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How often do y'all change water in a mixed reef tank? I've got a 50-gallon with Zoanthids, Acros, and a couple LPS. Running a protein skimmer and dosing two-part. Currently doing 10% weekly but wondering if I can cut it back.

Stick with weekly changes if you're dosing. Corals like stability, and small, frequent changes keep parameters steady. I run a 75-gallon SPS dominant tank and do 15% weekly with Red Sea Coral Pro salt. Skimmer helps, but nothing replaces fresh saltwater.

I've had success with biweekly 20% changes in my 40-gallon mixed reef. Key is testing alk, calcium, and mag religiously. If those stay stable, you can stretch it. But if your Acros start looking sketchy, bump it back up.

My tank's smaller, 30 gallons, but I do 5% weekly. Seems to work? Corals are alive at least. Got a couple softies and a Duncan that's growing slow but steady.

dusky9 wrote: ↑Mon Aug 18, 2025 1:33 am I've had success with biweekly 20% changes in my 40-gallon mixed reef. Key is testing alk, calcium, and mag religiously. If those stay stable, you can stretch it. But if your Acros start looking sketchy, bump it back up.

Agree on testing, but I'd caution against biweekly unless you're running a refugium. Nutrient creep is real, especially with LPS. Weekly 10% is safer long-term.

Y'all are making me feel lazy. I do monthly 25% on my 60-gallon and everything's chill. Then again, I've got a massive chaeto fuge and a GFO reactor. Maybe that's cutting me some slack.

Thanks for the input, everyone. Gonna stick with weekly for now but might test the waters with a longer interval if my params stay solid.

kubson wrote: ↑Mon Aug 18, 2025 3:51 am Y'all are making me feel lazy. I do monthly 25% on my 60-gallon and everything's chill. Then again, I've got a massive chaeto fuge and a GFO reactor. Maybe that's cutting me some slack.

That's the dream, but most folks don't have your filtration setup. For the average reefer, weekly is the way to go. Less room for error.

True, but it's also about knowing your tank. Some systems just run cleaner. My buddy's 100-gallon barely needs water changes thanks to a killer CUC and light bioload. Meanwhile, my Acros throw a fit if I'm a day late.

Exactly. There's no one-size-fits-all. Monitor your corals' response. If your Zoas stay closed or Acros pale, that's your cue to up the frequency. Better safe than sorry with SPS.