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My corals have been fading over the past few weeks. Tank is a 40-gallon with two Clownfish, a Cleaner Shrimp, and some Zoanthids. Parameters are stable, 0 ammonia, 0 nitrite, 5 nitrate, 8.2 pH, 1.025 salinity. Running a Kessil A160 light for 8 hours a day. Any ideas what's going on?

Could be a lighting issue. The Kessil A160 is decent, but how old is the bulb? Also, what's your phosphate level? High phosphates can mess with color. I'd check that and maybe bump up the light intensity slightly if it's been a while since you replaced it.

I agree with brooklynn. Lighting is often the culprit. Another thing to consider is your feeding routine. Are you dosing any amino acids or coral food? Sometimes they just need a little extra nutrition to keep their vibrancy.

Yep, lighting and nutrients are key. Also, how often are you doing water changes? If it's been more than a month, you might wanna cut it back to every two weeks. Old water can get sketchy even if the params look good.

Thanks for the suggestions. The bulb is about a year old, and phosphates are at 0.03. I'll try increasing the light intensity and see if that helps. I do weekly 10% water changes, but I'll double-check my routine.

Might wanna look into your magnesium levels too. Low mag can cause color loss, especially in Zoanthids. Aim for around 1350 ppm if you're not already there.

I had the same issue last year. Turned out my tank was too clean. Weird vibe, but some corals actually need a bit of nitrate to thrive. Maybe dial back the skimmer if you're running one.

brooklynn wrote: ↑Mon Apr 28, 2025 9:14 am Could be a lighting issue. The Kessil A160 is decent, but how old is the bulb? Also, what's your phosphate level? High phosphates can mess with color. I'd check that and maybe bump up the light intensity slightly if it's been a while since you replaced it.

Yeah, and if the bulb's old, the spectrum might've shifted. Corals can be picky about that.

I'm new to this, but my LFS told me to check my alkalinity. Said it should be between 8 and 12 dKH. Maybe yours is off?

FreshMind wrote: ↑Mon Apr 28, 2025 6:54 pm I'm new to this, but my LFS told me to check my alkalinity. Said it should be between 8 and 12 dKH. Maybe yours is off?

Good point. Alkalinity swings can stress corals out big time. If it's bouncing around, that could explain the color loss.