Macroalgae melting?

[TriangleReef]

The bottom two photos are from last week. All of the algae’s were doing great and sending out lots of new growth and then over the course of two days I’ve had one of my sea grapes and some of my needle leafed algae’s blanch out and cloud the tank up. This tank has only a surface skimmer and a wave maker, I use natural seawater and a clip on shop light. The tank gets lots of sunlight throughout the day.
If anyone knows what might be causing this please let me know

 

[Dread Pirate Dave]

The bottom two photos are from last week. All of the algae’s were doing great and sending out lots of new growth and then over the course of two days I’ve had one of my sea grapes and some of my needle leafed algae’s blanch out and cloud the tank up. This tank has only a surface skimmer and a wave maker, I use natural seawater and a clip on shop light. The tank gets lots of sunlight throughout the day.
If anyone knows what might be causing this please let me know

The tank looks new. Are you dosing anything like chaetogro?
https://www.brightwellaquatics.com/products/chaeto-gro.php

Your light may not be strong enough too.

 

[Randy Holmes-Farley Verified Community Expert]

Sporulation of the caulerpa may have happened. Folks often call that “going sexual” as it reproduces.

 

[TriangleReef]

The tank looks new. Are you dosing anything like chaetogro?
https://www.brightwellaquatics.com/products/chaeto-gro.php

Your light may not be strong enough too.

didn’t realise Macroalgae would require dosing! What strength light would I need in your opinion?

 

[TriangleReef]

Sporulation of the caulerpa may have happened. Folks often call that “going sexual” as it reproduces.

Would that look like swelling of the grapes (ignore all innuendos) on the caulerpa?

 

[Dread Pirate Dave]

didn’t realise Macroalgae would require dosing! What strength light would I need in your opinion?

I don't grow any macro algae myself but I'd think a 100 watt daylight floodlight would do the trick.

Are there any fish in the tank? I didn't notice any. A lack of fish waste for plant nutrients could also be a problem.

 

[Fish Fan]

I'm wondering if maybe that light is too strong, it seems like it's smoking everything right under it

 

[Dread Pirate Dave]

I'm wondering if maybe that light is too strong, it seems like it's smoking everything right under it

That's possible too. It doesn't look that strong to me but I'm no good at guessing by what my eyes are telling me. lol

Possibly raising the light to give it a larger spread? Some of the macro seems to be in less light.

 

[Fish Fan]

That's possible too. It doesn't look that strong to me but I'm no good at guessing by what my eyes are telling me. lol

Possibly raising the light to give it a larger spread? Some of the macro seems to be in less light.

I think we're all just guessing without some idea of the wattage of the bulb, short of a PAR result

 

[Randy Holmes-Farley Verified Community Expert]

Would that look like swelling of the grapes (ignore all innuendos) on the caulerpa?

I don’t think they swell. The caulerpa releases spores and then goes white and dies back.

 

[Subsea]

I don’t think they swell. The caulerpa releases spores and then goes white and dies back.

OP,
I think your nutrients bottomed out as Caulerpa was growing fast and as a survival technique, it went sexual and disintegrated spreading its spores into the water.

Keep up with N & P and consider dosing trace elements.

Also, you don’t need a stronger light. Keep up with temperature of the tank, if lite by heavy sunlight.

I grow & sell ornamental seaweed to LFS. Less light is preferable to more light.