Calcium consumption higher than Alkalinity consumption

[Steve2020]

Over the past few months my calcium consumption has increased while KH staying constant. My SPS growth has taken off also during this period. I dose BRS 2 part but a month ago I switched from using the BRS maintenance Magnesium to Tropic Marine part C. Prior to this increase in calcium consumption my test have been very stable at KH=9.0, Cal=445-450 and Mag at 1540. Mag has always been on the higher side. Dosing amounts were 72ml/day for KH and Cal and 12ml BRS Mag prior to this calcium consumption I am seeing. Now after switching to TM part C, KH is still 72ml/day and TM part C is 142ml/day. So, about a month prior to switching to TM part C I was seeing an increase in consumption of Calcium to the point my weekly testing would see a 15-20ppm weekly drop from the normal 450ppm to 430-435ppm so I would add the calculated amount of liquid calcium to bring it back up to 450ppm. Today my readings are KH=9.0, Cal=425 & 430ppm ( 2 test done ) and Mag=1540. I understand TM part C has nothing to do with this increase because I started to see the consumption increase prior to the change.
I was always under the impression that you should always dose BRS 2 part Alk & Cal in equal parts which I have always done. In the past 2yrs my tank has been up and running I occasionally had to make some small corrections in Cal like maybe 100ml additions but the past few months it's been large corrections in the range of 500ml+ per week.
Is this normal to see this Calcium consumption increase compared to Alk when SPS all of a sudden start taking off? We are talking some fast growing frags doubling in size per month.

 

[jsker]

Good question

 

[Randy Holmes-Farley]

Assuming I am reading this long story correctly on a bumpy plane while the Super Bowl is on, lol, and assuming it is not test error or dosing volume error (a common explanation for unusual things) then it means there is another source of alk.

Calcium cannot ever be consumed without consuming the proportional amount of alk.

Dosing nitrate or falling nitrate will add alk.

Water changes can also mess with relative demand.

 

[Steve2020]

NO3 has been decreasing so that may explain it. I run a DND and NO3 has dropped from 18.5ppm to 8.8ppm over the past few months. Thank you.

 

[Randy Holmes-Farley]

That's not a big drop, and will add some alk (0.5 dKH) which would only correspond to about a 10 ppm calcium change.

I expect the effect is a more mundane one of testing/dosing/water change issues messing with observed demand.

 

[Steve2020]

I am not sure what else it can be. I only AWC 2.5gal every other day for a 255gal total water volume. Holding tank saltwater is at Alk=8.9ppm, Cal=450. Other additives added to tank are Reef Actif, RS ABCD and Pods. I use 2 test kits for ALK, RS Pro and Hanna HR. I have been going with RS Pro because Hanna always reads approx .5ppm higher than RS Pro. In the past I used Hanna for Cal but changed to RS Pro because it is easier and both read within 5ppm of each other.
Yesterday I added 260ml of BRS Calcium Chloride to raise it 10ppm and this morning I tested Cal & Alk. Cal went up 10ppm as it should with the addition yesterday and Alk is at 9.0ppm.

 

[spsick]

What dosing pumps are you using? I’m also doing BRS 2 part + part C and have a similar issue of having to add a couple hundred ml but come to find out my dosers move different volume and that was part of it but not all.

 

[Steve2020]

My dosing container is a 3 section container with each section holding 3gal. Alk and Cal levels drop equal amounts in the container so no error in dosing. I check this every few weeks. I mix 1gal at a time in marked jugs so pre mixing is not the issue either unless the BRS pouches have less compounds in them as they should.

 

[Steve2020]

What dosing pumps are you using? I’m also doing BRS 2 part + part C and have a similar issue of having to add a couple hundred ml but come to find out my dosers move different volume and that was part of it but not all.

GHL 2.1 doser. Doser is not the issue as described in my last comment.

 

[spsick]

OK so this begs the question, what are the proportionate calcium and alkalinity levels in the part C?

Tropic Marin defines partc as a sodium free salt mix. if it’s anything like their coral pro salt the alkalinity is not high.

@Lou Ekus any insight on what we are experiencing here?

I am in the same situation with products dosed and a bunch of fast growing SBS corals needing a higher amount of calcium.

 

[Steve2020]

What dosing pumps are you using? I’m also doing BRS 2 part + part C and have a similar issue of having to add a couple hundred ml but come to find out my dosers move different volume and that was part of it but not all.

I see your from the TC area also. Must be the weather causing this issue lol.

 

[Steve2020]

OK so this begs the question, what are the proportionate calcium and alkalinity levels in the part C?

Tropic Marin defines partc as a sodium free salt mix. if it’s anything like their coral pro salt the alkalinity is not high.

@Lou Ekus any insight on what we are experiencing here?

I am in the same situation with products dosed and a bunch of fast growing SBS corals needing a higher amount of calcium.

Great question. I thought TM part C was a Mag supplement with a few other things added but not ALK and CAL.

 

[Randy Holmes-Farley]

OK so this begs the question, what are the proportionate calcium and alkalinity levels in the part C?

Tropic Marin defines partc as a sodium free salt mix. if it’s anything like their coral pro salt the alkalinity is not high.

