Grape Caulerpa turn yellow and soften

[BengBear]

Hi,
Bought hand full of 'young and small' Grape Caulerpa and kept them in beta box. They waved gently on 1st day. The next day, realised that half of them turn yellowish from bottom up. Did following:
Kh was somewhere around 5 because of water change. Ramp up to near 7Kh, temperature steady at 29 deg C. Zoa corals were doing well.
Added salifert Iodine. It seems yellowing stopped.
Lighting ok as Zoa corals open up in response. Color of Zoa were ok.
Introduced 2 scarlet hermit

On 3rd day
It seems some 2 small bunches of grape were ok. Zoa corals remain strong.
Other long time inhabitants, scarlet hermits and cleaner (yellow and red) are ok. Of course the fishes are ok.

Question: what caused the grape caulerpa to turn yellow, soften and died?
These were eaten up by 2 scarlet hermit which were introduced 2300hr 2nd day. Is it the iodine or the sorb-4, phoshate remover introduced on evening of day 1.

[Varga]

it went sexual. thats what it does. some say keeping the lights on 24/7 prevents that but I believe that is a debated issue.

[sasquatch]

Heres an online description, at times Ive had it overrun my fuge and be just fine for months, at other times it will be all gone in two days, pruning is hit and miss, lighting is the same all in all cheato to me is still the easiest and most fail safe macro, but the grape just looks so nice when its growing well.

Animal Description:

The Grape Caulerpa is an interesting macroalga that is one of the more popular plants used in home aquariums, and it can be an ideal addition to a refugium or a tank used for similar purposes.

A Grape Caulerpa should be trimmed regularly to prevent it from becoming overgrown. When these plants reach maturity, they may attempt to reproduce sexually. Normally, the Grape Caulerpa will release a great deal of a green substance, and then, over the course of a few days, it will turn white and die. This is not only a nuisance, but it can also harm other organisms living in the same aquarium as the Caulerpa. Again, regular trimming can prevent this. Most Grape Caulerpas use their rhizoids to attach themselves to rocky substrates. They are often found wild in high surf, intertidal, or sub-tidal areas. However, in some areas, Grape Caulerpa has been found at a depth of 66 feet (20 meters). The rhizoids are used only to anchor the plant, not to absorb nutrients. All nutrients are absorbed through the thin walls of the Caulerpa's leaves or manufactured photosynthetically. In captivity, the Grape Caulerpa is considered to be useful in controlling nitrate and phosphate levels, because it absorbs these compounds from the water.

Small bud-like branch tips similar to tiny grapes give the Grape Caulerpa its name. These grow from branches, which grow from whitish or yellow mats of rhizomes. It may grow to heights between 0.5 and 6 inches (1 and 15 centimeters).

Found along coastlines, Grape Caulerpa usually attach themselves to rocks or rocky substrates. This macroalga is one of the more popular plants kept in aquariums.

[Witfull]

sexual Caulerpa of any species will spell danger to a reefer. yank all you can turn up the skimmer and add carbon immediately.

[BengBear]

Hi All,
Beside Grape turning sexual, Do you think it is the water quality differences which may be another cause, as the Kh was somewhere 5 to 6 and calcium near 300 or less?

It is now the fourth day and the remnant Grape Caulerpa, small bunches, are standing strong and green, just like the Zoa corals.

Kh ramped up near 7 Kh, calcium ramped up for 2 to 3 days now. And on the 3rd day, Iodine was ramped up further with Salifert Iodine solution.

Appreciate reviews and comments.

[johnmaloney]

Just to add in, when macro goes sexual, you should really moitor your ph, as it may swing as carbon dioxide is released into the tank.

[BengBear]

ok, there was no water change as nitrate was slowly coming down. It might be due to some macroalgae and cheato in the sump tank being exposed to 12hrs of light nightly for past 1 week.

Just trimmed off some white caulerpa and realised that the slightly white caulerpa become greener.

Any comments???