Caulerpa

Mention the word ‘algae’ to a marine aquarist and the aquarist’s face might turn white, before he or she spins round to look at their aquarium and ask, in a panicky voice, ‘Where?’

We are all aware of that concern: nuisance algae! The stuff that covers everything in long thin strands of green or covers with a thin sheet of dark red or black looking film. Nuisance algae can be combated or avoided in the first place. But this isn’t about nuisance algae.

This is about nice algae for the aquarium! In the marine world there are a lot of types of algae that could come under the word ‘nice.’ They are decorative and sort after. Aquarists who use live rock may have been fortunate to see some grow.

Of course there is one algae that is essential, and this is the single celled type called zooxanthellae, or symbiotic algae, which dwells in the flesh of corals.

The algae here is Caulerpa sp. This is green, though the shade of green can vary, and generally grows longish leaves (sometimes up to 12″) which have various ‘patterns.’ The algae spreads by putting out runners, from the top of which the leaves appear. Underneath are holdfasts, which look a little like roots. The roots are simply anchors, however, as the caulerpa feeds through the leaves. This macro algae is very useful to the marine aquarist for decorative and/or filtration purposes.

A great deal could be written but all that will be done is a general description of the main types and what they could be used for.

The first and probably best known is Caulerpa prolifera. The leaves are plain and have straight edges which taper to a point. The leaves are normally flat. Growth is fairly speedy.

Two more attractive types are Caulerpa mexicana and Caulerpa seratuloides. They both have leaves that look a little like bird feathers, with individual sections sprouting from the stalk sideways on both sides from bottom to tip. These types could show rapid growth.

A different appearance from the previous types is Caulerpa racemosa. It is often called grape caulerpa because of the appearance: the leaves are bunches of small grape-like growths attached to the stalks. This type is more slow growing and more difficult to cultivate successfully.

What can be done with caulerpa? For decorative purposes it would of course be in the display aquarium, where it can look very attractive. However, the aquarist must be sure it doesn’t outgrow its welcome as some can spread rapidly. I had some Caulerpa mexicana in a previous aquarium and it was certainly attractive, though I had to harvest it regularly to maintain control.

The other area that caulerpa is often found is in a sump. Aquarists grow it there so that it can act as a filter. As it is an algae, it uses the same nutrients that nuisance algae does, that is nitrate and phosphate. In doing so it robs any potential nuisance algae of food. Even if hobby test kits indicate zero (undetectable) for nitrate and phosphate, it could well be that there is a low presence. Planting a piece of caulerpa and watching to see if it grows is possibly an indicator. Obviously, algae in a display aquarium will also reduce nutrients.

As with all plants caulerpa needs light. Fluorescent tubes such as T5’s or metal halide bulbs should be fine, so growth in a display aquarium should not be a problem as far as this is concerned.

Caulerpa grown in a sump can be lit a little differently. A fluorescent light with reflector will suffice, the light is usually quite close to the seawater surface. There may be an advantage in using a tube that has a K (Kelvin) value that is lower than normal for a display aquarium, such as 6500K. Or a white marine type can be used, around 10000K. In addition there are two ways of timing the ‘light on’ period. First is to leave the light on all the time without any dark period, which doesn’t seem to have any detrimental effect on the caulerpa, and the second is to have the light on period when the display aquarium is in the light off period. The second option could assist with pH stability - pH could fall a little when the display is in the dark period, but with the caulerpa lit this is counteracted.

When planting in a display aquarium, try the type of choice and see if there is any success. If not, try another type. In the sump, it could be a good idea to plant more than one type and see which ’takes’ first.

Caulerpa should be harvested from time to time, always leaving plenty to continue growth. As the plant uses nutrients, removing the caulerpa in a controlled manner also exports nutrients.

The aquarist may find that the caulerpa in the display aquarium is disappearing. Have a look at algae loving fish such as surgeons and rabbit fish - they could be fat and very happy!

Important Note: Caulerpa in the aquarium is fine, decorative and useful. However, when harvesting, or simply removing caulerpa of any type it must not be thrown away into the sea. Caulerpa is invasive and can and is causing problems.

In some areas caulerpa is banned because of problems. Please check the position in your area before obtaining caulerpa.

For some information here is a link:

http://www.sccat.net/#the-caulerpa-information-center-1e86c5

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Tags: Algae, Aquarium Filtration, Aquarium Lighting, caulerpa, deep-sand-bed, refugium

Remember To Harvest The Algae In The Algae Bed

In a [tag-tec]saltwater aquarium[/tag-tec] it is preferential to have both nitrates and phosphate as well as various other nutrients at the lowest possible level you can achieve.

Growing algae in the sump or in the refugium is an excellent way to remove nutrients from the water column, good examples which are nitrate and phosphate.

Once established the algae in the sump/refugium can reduce the nutrients to a very low level.

So why would you want to harvest this algae when you have spent all this time trying to make it grow?

What happens is that the algae in the algae bed, dependant upon the species being grown will grow in line with the water movement which passes through the bed. Over time the algae will form quite a dense ‘forest’ of algae – so much to the extent that a lot of the light provided will not be able to penetrate through to the lower levels.

Now you may think that this is ok as the leaves at the top will be able to grow using the light provided, however what happens is that the leaves and/or plants lower down in the sump/refugium will actually die.

When most algae die the nutrients which have been processed are released back into the water column, therefore all those nutrients which have been removed are suddenly released back into the aquarium water.

There are times when the entire algae bed dies and all the nutrients are instantly released back into the aquarium. When this happens your system will be loaded with nutrients and various problems can occur.

Therefore when you grow macro algae in your [tag-ice]sump[/tag-ice] or [tag-tec]refugium[/tag-tec] it is imperative that from time to time you harvest it.

Basically harvesting the macro algae means thinning it out.

To harvest the algae simply remove some of the algae, but do not remove any of the roots as this will prevent it from growing back. I personally use an old pair of scissors and give the algae bed a haircut!

When you harvest the algae what you are doing is removing a lot of nutrient laden plant life from the water and exposing what remains to the light provided to them. The macro algae will then start to re-grow removing even from nutrients from the water column.

Over time the algae bed will re-grow and eventually it will be time to harvest it again.

It has been noted by numerous aquarists that harvesting the algae bed the number of algae bed crashes experienced has significantly reduced.

When you remove the algae do not be tempted to feed it to the aquarium inhabitants as you are effectively feeding nutrients back into the water. Either throw it away or give it away to another aquarist who is just starting a new algae bed.

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Tags: Algae, algae-bed, caulerpa, nitrate, phosphate