Ideal phosphate levels for corals

[lumino]

My corals aren't growing as fast as they used to. I've heard phosphate levels might be the issue. What's the ideal range for them? My tank's a 40-gallon with mixed LPS and SPS, running a protein skimmer and T5 lighting.

[sweetflake]

You're right to check phosphates. For most corals, you wanna keep it between 0.03 and 0.1 ppm. Higher than that, and you'll get algae blooms, lower might starve them. What's your current reading? Also, what salt mix are you using?

[robson]

You're right to check phosphates. For most corals, you wanna keep it between 0.03 and 0.1 ppm. Higher than that, and you'll get algae blooms, lower might starve them. What's your current reading? Also, what salt mix are you using?

Spot on. I'd add that SPS are more sensitive, so aim for the lower end if you've got Acros or Montis. My Red Sea test kit shows 0.05 ppm, and my Acros are thriving. How often do you test?

[timbrs]

Yep, gotta keep those phosphates in check. I run a 75-gallon with a refugium, and my chaeto keeps it steady at 0.07 ppm. If you're not running one, maybe cut back on feeding or up your water changes. What's your current maintenance routine?

[lumino]

Thanks for the advice, everyone. I'm using Instant Ocean salt and testing weekly with a Hanna checker. Last reading was 0.15 ppm, so I'll try reducing feedings and see if that helps.

[carina]

0.15 ppm is definitely on the high side. I'd also check your RO/DI water—sometimes the source has phosphates. My tank was a mess until I realized my filter cartridges were shot. What's your filtration setup like?

[silvana]

Agreed on the RO/DI check. I had a similar issue last year. Switched to a BRS 4-stage system, and my phosphates dropped to 0.02 ppm within a month. Also, how old are your test kits? They can go bad over time.

[finfisher]

If you're still struggling, consider a phosphate remover like GFO. I run it in a media bag in my sump, and it keeps things stable. Just don't overdo it—you don't wanna crash your levels overnight.

[prairiel7]

GFO's a solid choice, but it can be pricey. I've had luck with phosguard in a pinch. Also, what's your lighting schedule? Too much light can exacerbate phosphate issues, especially if you're already high.

[flora]

I'm new to this, but my LFS told me to aim for 0.05 ppm. Is that too low for soft corals? I've got a 20-gallon with zoas and mushrooms, no skimmer yet.