Seawater Parameter Guidelines

Over and over the importance of seawater quality is emphasized. Seawater quality is the number one requirement for the marine aquarium, be this fish only, coral only or mixed reef. Most corals demand light for health and growth, nevertheless seawater quality is still the number one need.

Guidelines are useful for those who are not experienced in the marine hobby, including those who are setting up an aquarium for the first time as they can help towards purchasing the correct equipment such as pumps. They are also useful for those who feel their aquarium is not as it should be, perhaps fish are not as colourful as expected and corals slow to extend and show polyps. There are several reasons why this could be so but the first place to examine is the seawater.

Even if the seawater was at the correct parameters when first used, as soon as it enters the aquarium where there are life forms it begins to deteriorate. This needs to be counteracted by routine seawater changes of the correct amount and at the correct intervals.

As far as the guidelines are concerned, this is just what they are – guidelines not absolutes. The requirement is quality and stability. The guidelines give a starting point and it is up to the aquarist to carry out tests and know the trends of his/her aquarium. The use of a notebook to jot down the results of various tests is recommended, it takes very little time. The notes will indicate the need for supplementation for example, and at what period and amount. Another example is that notes will indicate the effectiveness of routine seawater changing – is nitrate increasing, stable, or perhaps decreasing? Should the amount of seawater changed be increased etc? Once the aquarist has gained experience then the guidelines can be amended if necessary, but always with caution.

Experienced aquarists could run their aquariums at levels clearly different from the guidelines. This could be for various reasons, such as a low SG (specific gravity) to combat certain fish problems. When any particular action is contemplated, always consider the potential impact it could have on other livestock types in the aquarium before proceeding. Research of livestock requirements is always worthwhile.

General guidelines are given for fish only and reef aquariums.

Temperature: Fish only and reef, between 75 and 80degF. As temperature increases oxygen decreases. It could be best to choose a ‘middle’ temperature of 77degF. Some experienced aquarists use a temperature a little over 80degF as this increases the metabolism of the entire aquarium population – again, caution is required.

SG (Specific Gravity): Fish Only, often from 1.020 to 1.022 though it can be higher (and should be if corals are present). There is some suggestion that certain unwanted parasites that afflict fish fare less well at a lower SG.

                                      Reef: normally 1.024 to 1.026.

pH (Potential of Hydrogen). Fish Only and Reef: between 8.0 and 8.4. A pH of 8.3 is often quoted as the ideal reading, and this is generally so, but other readings are acceptable with stability.

Alkalinity: Fish Only, seldom measured unless pH is a serious problem.

                    Reef, between 8 and 12 dKH.

Ammonia: Fish Only and Reef, nil.

Nitrite: Fish Only and Reef, nil.

Nitrate: Fish Only, below 30ppm but always as low as possible.

                Reef: below 10ppm but always as low as possible.

Phosphate: Fish Only, seldom measured unless algae is a serious problem.

                      Reef, undetectable.

Calcium: Fish Only, seldom measured.

                 Reef, Soft Corals – around 375/400ppm. Hard corals – around 450ppm or a little higher. Calcium also assists other life forms such as snails.

Routine Seawater Changes: Fish Only and Reef, 10% of the net gallonage of the aquarium (including sump if there is one) carried out weekly. Even if parameters remain healthy it is recommended that seawater changes continue, though this could be at a reduced level if applied with caution. Remember that seawater changes ‘freshen’ the aquarium and replace trace elements at least partially.

Seawater Movement: Fish Only, around 10 times the net gallonage of the aquarium (excluding any sump).

                                          Reef, Soft Corals – the same as fish only. Hard Corals, around 20 (or a little more) times the net gallonage of the aquarium (excluding any sump).

The guidelines given do not include items such as Iodine, Strontium and Magnesium which mainly apply to reef systems, particularly those stocked with hard corals. With some of these there is argument over how beneficial they could be. For basic purposes such inclusions generally confuse matters.

If the aquarist maintains basically high quality seawater and applies other necessities correctly, for example lighting and seawater movement the aquarium display should be beautiful. Additional considerations, if any, arise as experience grows and the trends and needs of the aquarium become known.

Trimming A Branching Soft Coral

If the marine environment is of high quality then the occupants should do well. This includes the growth of corals which of course is good. However, this in itself can demand attention from the aquarist.

Some soft branching corals can show very significant growth.This could interfere with seawater flow and light availability – other corals could suffer because of it. A large branch over a smallish coral, throwing it into shade, could mean problems for that coral if the aquarist let things be.

So what can be done? It’s a little worrying when the question of cutting a coral arises and the thought ‘What if?’ comes to mind. The fact is that provided the environment is good corals repond well to trimming. The trimming shouldn’t be too severe of course and thought needs to be given to where and how. The where is easy, it’s the offending branch. The how is also easy, just some care is required.

All that is required in the way of equipment is a pair of quite long and definitely sharp scissors and a bowl to put the cut off coral in. A sharp knife of good length could also be used but scissors tend to permit more accuracy generally.

It’s not time for cutting just yet. First, the cut point should be made where the coral will not be left looking out of balance, that is, it should still look normal when the branch is removed. Usually the cut is made near to the main stem and a very small distance away from it.

Once the cut point has been decided and before the coral shrinks because of interference from the aquarist, the size of the cut off branch should be noted. Is there anywhere in the aquarium that it could be relocated? If there is then it can be securely placed between rocks. If not, then the plastic bowl will hold the piece until it can be transported to the dealers (speak to them first) or passed on to another aquarist. Before being transported in a plastic bag the cut off coral can be placed in seawater in the bowl and the bowl floated in the aquarium to maintain temperature.

The time has come for the cut to be made. Before approaching the coral the aquarist should note the angle the scissors will need to be at. Hands into the aquarium and with the scissors placed as required a single cut right across the base of the the branch should be made – do not open and shut the scissors as would be done when cutting a length of cloth, what is needed is a straight neat cut without any hacking. The branch should come away completely. Sometimes the branch is still fixed to the stem by a shred of coral – cut this also in one movement. The cut branch should never be pulled off by shearing any attachment by force.

The coral will of course react, quite understandably really! It will shrink and go into ‘sulk’ mode. It could also eject some milky substance into the seawater, this is a result of deflation and usually not a concern. The coral will remain closed up for a day or so but will inflate again. The coral should be watched for any sign of rot around the cutting site, this is unlikely if the job has been neatly done. If any rot does occur then it should be removed with about 1/4″ of the cut into healthy coral. For cuts of this type a very sharp knife is generally best.

The photo at the head of this text shows a coral two days after being trimmed. In the photo below the branch on the left of the coral is re-growth from a similar trimming operation which occurred about five months earlier.

Generally speaking corals have a high capacity to re-grow. The re-growth is likely to be different from the original, and where one branch has been removed for example two could re-grow, each of a smaller diameter or just one again. Corals can be trimmed time and again and provided the trimming is not too severe there will usually not be a problem.

Trimming corals has the advantage that additional corals are being produced for use by the aquarist, other aquarists or for the dealer. This is good for the hobby and the reefs. An aquarist who designs a reef carefully could fully populate it over time by using additional corals, although this is not so good an option from the point of view of captive reef variety.

Maintaining an established reef is simple overall - provide a high quality environment, properly populate and take necessary actions following observation, such as the one described here.