A fine refugium?

Katze · Oct 18, 2025

Hello everyone!

This is my first ever proper refugium, it's not the best but does what it must.
I'm concerned about pruning the algae, I want to have some to decrease my nitrates and remove some to not shade and take up space. Because as far as I know macroalgae use most nutrients during growth.
Furthermore I'm doubting it's overall efficiency, is there anything to upgrade other than size?

Current NO3: 35-40ppm (desired: 10-20ppm)
Algae species: Caulerpa Prolifera and Gracilaria
Corals in the fuge: Clavularia sp.

Subsea · Oct 19, 2025

Not sure what your question is? If you desire is to lower nitrates using your refugium, then increase light intensity or duration. Also, when seaweed gets thick, prune & export.

Katze · Oct 19, 2025

Subsea said:
Not sure what your question is? If you desire is to lower nitrates using your refugium, then increase light intensity or duration. Also, when seaweed gets thick, prune & export.

Basically you've answered the 2 questions. But then in case of caulerpa how dense is too dense? Like can the density shown in the picture be consedered as "dense"?

CedarReef · Oct 19, 2025

Probably best to prune consistently rather than waiting for it to get too dense. I learned this when I removed too much chaeto from my fuge and started to notice green hair algae come back in the display before the fuge grew backZ.

Subsea · Oct 19, 2025

Katze said:
Basically you've answered the 2 questions. But then in case of caulerpa how dense is too dense? Like can the density shown in the picture be consedered as "dense"?

If mat is so dense that light is shaded at bottom of mat then seaweed is too dense. In your top picture, your red gracilaria is shaded by the Caulerpa

toothybugs · Oct 29, 2025

Grab a handful and rip it out til you get good light penetration through everything. Don't worry about hurting the macro or anything. It'll be fine.

areefer01 · Oct 29, 2025

Subsea said:
Not sure what your question is? If you desire is to lower nitrates using your refugium, then increase light intensity or duration. Also, when seaweed gets thick, prune & export.

Makes a great, natural, food for herbivores :) At least that is what I do with mine.

Subsea · Oct 29, 2025

Katze said:
Basically you've answered the 2 questions. But then in case of caulerpa how dense is too dense? Like can the density shown in the picture be consedered as "dense"?

Seaweed in refugiums is too dense when light can not penetrate. In the case of chaetomorphy, some turn it over periodically.

I suggest not letting it get thick. Exudates from mature seaweed add DOC, so not pruning and exporting will contribute to buildup of DOC, which can be detrimental.

Subsea · Oct 29, 2025

areefer01 said:
Makes a great, natural, food for herbivores :) At least that is what I do with mine.

Nice butterflies! Do they not eat the seaweed?

Cheezeits · Oct 29, 2025

Do you run any CUC in the refugium?

areefer01 · Oct 29, 2025

Subsea said:
Nice butterflies! Do they not eat the seaweed?

Both the Copperband and the Milletseed race to the algae to see who gets the Aiptasia first. The Milletseed usually wins but the Copperband doesn't care because it also gets the worms. As to eating the actual seaweed the Milletseed does. Mostly the roots or runners that the Sea Grapes have. It does not eat the larger pieces.

Interesting that you noted that as I also have a Pyramid and Zoster who pick at the larger pieces. My Scopas, Gold Lined Rabbitfish, and more recently new, baby, Blue Tang eat the majority of it. The Gold Line eats it like a spaghetti noodle which is always fun to watch.

I do not harvest it but maybe every other month as it is a slow grower for me. May be lighting, may be flow, not sure. I can usually pull a nice handful out though and in it are worms, pods, Aiptasia, and Strombus Grazer (Strombus maculatus) snails. I've read elsewhere that it can be consumed by humans and used in some sushi recipes but I'm not 100% sure I have the right sea grape.

TY by the way on the comment. Unfortunately, my Copperband does not eat prepared food and only forages. I've had it for 5 years now. As a result I do not keep any other animal that competes with its food / foraging type. The Milletseed is from Biota and a hidden gem. Love it.

Katze · Oct 29, 2025

Cheezeits said:
Do you run any CUC in the refugium?

Nope, honestly I have no CUC at all

Subsea · Oct 29, 2025

areefer01 said:
Both the Copperband and the Milletseed race to the algae to see who gets the Aiptasia first. The Milletseed usually wins but the Copperband doesn't care because it also gets the worms. As to eating the actual seaweed the Milletseed does. Mostly the roots or runners that the Sea Grapes have. It does not eat the larger pieces.

Interesting that you noted that as I also have a Pyramid and Zoster who pick at the larger pieces. My Scopas, Gold Lined Rabbitfish, and more recently new, baby, Blue Tang eat the majority of it. The Gold Line eats it like a spaghetti noodle which is always fun to watch.

I do not harvest it but maybe every other month as it is a slow grower for me. May be lighting, may be flow, not sure. I can usually pull a nice handful out though and in it are worms, pods, Aiptasia, and Strombus Grazer (Strombus maculatus) snails. I've read elsewhere that it can be consumed by humans and used in some sushi recipes but I'm not 100% sure I have the right sea grape.

TY by the way on the comment. Unfortunately, my Copperband does not eat prepared food and only forages. I've had it for 5 years now. As a result I do not keep any other animal that competes with its food / foraging type. The Milletseed is from Biota and a hidden gem. Love it.

I have eaten & enjoyed Grape Calurpa (both C lentillifera & racemosa) & Botacladia. When I make ceviche, I serve three dishes: protein marinade, vegetable marinade and fresh seaweed rinsed in tap water.

I will soon expand on this 55G seaweed tank with no fish and a peppermint shrimp as the apex predator.

Caulerpa lentillifera (Sea Grapes) is recognized for its culinary appeal and can be purchased from IndoPacific SeaFarm.

areefer01 · Oct 29, 2025

Subsea said:
I have eaten & enjoyed Grape Calurpa (both C lentillifera & racemosa) & Botacladia. When I make ceviche, I serve three dishes: protein marinade, vegetable marinade and fresh seaweed rinsed in tap water.

I will soon expand on this 55G seaweed tank with no fish and a peppermint shrimp as the apex predator.

Caulerpa lentillifera (Sea Grapes) is recognized for its culinary appeal and can be purchased from IndoPacific SeaFarm.

Thank you for the information. Appreciate it.

With regards to IPSF that was my source. I am a long time customer (as it relates to our hobby) of theirs and enjoy talking to Mr. Heslinga. Great to see another hobbyist mention them.

Subsea · Oct 31, 2025

areefer01 said:
Thank you for the information. Appreciate it.

With regards to IPSF that was my source. I am a long time customer (as it relates to our hobby) of theirs and enjoy talking to Mr. Heslinga. Great to see another hobbyist mention them.

Yes to IPSF. Gerald Heslingar is a true environmental steward. He passed on an opportunity for pHd at Harvard and partnered with Walt Smith to develop coral growout systems on Paula, IndoPacific.

Staghorn · Oct 31, 2025

With that Caulerpa it’s a good practice to keep it trimmed. If nutrients drop to low it could go sexual and melt down. I’ve had it happen before. And by trimming regularly you should have more stable nutrient readings instead of waiting until it’s super dense and then removing a huge chunk that will affect the rate of consumption. Keep in mind also that if your trying to export the nutrients, by feeding it to your fish you will be adding nutrients back in.