Tips for keeping Duncan corals

LPS, SPS and all coral chat
TerraCore
Posts: 5
Joined: Sun Mar 19, 2023 7:00 pm

Tips for keeping Duncan corals

Post by TerraCore »

My Duncan corals aren't extending their polyps as much as they used to. I've got them in a 40-gallon tank with moderate flow, 78°F, and 1.025 salinity. Lighting is AI Prime at 60%. Any ideas what's up?
SeaLord2
Posts: 6
Joined: Thu Oct 10, 2024 5:35 pm

Re: Tips for keeping Duncan corals

Post by SeaLord2 »

Duncans can be picky about flow. If it's too strong, they'll stay closed. Try moving them to a lower flow area and see if they perk up. Also, check your alkalinity, they like it stable around 8-9 dKH.
boxreef
Posts: 6
Joined: Sun Oct 13, 2024 5:19 am

Re: Tips for keeping Duncan corals

Post by boxreef »

Mine did the same thing when I first got them. Took a few days to adjust. Maybe they're just settling in?
starlit9
Posts: 5
Joined: Thu Oct 10, 2024 7:23 pm

Re: Tips for keeping Duncan corals

Post by starlit9 »

SeaLord2 wrote: Thu Sep 18, 2025 11:40 pm Duncans can be picky about flow. If it's too strong, they'll stay closed. Try moving them to a lower flow area and see if they perk up. Also, check your alkalinity, they like it stable around 8-9 dKH.
Yep, flow's a big one. Mine threw a fit when I cranked up the wavemaker. Chill flow and they'll thank you.
fluxo
Posts: 6
Joined: Thu Oct 10, 2024 7:35 pm

Re: Tips for keeping Duncan corals

Post by fluxo »

I've had luck feeding mine small bits of mysis shrimp. They're greedy little things once they get going. Maybe try target feeding to encourage them to open up.
Murder
Posts: 9
Joined: Mon Jan 30, 2023 2:31 am

Re: Tips for keeping Duncan corals

Post by Murder »

Duncans are pretty hardy, but they do need stable params. If your alk is swinging, they'll sulk. Test your magnesium too, it should be around 1350 ppm. Also, how old are your bulbs? Older lights can mess with their vibe.
TerraCore
Posts: 5
Joined: Sun Mar 19, 2023 7:00 pm

Re: Tips for keeping Duncan corals

Post by TerraCore »

Thanks for the tips, everyone. I'll try moving them to a lower flow spot and check my alk tonight.
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nightowl7
Posts: 3
Joined: Thu Apr 07, 2022 3:30 pm

Re: Tips for keeping Duncan corals

Post by nightowl7 »

Duncans are chill once you dial it in. Mine love the sandbed, low flow, and a sprinkle of reef roids every now and then. Keep it simple, ya know?
dusoma
Posts: 3
Joined: Thu Oct 10, 2024 5:27 pm

Re: Tips for keeping Duncan corals

Post by dusoma »

Mine didn't open for a week. Then one day, boom, full extension. Sometimes they just need time.
Kodakai
Posts: 5
Joined: Thu Oct 10, 2024 4:54 pm

Re: Tips for keeping Duncan corals

Post by Kodakai »

I've heard some folks say Duncans are like the divas of the coral world. Not sure if that's true, but mine sure are picky about their spot.
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