Why is my tank not using calcium?

[Lps_lover12]

My tank is about 15 months old, 100 gallons and about 20 corals mostly lps and a few softies. I dose about 10ml of alk everyday to keep it stable but in the whole time it’s been setup I’ve probably only had to dose about 50ml of calcium and that was only for a week straight and never had to dose magnesium, I haven’t done a water change in a while because my nutrients are stable at around 5.5 nitrates and phosphates around 0.02 and I read that if your calcium isn’t getting used then neither are trace elements so I didn’t worry about that. Does anyone know why it’s not using any calcium or magnesium? Ph is 8.2 during the day and about 7.9 at night

 

[Propane]

Are your corals growing?

 

[Lps_lover12]

Are your corals growing?

Some of them, my one octospawn that was one head is now 4, a frogspawn has grown from 2 to 4 all hammers are growing lots of new heads (small but growing) my Duncan’s and mushrooms are growing like crazy and torch, lobo are growing as well

 

[vetteguy53081]

My tank is about 15 months old, 100 gallons and about 20 corals mostly lps and a few softies. I dose about 10ml of alk everyday to keep it stable but in the whole time it’s been setup I’ve probably only had to dose about 50ml of calcium and that was only for a week straight and never had to dose magnesium, I haven’t done a water change in a while because my nutrients are stable at around 5.5 nitrates and phosphates around 0.02 and I read that if your calcium isn’t getting used then neither are trace elements so I didn’t worry about that. Does anyone know why it’s not using any calcium or magnesium? Ph is 8.2 during the day and about 7.9 at night

Softies and LPS will not absorb CA at the rate SPS and other stony coral will and consumption will be lower. How is your alk usage?

 

[Propane]

If you trust your test kit and your corals are growing I wouldn’t be concerned. Depending on the salt you use you might be putting enough back in to compensate with water changes.

 

[Lps_lover12]

Softies and LPS will not absorb CA at the rate SPS and other stony coral will and consumption will be lower. How is your alk usage?

About 10ml a day to keep it stable

 

[Lps_lover12]

If you trust your test kit and your corals are growing I wouldn’t be concerned. Depending on the salt you use you might be putting enough back in to compensate with water changes.

The weird part is I haven’t done a water change in a few months

 

[Lavey29]

About 10ml a day to keep it stable

This is a very small amount for 100g tank. As others stated LPS and softs don't uptake much calcium. Once coraline starts and you add more corals you will see consumption. I dose 35ml daily in a 65g tank.

 

[Northern Flicker]

Water changes only supplement, they don’t replenish.

It kind of sounds like your coral just aren’t using a ton. I wouldn’t worry too much, it would be more suspect if you had intense skeletal growth on dozens of coral but no changes to water chemistry.

 

[Lps_lover12]

This is a very small amount for 100g tank. As others stated LPS and softs don't uptake much calcium. Once coraline starts and you add more corals you will see consumption. I dose 35ml daily in a 65g tank.

I have coralline growing but slowly. Looking for some new corals just not sure which ones to get

 

[Lps_lover12]

Water changes only supplement, they don’t replenish.

It kind of sounds like your coral just aren’t using a ton. I wouldn’t worry too much, it would be more suspect if you had intense skeletal growth on dozens of coral but no changes to water chemistry.

Good point, thank you

 

[vetteguy53081]

About 10ml a day to keep it stable

How are you testing? 10ml not a whole lot if coral is indeed absorbing it

 

[Lps_lover12]

How are you testing? 10ml not a whole lot if coral is indeed absorbing it

Trident and Hannah. Both are within 0.10 of each other and using a NYOS kit every few week to check they are all around the same

 

[vetteguy53081]

Trident and Hannah. Both are within 0.10 of each other and using a NYOS kit every few week to check they are all around the same

Great. Its not unusual to have low consumption and even high , the reason we test and dose accordingly.
What I would do if you are not doing already is to chart the alk and calcium usage the next 30 days and look for consistency and a trend. If all over the chart would be concern but if consistent would be your norm.

 

[Lps_lover12]

Great. Its not unusual to have low consumption and even high , the reason we test and dose accordingly.
What I would do if you are not doing already is to chart the alk and calcium usage the next 30 days and look for consistency and a trend. If all over the chart would be concern but if consistent would be your norm.

So just see how much I have to dose each day to keep it stable? Should I just test the same time each day and see how close they are and if I had to dose any?

 

[vetteguy53081]

So just see how much I have to dose each day to keep it stable? Should I just test the same time each day and see how close they are and if I had to dose any?

Yes. You will then know your dosing needs and usage. By charting you will develop a pattern for dosing and usage by coral. Thereafter if there is a drop or increase, it will alert you to your tank specs changing and determine cause

 

[Lps_lover12]

Yes. You will then know your dosing needs and usage. By charting you will develop a pattern for dosing and usage by coral. Thereafter if there is a drop or increase, it will alert you to your tank specs changing and determine cause

Thank you, I’ll do that for sure and I greatly appreciate the help

 

[Randy Holmes-Farley Verified Community Expert]

I’m not sure what alk product you are dosing, but with alk demand that low (less than 0.2 dKH per day), it is very hard to detect the calcium demand (about 1 ppm daily) except very long term, and water changes may supply all that is needed.