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What's the best salinity range for SPS corals? I've been running my tank at 1.025, but my Acropora aren't thriving. Parameters are stable, 0 ammonia, 0 nitrite, 8 dKH, 450 calcium. Lighting is AI Hydra 32, 75-gallon tank with a Reef Octopus skimmer.

1.025 is generally fine, but some SPS prefer 1.026. How's your magnesium? If it's below 1300, that could be the issue. Also, check your alk swings, they're sensitive to that. What's your water change routine?

riverra wrote: ↑Fri Aug 22, 2025 10:04 am 1.025 is generally fine, but some SPS prefer 1.026. How's your magnesium? If it's below 1300, that could be the issue. Also, check your alk swings, they're sensitive to that. What's your water change routine?

Magnesium is at 1350, and I do 10% weekly changes with Red Sea Coral Pro. Alk stays between 8-9 dKH. Maybe I should bump salinity to 1.026 slowly?

I've had better luck at 1.026 with my SPS. Just raise it over a week or two to avoid shocking them. What's your flow like? High flow helps them too.

My Acros hated 1.025, but perked up at 1.026. Also, how old's your tank? Newer tanks can be sketchy for SPS. Mine took 6 months to settle in.

Salinity isn't the only factor. What's your phosphate level? SPS can struggle if it's above 0.05. I run mine at 1.026 with zero issues, but I also dose amino acids.

I'm new to SPS. Why does salinity matter so much? My LFS said 1.025 is fine, but my montis are browning out.

cutler wrote: ↑Fri Aug 22, 2025 4:16 pm I'm new to SPS. Why does salinity matter so much? My LFS said 1.025 is fine, but my montis are browning out.

Salinity affects osmotic pressure. Too low, and they can't absorb nutrients right. Montis are tougher, so if they're struggling, check your nitrates too. Aim for under 5 ppm.

Thanks for the advice, everyone. I'll bump salinity to 1.026 slowly and monitor. Flow is two MP40s at 70%, and phosphates are at 0.03. Tank's been up for 8 months.

Sounds like you're on the right track. Just don't rush the salinity change. SPS can be drama queens if things shift too fast.