High Calcium and Magnesium

[diabolical_clownfish]

Hi - I'm a beginner with a 35 gallon tank, setup for about ~6 months, with mostly LPS corals and two clownfish. I've recently been getting into Alkinlity, Calcium, and Magnesium testing and discovered an interesting (?) problem. Here are the facts:

- Using the Instant Ocean Reef Crystals salt, with supposedly (400 ppm Calcium, 13 dKH Alkalinity, and 1440 ppm Magnesium) - ref
- Water change maybe once per month, as my nitrate / phosphate seems to be under control via the Santa Monica Drop algae turf scrubber. I have the air pump on 24h and light at 22 hours; I read that the air is supposed to help balance the pH.
- pH is 8.2 and salinity is 35 ppt (seems stable).
- The tank is consuming about 1 dKH per week - I've discovered the problem when it was dropping down to about 6
- Calcium tested very high, at 550
- Magnesium tested very high at 1500
- I've been slowly dosing the homemade baking soda solution to bring up the alkalinity to 8-9, which has worked so far. The calcium doesn't seem to come down (supposed to be consumed along with alkalinity?).
- Most of the corals and one bubble tip anemone seem to be healthy. I lost one tiny montipora digitata and another meteor shower cyphastrea (bleached) when the alk was very low (6).

I'm wondering:

- Is there a downside to very high calcium and magnesium, beyond the typically recommended range?
- How should I bring them down? Perhaps by switching to a lower content salt, like the regular Instant Ocean?

Thanks!

 

[jeffp1]

I also use Reef Crystals and my parameters are like yours. I am mixing instant ocean with the reef crystals to try to bring calcium and mag. down. It seems to be working.

 

[diabolical_clownfish]

Thank Jeff - that's good to know. I've ordered some regular Instant Ocean, will try the mixing method.

Generally, if my calcium is really high, should I match alk at the upper range? e.g., 10 instead of the usual 8?

 

[blasterman]

This is the classic LPS tank that consumes alk but consumes very little if any calcium. Your tank is not the exception - its the norm. People just get obsessed with two part dosing and won't believe the numbers.

Couple reports here about Reef Crystal's having 500' ish calcium. Doesnt hurt anything, but it can make things complex in a higher consumption SPS tank.

If you aren't consuming calcium you aren't consuming magnesium. Not worth testing. Focus on phosphate and nitrate testing instead.

No need to raise alk, unless...its just easier to keep it at 9-10 because if it drops a couple points you dont stress stuff.

I prefer IO over RC because IO is more consistent. Since you've figured out how easy baking is to use IO would be my suggestion.

 

[vetteguy53081]

Looks like its your mad and Alk that are elevated. Simply do not add any by dosing and add ROI water as needed and see if it comes down as it should. Low coral absorption will also allow it to be elevated.
Assure also by getting a second opinion via water test that you are Not getting false readings.

Temp 77-79
ph 8.1-8.3
salinity 1.025
nitrate < .5
phos < .04
Ammonia < .03
mG 1300
Alk 8-10
CA 440