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I've been struggling to maintain stable calcium levels for my SPS corals. My tank is a 75-gallon mixed reef with Radion XR15s, running at 80% intensity for 10 hours daily. I dose two-part but my Alk stays steady while Ca drops fast. Anyone got tips on balancing this without messing with Mg?

Hey finscape, I feel your pain. My SPS were looking rough until I switched to a calcium reactor. It's a game-changer, keeps everything rock solid. What's your current dosing schedule like? Maybe tweaking the frequency could help.

I've had success with kalkwasser in my ATO. My 120-gallon tank stays at 420 Ca, 8 dKH without much fuss. Just make sure your ATO reservoir is big enough to avoid swings. What's your salinity at? That can throw things off too.

floradon wrote: ↑Sat Apr 26, 2025 4:38 pm I've had success with kalkwasser in my ATO. My 120-gallon tank stays at 420 Ca, 8 dKH without much fuss. Just make sure your ATO reservoir is big enough to avoid swings. What's your salinity at? That can throw things off too.

Yo, kalk is legit but sketchy if your evap rate ain't consistent. I run a doser with Red Sea Foundation B, keeps my 90-gallon on point. Gotta check your Mg tho, it's sneaky important.

My SPS were fading until I bumped my Ca to 450. I dose Brightwell Aquatics daily, 5ml at a time. My tank's a 60-cube with T5s, and I run a refugium. Maybe try smaller, more frequent doses? Big swings mess with the vibe.

gripit wrote: ↑Sat Apr 26, 2025 6:23 pm My SPS were fading until I bumped my Ca to 450. I dose Brightwell Aquatics daily, 5ml at a time. My tank's a 60-cube with T5s, and I run a refugium. Maybe try smaller, more frequent doses? Big swings mess with the vibe.

For real, stability's key. I dose 3x a day with a Neptune DOS, keeps my 180-gallon at 430 Ca. What's your Alk at, finscape? If it's high, your corals might be sucking up Ca faster.

I dunno much about dosing, but my LFS said to test daily for a week to find a pattern. My 40-gallon's Ca was all over until I did that. Now I dose 2ml every 6 hours. Maybe try that?

Thanks for the ideas, everyone. I'll test Mg and maybe switch to kalk in the ATO. My Alk's at 9 dKH, salinity 1.025. Appreciate the help!

finscape wrote: ↑Sat Apr 26, 2025 11:10 pm Thanks for the ideas, everyone. I'll test Mg and maybe switch to kalk in the ATO. My Alk's at 9 dKH, salinity 1.025. Appreciate the help!

No prob! Let us know how it goes. Mg was my missing piece too, turned out it was at 1100. Bumped it to 1350 and everything chilled out.

Yeah, Mg's a sneaky one. I test it monthly now. My tank's been happy since I started dosing it separately. Good luck, finscape!