my coral is turning brown, why?

[Linxel]

My coral is turning brown and I'm not sure why. Tank's been stable for months, 75 gallons, running a Reef Octopus skimmer. Params are 0 ammonia, 0 nitrite, 5 nitrate, 8 dKH alk, 420 calcium. Lighting is AI Prime 16HD, 10 hours a day. Only change was adding a new clownfish pair last week. They're not bothering the coral, but the color shift started around then. Any ideas?

[bolt9x]

Sounds like it could be light stress or nutrient swings. What's your phosphate level? New fish could've spiked it if you're overfeeding. Also, check if the clownfish are hosting near the coral, they might be stressing it out indirectly. Try reducing light intensity by 10% for a few days, see if it helps.

[aetherix]

Brown usually means zooxanthellae overproduction, often from low light or high nutrients. You said nitrates are 5, but phosphates could be the culprit. Test those. Also, how old are your bulbs? LEDs degrade over time, might not be pushing enough PAR anymore.

[grizzlon]

Brown usually means zooxanthellae overproduction, often from low light or high nutrients. You said nitrates are 5, but phosphates could be the culprit. Test those. Also, how old are your bulbs? LEDs degrade over time, might not be pushing enough PAR anymore.

Yep, second this. My SPS did the same when my phosphates crept up to 0.1. A couple water changes and cutting back on pellets fixed it.

[Lippyton]

Could be the clownfish messing with the flow near the coral. They're chill but territorial. If they're hosting nearby, the coral might not be getting enough flow or light. Try moving the coral to a different spot, see if it bounces back.

[stormers]

What type of coral is it? Some LPS brown out easier than SPS under the same conditions. If it's a torch or hammer, they're more sensitive to changes in flow and light.

[Linxel]

Thanks for the advice, everyone. It's a torch coral, and the clowns are hosting in a nearby anemone. I'll test phosphates tonight and maybe move the torch to a higher flow area. Appreciate the help!

[ravel9]

Torches are finicky. If the clowns are close, they might be stealing food from it too. Try target feeding the torch with mysis or reef roids, see if that helps the color.

[florinix]

Torches are finicky. If the clowns are close, they might be stealing food from it too. Try target feeding the torch with mysis or reef roids, see if that helps the color.

Yeah, and check your magnesium levels. Low mag can mess with calcium uptake, making corals look dull. Aim for 1350-1400 ppm.

[aerolove]

I've had this happen when my tank was too clean. Corals need some nitrates and phosphates to thrive. Maybe ease up on the skimmer if you're running it 24/7. Let the system find a balance.