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My Acropora started bleaching last week, and I'm not sure why. Water params are good, 0 ammonia, 0 nitrite, 5 nitrate, 8.2 pH, 1.025 salinity. Running two AI Primes at 70% for 8 hours, tank's a 40-gallon breeder with a Nero 3 for flow. No recent changes except adding a couple of new fish. Any ideas?

Bleaching can happen for a few reasons. How's your alkalinity and calcium? Acropora are super sensitive to swings. Also, what's your temp stability like? Even small fluctuations can stress them out. I'd check those first before messing with anything else.

vortex wrote: ↑Wed Apr 16, 2025 4:19 am Bleaching can happen for a few reasons. How's your alkalinity and calcium? Acropora are super sensitive to swings. Also, what's your temp stability like? Even small fluctuations can stress them out. I'd check those first before messing with anything else.

Yep, vortex nailed it. Alk swings are a killer. What's your dosing routine like? If you're not consistent, that could be the culprit. Also, how old are your bulbs? Older LEDs can shift spectrum and mess with corals.

Dude, same thing happened to me last month. Turned out my heater was sketchy, temps were all over the place. Got a new one and things chilled out. Maybe check your heater? Also, those new fish could be stressing the coral if they're nipping or something.

I'd second checking alkalinity and calcium. Acropora need stable parameters. Also, what's your phosphate level? High phosphates can contribute to bleaching. If everything else checks out, it might just be the new fish causing stress. Give it some time and see if things improve.

Have you tested for stray voltage? Sometimes a faulty pump or heater can leak current into the water, stressing corals. I've seen it cause bleaching before. A simple multimeter check could rule that out. Also, how's your flow pattern? Dead spots can lead to issues.

Misty wrote: ↑Wed Apr 16, 2025 9:05 am Have you tested for stray voltage? Sometimes a faulty pump or heater can leak current into the water, stressing corals. I've seen it cause bleaching before. A simple multimeter check could rule that out. Also, how's your flow pattern? Dead spots can lead to issues.

Thanks for the suggestions, everyone. I'll test for stray voltage and double-check my alk and calcium. My heater's a year old, so maybe it's time for a replacement. Appreciate the help!

Let us know what you find. Stray voltage is a sneaky one, easy to overlook. If it's not that, maybe try reducing light intensity for a bit. Sometimes corals just need a break from high light, especially if they're already stressed.

Yeah, dialing back the lights could help. I had to do that with my Acropora once, and it bounced back after a couple weeks. Just don't go too dark, or you'll have other problems. Gotta find that sweet spot.

If you're replacing the heater, go for a titanium one. They're more reliable and less likely to fail. Also, consider adding a backup heater if you don't have one already. Temp stability is huge for Acropora.