why are my corals shrinking?

[FinleyK]

My corals aren't growing like they used to. Tank's 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. Lighting's a Kessil A360X, running 8 hours a day. Been doing weekly 10% water changes with Red Sea Coral Pro. Any ideas?

[alynna]

Shrinking corals can be tricky. How old's your tank? Sometimes newer systems take time to stabilize. Also, what's your alkalinity at? I've seen dips cause issues like this. Check your magnesium too, low levels can mess with calcification.

[Vigor7]

Yo, sounds like your setup's solid. Maybe cut the light cycle back a bit? Too much intensity can stress them out. My Zoas did the same till I dialed it down.

[pennor]

Yo, sounds like your setup's solid. Maybe cut the light cycle back a bit? Too much intensity can stress them out. My Zoas did the same till I dialed it down.

I agree. Light stress is a common culprit. Try reducing intensity by 20% for a week, see if they perk up.

[olivine]

Sketchy vibe with the Cleaner Shrimp. Mine kept picking at my corals when food was low. You feeding enough? Maybe toss in some extra mysis, see if they chill out.

[loggins]

What's your temp at? Swings above 80°F can cause shrinkage. Also, how's flow in the tank? Stagnant spots might be an issue. My MP10 fixed similar problems.

[FinleyK]

Thanks for the tips, everyone. Alkalinity's at 8 dKH, magnesium's 1350. Tank's been running for a year. I'll try reducing the light and upping feeding. Temp stays at 78°F, but flow might be weak in one corner.

[alynna]

Thanks for the tips, everyone. Alkalinity's at 8 dKH, magnesium's 1350. Tank's been running for a year. I'll try reducing the light and upping feeding. Temp stays at 78°F, but flow might be weak in one corner.

Those numbers look good. Weak flow could definitely be part of it. Try repositioning your powerhead or adding a small wave maker.

[lazord]

Ever test for phosphates? High levels can stunt growth. API kits sometimes miss low readings, so maybe grab a Hanna checker if you haven't already.

[town_ace]

Just got a new gaming PC, gonna play some Fortnite later. Anyone else into that?