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stable alkalinity for corals
Posted: Mon Jun 30, 2025 3:32 am
by LyraFusion
My tank's alkalinity keeps swinging between 7 and 9 dKH. I'm dosing two-part but can't seem to lock it in. Anyone else dealt with this? Running a 75-gallon mixed reef with T5/LED hybrid lighting, weekly 10% water changes, and a Reef Octopus skimmer.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 3:43 am
by north9
What's your dosing schedule like? I had similar issues until I switched to dosing smaller amounts more frequently. My 120-gallon runs at 8.5 dKH now, dosing every 6 hours via a Neptune Apex. Also, check your magnesium levels—low Mg can mess with stability.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 5:40 am
by microbe
north9 wrote: ↑Mon Jun 30, 2025 3:43 am
What's your dosing schedule like? I had similar issues until I switched to dosing smaller amounts more frequently. My 120-gallon runs at 8.5 dKH now, dosing every 6 hours via a Neptune Apex. Also, check your magnesium levels—low Mg can mess with stability.
Yep, seconding the Mg tip. Mine was at 1200 ppm, and things got way smoother after bumping it to 1350. Using Red Sea Coral Pro salt here, 40-gallon cube.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 7:12 am
by florist
Are you testing at the same time daily? Alkalinity can dip overnight if your corals are growing fast. I test at 8 AM and 8 PM to catch swings. My Acros were bleaching until I caught the pattern. Now I dose extra at lights-out.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 8:11 am
by peaceandpain
Honestly, two-part never cut it for me. Switched to a calcium reactor last year, and my alk's been rock-solid at 8.3 dKH. Yeah, it's pricey, but no more daily dosing headaches. 90-gallon SPS-dominated tank, CaribSea substrate.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 9:36 am
by flintech
peaceandpain wrote: ↑Mon Jun 30, 2025 8:11 am
Honestly, two-part never cut it for me. Switched to a calcium reactor last year, and my alk's been rock-solid at 8.3 dKH. Yeah, it's pricey, but no more daily dosing headaches. 90-gallon SPS-dominated tank, CaribSea substrate.
How's the pH with your reactor? I've been eyeing one but worried about CO2 buildup. Running a 60-gallon with Zoas and LPS, dosing manually for now.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 10:21 am
by brinyveg
Dunno if this helps, but my alk stabilized after I stopped chasing numbers. Let it sit at 8 for a week, only adjusted if it dropped below 7.5. Weirdly, my corals looked happier. 30-gallon nano, weekly 5% changes, no skimmer.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 11:33 am
by LyraFusion
Thanks for the tips, everyone. Gonna test Mg and maybe tweak my dosing schedule. Appreciate the real-world advice!
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 12:21 pm
by darwin
Stability's key, but don't stress too much. Corals adapt. My 50-gallon's alk bounces between 7.5 and 8.5, and everything's thriving. Just keep changes gradual. You got this.
Re: stable alkalinity for corals
Posted: Mon Jun 30, 2025 12:59 pm
by trigade
What salt mix are you using? Some brands have inconsistent alk levels straight out of the bag. I switched to Fritz RPM after my old mix gave me wild swings. 100-gallon mixed reef, monthly 15% changes.