosphate low but genuinely present, since a tank stripped to zero pales them out, while LPS tolerate and often benefit from a richer water column. Temperature matters more here than in most parts of the country. A furnace cycling hard in January, a July stretch without air conditioning and a week away from home are all ordinary Chicago events, and each one moves a tank that has no automation behind it.

That leads to a practical division. An SPS-dominant reef effectively requires two-part dosing or a calcium reactor, a reliable auto top-off, a controller watching temperature, and testing on a schedule you keep rather than one you intend. An LPS reef can run for years on regular water changes, a decent skimmer and attentive feeding. Neither system is more legitimate than the other, but only one of them forgives the week you spent traveling for work.

Flow and placement ask different things of each group

SPS corals need strong, turbulent, randomized flow, and the reason is mechanical rather than aesthetic. Thin tissue relies on water movement to carry away mucus and detritus and to deliver dissolved nutrients across the surface. Two opposing powerheads or a gyre pump produce the chaotic pattern these corals grew up in. What they do not want is a laminar jet aimed at one face, which strips tissue on the windward side and leaves a bare patch.

LPS corals want moderate, indirect flow and enough of it to keep detritus from settling in their folds. Too much movement stops a hammer or torch from inflating, and a sharp stream can tear fleshy tissue against its own skeleton. Plate corals belong on the sand bed where they can move themselves. Most other LPS do best on the lower or middle rockwork, positioned so the current reaches them after it has bounced off glass or rock rather than head-on.

Spacing is the part people underestimate. Euphyllia species extend sweeper tentacles several inches after dark and will burn anything they touch, so four to six inches of clear space around a hammer or torch is a minimum. Acanthastrea and Favia sweep too, over shorter distances. SPS colonies do their damage by growing, shading a neighbor out over a season or fusing into a branch you cannot separate later. Leave gaps that look excessive on day one.

Light demand is a range, not a ranking

Published PAR figures give useful boundaries as long as you treat them as bands rather than targets. Most LPS colonies color up and grow somewhere around 75 to 150 PAR, and many will sulk above that. SPS generally want 200 and upward, with Acropora at the top of the range and encrusting Montipora comfortable well below it. The number that matters is the one at the coral, not the one on the fixture box.

How a coral was grown matters more than any figure. A frag raised under moderate light on a vendor's lower rack will bleach if you place it at the top of your rockwork on day one, regardless of whether that spot suits the species. Start every new coral low, watch it for two weeks, and move it up in short steps. Spectrum shapes color response as much as intensity does, and our guide to reef light spectrum explains how blue-heavy settings drive pigment in both groups.

Borrow or rent a PAR meter if you can, because guessing costs more than measuring. Map the tank once, mark two or three zones on the glass with tape, then place corals by zone instead of by eye. A mixed reef laid out this way keeps LPS in the shaded lower third and SPS across the top, which also happens to match what each group wants from flow.

Feeding, growth and the cost of a failure

Feeding separates the two groups more sharply than most guides admit. LPS corals take meaty food directly: mysis, chopped seafood and small pellets dropped onto an open polyp two or three times a week, which accelerates growth and helps a stressed colony recover. SPS corals capture much smaller particles and get most of their energy from light and dissolved nutrients, so you feed the tank and the fish rather than the coral itself. A skimmer set too aggressively on an SPS system quietly removes the food supply.

The asymmetry that should decide your choice is what failure looks like. An SPS colony that meets a serious alkalinity swing can lose all its tissue in under a day, and rapid tissue necrosis leaves a bare white skeleton by morning with nothing to save. An LPS colony under the same insult recedes over days or weeks, which usually gives you time to test, correct and cut healthy frags from what remains. That difference is worth more than any comparison of growth rates.

• Choose LPS if the tank is under a year old, or if parameters still move noticeably between tests

• Choose LPS if you travel, work long hours, or nobody is home midweek to catch a failed heater

• Move toward SPS once alkalinity holds within a few tenths of a dKH from one test to the next

• Move toward SPS if dosing, an auto top-off, a controller and a real testing routine are already in place

• Run a mixed reef by keeping LPS low and shaded, SPS high and windswept, and the alkalinity target steady

Most home reefs we service around Chicago and the suburbs end up mixed, and that works well provided you accept the compromise honestly. Set the parameters for the SPS, since they are the group with no tolerance, then accommodate the LPS through placement rather than by loosening the chemistry. Adding an Acropora to a tank tuned for hammers is the version that fails, because the LPS never complains loudly enough to warn you in time.

Key takeaways

• LPS vs SPS corals is a stability question first: thick tissue buffers mistakes, thin tissue does not.

• SPS need alkalinity held within a few tenths of a dKH; LPS tolerate normal week-to-week drift.

• SPS want strong turbulent flow up high; LPS want moderate indirect flow lower down, with room for sweepers.

• Light bands matter less than acclimation, so start every coral low and move it up in steps.

• An SPS failure can be total within a day, while an LPS failure usually leaves you something to save.

Frequently asked questions

Can LPS and SPS corals live in the same tank?

Yes, and most mature reefs are mixed. Set your chemistry to suit the SPS, since they have the narrower tolerance, then place LPS lower and in gentler flow. Keep several inches between fleshy LPS and anything else, because sweeper tentacles reach further after dark than they appear to during the day.

How long should a reef run before adding SPS?

Watch the numbers rather than the calendar. Once alkalinity, salinity and temperature hold steady across several weeks of routine testing, the tank is ready regardless of its age. In practice that is usually past six months, and starting with a hardy Montipora rather than an Acropora makes the first attempt more informative.

Which group is more likely to survive a power outage?

LPS corals generally handle a few hours without flow better, since their tissue holds reserves and they tolerate a temperature drift. SPS colonies suffer quickly once flow stops and detritus settles on their tissue. A battery backup on one circulation pump protects both groups and costs less than replacing a single colony.

Work with Marine Concepts Inc

If you are unsure which group your system can hold, bring your last few test results and talk it through before you buy. Our Wheeling, IL aquarium and coral shop stocks frags, salt, test kits and dosing equipment for same-day local pickup, and we would rather send you home with a hardy LPS colony than an Acropora your tank is not ready to keep alive.