Calcium low despite balanced 2part dosing( ESV)

[Beefyreefy]

Hello, I'm struggling with low calcium readings. It all started when I did a tank upgrade to a larger system. I added new coral and water volume. I also ended up purchasing a new doser. So I made some changes to say the least. My display tank is 125 gallons, and with sump volume (minus rock volume) I think I have about 165 gallons total water volume. My salinity hovers around 1.026. So, currently my calcium reads at 320ppm and my alkalinity is between 10-11dkh. I am currently dosing 49ml of each component of ESV bionic 2part per day, does that seem appropriate? I attached a tank pic to give you an idea off my stocking level. I did try bringing up the calcium manually by dosing over top of what is being added by the doser but it seemed very difficult to move where I wanted it. Is it possible that I'm over dosing 2 part and driving the calcium down? I did notice I have white little spots on my glass which I thought were tube worms forming but now I'm thinking maybe calcium precipitation? My corals are mostly doing ok but I have noticed slower growth in my hard corals and some new zoa frags fizzled away if you can believe it. I need a plan of attack to sort this out and get things back on track so any direction you can give me is very much appreciated.

 

[Randy Holmes-Farley]

You cannot correct low calcium with equal parts dosing of any amount, because alkalinity will go through the roof.

Your calcium is so low I'd be sure to double check with a different kit before raising it, but to do so, use just the calcium part or just calcium chloride to raise it.

Maybe try your kit on some new salt water.

 

[ScottR]

I’d also double check that your refractometer is correctly calibrated.

 

[rvlcf]

Also make sure your magnesium levels are good. Low mag can make raising calcium difficult.

 

[Randy Holmes-Farley]

Also make sure your magnesium levels are good. Low mag can make raising calcium difficult.

That is true in the general sense, but it is not a way one can arrive at low calcium and high alk if all he is dosing is equal parts of B-ionic. Precipitation of calcium carbonate, the reduction of which is what magnesium does, necessarily takes out about 2.8 dKH of alkalinity for each 20 ppm of calcium. For calcium to fall, alkalinity would need to either fall a huge amount, or be added back some other way.

 

[Beefyreefy]

You cannot correct low calcium with equal parts dosing of any amount, because alkalinity will go through the roof.

Your calcium is so low I'd be sure to double check with a different kit before raising it, but to do so, use just the calcium part or just calcium chloride to raise it.

Maybe try your kit on some new salt water.

Thanks for the replies. When I tried to raise the calcium manually I did it by just adding the calcium part, not both parts, sorry if that was unclear. When I did this , I recall it took more calcium than I thought to get it borderline acceptable. Ultimately, I got here through lack of testing. I assumed that once I got it closer to acceptable ranges that dosing equal parts from there after would keep both calcium and alkalinity within range. I stopped testing and now I'm at low calcium again and high alk. On my previous system, I never had any difficulty keeping things in range with adding equal parts, which is why I'm now baffled. I will check my test kit on my stored ASW I have mixed up. Once I do that Ill report back. I guess if that's reading low its a test kit problem. Oh, I meant to mention that my refractometer is calibrated as I use calibration fluid frequently.

 

[Randy Holmes-Farley]

Are you using dosing pumps that may not be delivering the volume you think?

Are you adding alkalinity any other way? Tap Water?

Water changes with a high alk low calcium mix (lie normal IO) may get you into this situation.

 

[Beefyreefy]

Are you using dosing pumps that may not be delivering the volume you think?

Are you adding alkalinity any other way? Tap Water?

Water changes with a high alk low calcium mix (lie normal IO) may get you into this situation.

Just to be safe, I recalibrated my dosing pump the other day, it wasn't too far off from the previous calibration. I am not adding alkalinity any other way and all my water is RODI that I prepare myself. So, now that you mention it, I use instant ocean. and I do more frequent, small water changes. My thinking being was that smaller more frequent changes would have less effect on the tanks stability. Now I wonder if that's the problem since you brought it up.

 

[Beefyreefy]

I tested some stored Instant Ocean ASW I kee on hand (1.026) and I’m getting the same reading, 320 ppm. Being that it’s the same as my main system water reading, I have deducted that my test kit is inaccurate but reproducible or my saltmix has low calcium. I do frequent small batch water changes so either are possible. I’m going to order a different test kit. In the meantime since I have some wiggle room for raising calciUm either way, I’m going to start dosing cautiously, because I’d rather be upper normal than low.

 

[Randy Holmes-Farley]

I tested some stored Instant Ocean ASW I kee on hand (1.026) and I’m getting the same reading, 320 ppm. Being that it’s the same as my main system water reading, I have deducted that my test kit is inaccurate but reproducible or my saltmix has low calcium. I do frequent small batch water changes so either are possible. I’m going to order a different test kit. In the meantime since I have some wiggle room for raising calciUm either way, I’m going to start dosing cautiously, because I’d rather be upper normal than low.

That sounds like a fine plan. Double
check your salinity measurement too.