@Lou Ekus any insight on what we are experiencing here?

I am in the same situation with products dosed and a bunch of fast growing SBS corals needing a higher amount of calcium.

There is no substantial alk or calcium in Part C.

 

[Randy Holmes-Farley]

Great question. I thought TM part C was a Mag supplement with a few other things added but not ALK and CAL.

It is not really a magnesium supplement per se, although that is a main component. It's not causing the observations related to calcium.

 

[Court_Appointed_Hypeman]

That's not a big drop, and will add some alk (0.5 dKH) which would only correspond to about a 10 ppm calcium change.

I expect the effect is a more mundane one of testing/dosing/water change issues messing with observed demand.

Wouldn't the consumption rate increasing to cause the reading to drop by 10ppm be a constant increase on alk assuming that nutrient input is constant?

Unless you accounted for that, I would think thay yes 1 drop from 18 to 8 might add that much all, but also the consumption increasing by that amount constantly, due to nutrient import not changing, would mean the alk production is also increased over time.

I am mostly asking because I have no idea and am only making assumptions here. Not a very educated guess as I do not know the chemical/biological finction of nitrate consumption increasing all.

 

[Randy Holmes-Farley]

I am in the same situation with products dosed and a bunch of fast growing SBS corals needing a higher amount of calcium.

Higher than what?

Assuming you are using my DIY recipe (the BRS soda ash recipe), and it is made and dosed properly, then the only scenarios where more calcium is needed than alkalinity are:

1. Alk is coming from another source (tap water, declining or dosing nitrate, certain other supplements that fail to mention alk boosting, such as Brightwell pH Boost+ or Aquavitro Balance)

2. Calcium is being depleted by water changes using a mix relatively lower in calcium than alk compared to the tank water.

 

[Randy Holmes-Farley]

Wouldn't the consumption rate increasing to cause the reading to drop by 10ppm be a constant increase on alk assuming that nutrient input is constant?

Unless you accounted for that, I would think thay yes 1 drop from 18 to 8 might add that much all, but also the consumption increasing by that amount constantly, due to nutrient import not changing, would mean the alk production is also increased over time.

I am mostly asking because I have no idea and am only making assumptions here. Not a very educated guess as I do not know the chemical/biological finction of nitrate consumption increasing all.

I'm not following, but if nitrate is steady at any level, there is no impact to alkalinity. It must be rising, falling, or being dosed.

A drop from 20 ppm nitrate to 10 ppm nitrate from anything except a water change or sulfur denitrator has a specific alk effect no matter the time frame it happens over.

 

[Court_Appointed_Hypeman]

I'm not following, but if nitrate is steady at any level, there is no impact to alkalinity. It must be rising, falling, or being dosed.

A drop from 20 ppm nitrate to 10 ppm nitrate from anything except a water change or sulfur denitrator has a specific alk effect no matter the time frame it happens over.

I mean, if he is feeding the same amount that got him to 18.8, and it dropped to 8.8 without lowering nutrient input, the overall consumption of nitrate would have increased per day. Meaning there is more alk being produced as a biproduct evey day.

Or does this affect on alk only come as a change in freely available nitrate, and the consumption rate of nitrate has no impact itself on alk.

The logic I am following here is that anarobic consumption of nitrate directly produces Alkalinity. If that is not the function, and alk is only created by a drop in nitrate, and not the constant consumption of nitrate. I might have just had the wrong idea.

 

[spsick]

Higher than what?

Assuming you are using my DIY recipe (the BRS soda ash recipe), and it is made and dosed properly, then the only scenarios where more calcium is needed than alkalinity are:

1. Alk is coming from another source (tap water, declining or dosing nitrate, certain other supplements that fail to mention alk boosting, such as Brightwell pH Boost+ or Aquavitro Balance)

2. Calcium is being depleted by water changes using a mix relatively lower in calcium than alk compared to the tank water.

A higher portion of calcium to soda ash.

I am not dosing anything else to my tank besides your DIY recipe + part c. The only scenario (checking now) I can see is possibly the calcium precipitating in my AWC reservoir. I’m using Red Sea blue bucket and usually check the first couple batches of a new bucket after 24hrs mixing.

EDIT: AWC waster testing at 440ppm so that’s not it.

OP- sorry to clog up your thread I just thought maybe we could identify our common issue.

 

[Randy Holmes-Farley]

I mean, if he is feeding the same amount that got him to 18.8, and it dropped to 8.8 without lowering nutrient input, the overall consumption of nitrate would have increased per day. Meaning there is more alk being produced as a biproduct evey day.

Or does this affect on alk only come as a change in freely available nitrate, and the consumption rate of nitrate has no impact itself on alk.

The logic I am following here is that anarobic consumption of nitrate directly produces Alkalinity. If that is not the function, and alk is only created by a drop in nitrate, and not the constant consumption of nitrate. I might have just had the wrong idea.

Production of nitrate from ammonia depletes alk. Consumption of nitrate (by ANY means) adds it back in exactly of the same amounts.

If nitrate is steady, no net change takes place, regardless of how much fast it is made and then consumed..

And if a change did take place (say, 20 to 10 ppm) then that is a single fixed amount of alk addition.