ideal salinity for coral reef tank

[lavender]

I've been keeping my reef tank at 1.025 salinity, but my Acropora aren't thriving. Anyone have thoughts on whether I should adjust it? My tank's a 75-gallon with T5 lighting, running a protein skimmer, and weekly 10% water changes.

[flintek]

1.025 is solid for most corals, but Acros can be picky. What's your alkalinity sitting at? If it's below 8 dKH, that might be the real issue. Also, how old are your bulbs? T5s lose intensity after about 9 months.

[waves_4]

I've had better luck with Acros at 1.026. It's a tiny bump, but they seem to dig it. My tank's similar to yours, 80 gallons with LED lights, and I dose calcium and magnesium weekly. Maybe give it a shot?

[Avalon]

Salinity is only part of the equation. Have you checked your magnesium levels? Acropora need stable magnesium around 1350 ppm. If that's off, no amount of salinity tweaking will help. Also, what's your flow like? They need strong, random flow to thrive.

[Vynix21]

1.025 is solid for most corals, but Acros can be picky. What's your alkalinity sitting at? If it's below 8 dKH, that might be the real issue. Also, how old are your bulbs? T5s lose intensity after about 9 months.

Yep, alk is huge. I run mine at 8.5 dKH and keep salinity at 1.026. My Acros are growing like weeds. Also, +1 on checking the bulbs. Old T5s can mess with coral health big time.

[lavender]

Thanks for the tips, everyone. My alk is at 7.5 dKH, and the bulbs are about a year old. I'll test magnesium tonight and look into new bulbs. Appreciate the help!

[waves_4]

Thanks for the tips, everyone. My alk is at 7.5 dKH, and the bulbs are about a year old. I'll test magnesium tonight and look into new bulbs. Appreciate the help!

No prob! Let us know how it goes. Bumping alk to 8.5 and swapping bulbs might do the trick. My Acros perked up after similar changes.

[flintek]

Yeah, 7.5 dKH is on the low side for Acros. I'd aim for 8.5 like Vynix said. Also, if you're not already, consider dosing two-part to keep things stable. Big swings in alk can stress them out more than slightly off salinity.

[Avalon]

Stability is key. Once you dial in alk and mag, give it a few weeks before making more changes. Acros take time to adjust. And if you're upgrading bulbs, go for ATI or Giesemann. Cheap ones can give your tank a weird vibe.

[Vynix21]

Totally agree with Avalon. Stability over everything. I've seen tanks crash from too many quick fixes. Slow and steady wins the race with Acros. Also, if you're gonna dose, start small. Overdoing it can sketch things out fast.