Here we offer an overview and tips for keeping Acropora and other stoney corals in good condition.

Water flow
Think ehiem 1060 in a 40 gallon tank or more, once these types of coral start growing they will slow water flow greatly as they increase their density. This is where variable pumps like the Tunze streams come into there own as using the controller options you can get the pumps to pulse between 30-100%. This allows output to increase as the stock density increases. Without high levels of water flows these corals will tend to develop infections caused by the inability of the more dense centre's to build up waste this can become a breeding ground for bacteria leading to various disease problems.

Calcium 400-420ppm
Alkalinity 8-9dkh
It is essential to provide these corals with adequate levels of both calcium and alkalinity. A calcium reactor is needed to provide sufficient replacement of alkalinity and calcium. It is worth noting that a tank well stocked with Acropora corals will probably use about 10-15kg of calcium per square metre per year. This is very dependent on levels of lighting and species but is not a bad benchmark if 80% of the tank when viewed from above has coverage of Acropora. You may not start this way but you could be looking at this sort of coverage after a couple of year's growth. Also coralline algae that grows on rocks and glass is included in this usage.

Phosphate
is the scourge of most reef tanks when its not feeding nuisance algae then it is slowing or stopping the growth of hard corals it should be undetectable on Merck or Salifert low range.

Nitrate
again this should be undetectable on Salifert low range test kit.
Consider adding a further export methods for keeping nitrate below 0.0040ppm this helps reduce the over production of zooxanthellae which will happen in a nutrient enriched environment. Either more rock and improved flow or a DSB, Sulphur Filter, Mangrove Refugium all will help to keep nutrients under control.

Lighting
At least 400-800 watts per square meter of surface area We run 6500k lamps for maximum efficiency you may choose 10k or 20k lamps although the output is greatly reduced but as with all things you will see a different adaptation under 10k lighting in comparison to 6500k. In general 20k lamps provide to little illumination for health and vigour although some deeper water species may do well. A 20 k lamp would make a good additional supplementary light to 6500k or 10k

How to keep the Colour
Well if we could answer that we would have retired along time ago. There is no definitive answer to this question only some guidelines that are worth following. The colour of a freshly imported Acropora will seldom stay the same after it has been in the tank for a couple of months although some species are pretty constant. If you have good conditions that meet the criteria mentioned above then there is a good chance that the coral you end up with will look pretty good

Having said that some species remain pretty much the same from the day they were imported. The reasons for this are many and to date there is no exact answer. Some easily controlled reasons for loss of colour or browning.

High nitrates
anything detectable on a standard hobby test kit will cause some form of colour change. Usually browning due to the rapid reproduction in Zooxanthellae.

Elevated trace elements
over dosing with these besides causing algae blooms will again cause a increase in Zooxanthellae production.

Insufficient light
again lighting at below the optimum level will probably cause corals to create additional zooxanthellae to compensate for the loss nutrition. Also lack of output from ageing lamps our experience has shown that 6-9months is optimal with metal halide and 12 months is about the max if you are serious.

Low Alkalinity
some people who keep SPS corals advocate very high KH levels as this can increase colour. In essence aim for a balanced calcium and alkalinity of 450ppm calcium and a KH of 10. This will provide adequate resources of calcium and carbonates for growth.

Inadequate diet
It has been fairly well agreed that the availability of certain pigment primers and amino acids are utilised by SPS corals and will help with colouration. We have seen a number of diets recommended and we feel that with experience you should experiment with what suits your corals and tank. Especially in terms of waste export. We have seen noticeable results from the use of products such as Salifert coral food and Reef solution by ecosystem, both offer a range of amino acids as food sources and vitamins; the corals absorb these. As for more solid foods the best we have seen are the combination blender diets. These cover a broad spectrum of nutritional requirements for a range of marine animals. There is little positive evidence that phyto plankton is utilised by SPS corals many consuming it and then expelling it again, although the additions of phyto will go a long way to increasing the planktonic count of a tank; as it will supply a range of foods to lower life forms that will spawn in the water increasing the available food.

Low Salinity
in days of old hobbyist often recommended running reef tanks at lower than natural seawater levels to economise on salt and in theory reduce the osmotic pressure on the tank inhabitants. The modern reality is that given good filtration and water quality there is no reason to run salinity at less than that of full strength seawater around 10.25/26 sg

Poor growth
All SPS have differing growth rates and some show almost manic growth given optimal conditions others are slow and plodding. A number of factors affect general growth and vigour.

Lack of light
Having outlined the need for plenty of good illumination if a coral finds itself in a position with lower levels of light, growth will stop almost completely. If you own an Acropora and it has shown little growth over a 3-4 month period then it may well be time to move it to a more favourable position.

Poor nutrition
the feeding section has largely covered this but in general coral growth will improve for feeding.

Elevated phosphate levels
are pretty much like lack of light once phosphates are detectable SPS growth will diminish to near zero in many species. It is good advice to run a phosphate remover like salifert phostphate remover .

Over lighting
as much as insufficient light will stunt growth. Over lighting a species that comes from a lower light level, will either cause an adaptation of the coral, but more often or not minimal growth and bleaching.

Lack of stability
such as temperature and pH, keeping theses two aspects of the tank constant is essential for optimal growth. Optimal calcification is often given at a pH of 8.3.

Lack of adequate calcium and carbonate
although most SPS corals will show growth in environments with low calcium it is usually slow. Raising the levels will almost always cause a rapid spurt of growth if all other parameters are good. From our experience it is not until the saturation of calcium reaches 450ppm that rapid growth is experienced. It's interesting to see the rapid change in growth from raising the levels, from say 350 to 450. It is often quite startling as many new growth points spring out from what had been a fairly static growing coral.

Shipping stress
Many corals shutdown for a number of weeks if they have not been shipped well. This can be a touch and go time. Around 6 weeks seems to be usual before new growth nodes are seen.

Too many soft corals
we have not really got a definitive species list but over the years we have seen sps corals make almost no growth in tanks, which are predominately filled with soft corals. Having said that we have seen just the opposite in a number of cases where both co exist and both thrive but it is the exception in our experience. The same can be said for trying to grow soft corals in tanks full of SPS corals.