Who Gives A Fish Forums

My Acropora colonies have been growing really slow lately. I've got them under Radion XR15s, running the AB+ schedule, and my params are stable, 8.1 dKH, 420 calcium, 1350 magnesium. Any ideas why they're not taking off?

Yo, slow growth can be a vibe killer. What's your nitrate and phosphate at? If they're too low, your Acros might be starving. Mine took off when I bumped nitrates to 5 ppm and phosphates to 0.05.

oceana9 wrote: ↑Thu Jul 31, 2025 1:20 am Yo, slow growth can be a vibe killer. What's your nitrate and phosphate at? If they're too low, your Acros might be starving. Mine took off when I bumped nitrates to 5 ppm and phosphates to 0.05.

That's solid advice. Also, check your flow. Acros need random, turbulent flow to thrive. I use two MP40s on reef crest mode.

How old is your tank? Acros can be picky in newer setups. Mine didn't start growing well until my tank was over a year old. Stability is key.

I'd double-check your lighting intensity too. Even with the AB+ schedule, if your PAR is too low or high, growth can stall. I aim for 300–350 PAR at the Acro level.

Bro, have you tried feeding them? Reef Roids or Aminos can give 'em a boost. My Acros love it when I spot feed 'em twice a week.

What's your alk consumption like? If it's not steady, that could stress 'em out. I dose to keep alk within 0.5 dKH of my target.

I've heard Acros can slow down if there's too much competition from soft corals. Do you have any leathers or zoas nearby?

Mine did the same thing until I switched salts. Some brands have trace elements dialed in better for SPS. Now I use Red Sea Blue Bucket.

Thanks for all the suggestions, everyone. I'll test nitrates and phosphates tonight and adjust my flow. Appreciate the help!