In Your Experience, What Has Been the Optimal Levels of Alk/Calc/Mg for best Coral Health/Growth/Color?

[PeterC99]

Know everyone says don’t chase numbers but there are many experienced, successful Reefers out there with amazing aquariums that control their parameters very closely.

With aquarium controllers/testers/dosers, you can dial in numbers pretty close to where you want them. That said, what has been your optimum levels for Alk/Calc/Mg to get healthy, fast growing, and colorful corals?

 

[blaxsun]

I think salinity, temperature, pH, nitrates and phosphates also play a role, but I’ve been trying to maintain 8.5 dKH alkalinity, 450ppm calcium and 1450 magnesium.

 

[PeterC99]

I think salinity, temperature, pH, nitrates and phosphates also play a role, but I’ve been trying to maintain 8.5 dKH alkalinity, 450ppm calcium and 1450 magnesium.

My numbers are very similar except Mg (1300). What are the advantages of the higher Mg and do you dose to keep it that high?

 

[blaxsun]

My numbers are very similar except Mg (1300). What are the advantages of the higher Mg and do you dose to keep it that high?

I’m not entirely sure if there’s any benefit (at least that I’ve seen in the short term) - I just read a BRS article where they’d upped their recommended magnesium level to 1400-1450ppm and figured I’d give it a try.

I do dose a very (tiny) amount to keep it that high, along with a small amount of alkalinity (as most of my tank is soft and LPS, I don’t seem to need to really dose calcium on any mind of regular basis).

 

[Dkmoo]

Alk/CA/Mg only impacts calcification and pH. i think once you are in the recommended ranges for these three, other factors play more important role in terms of health/growth/color

the "perfect target" depends on your own tank's live stock as well as your other parameters and it's all interconnected.

Alk - 8 - 11. Need to be "compatible" with your pH, and nutrient levels, and coral type instead of a perfect fixed number. I keep mine at 9.5 b/c i feed heavy and my CO2 levels, even with scrubber, keeps pH at 8.2, and have a mixed reef thats leaning more and more SPS. If you can maintain pH or have low nutrient levels, or have mostly softie/LPS, then you can stay on the lower end of that range.

CA - 450 - 500. I keep mine at 475 - depends on the type of coral. more "bony" need higher (and higher alk) to aid in calcification. which also in turn need nutrient to be up to prevent burnt tips, and pH to be high (8.1 - 8.3).

Mg - enough to maintain the Alk/CA levels without triggering significant abiotic precipitation (which you'll see both physically on the eye test, and also seeing abnormal daily Alk/CA consumptions that you don't expect with the level of coral stocking). I keep mine at 1300, which keeps my daily alk/ca locked in at 1.4 dkh and 10 ppm daily, respectively.

Color - this has less to do with Alk/Mg/CA, and a lot more to do with nutrient, trace elements, lightning intensity and spectrum. Trace elements you can dose but make sure you at least test them periodically to keep them safe range. lighting is a whole other loaded issue that's really coral dependent.

nutrient - it's hard to say what no3/po4 levels you test in the water is "optimum" b/c it's more about the quantity and quality of what's already consumed, not what's left over in the water. in my tank, i can feed very little, or i can feed very much, but my no3 rarely goes outside of the 0.5 - 1.5 ppm range b/c of the mature tank. Po4 stays at 0.02 - 0.04. I think as long as your tests registers a little bit it's fine. More important is what you feed. I feed AB+, phyto, and cyclops daily, and target feed reefroid/coral frenzy every other, plus fish pee/poop from a slightly overstocked tank.

As you can see, the "sweet spot" is going to be different for every tank. FWIW i listed where i kept mine but more importantly i tried to explain why its kept that that level. Your mileage with my levels may differ.