Calcium at 460ppm and not changing

[MJ59HK]

My calcium has been sitting at around 460ppm for a few months now. Why is it not changing (decreasing)?

I am using Hanna calcium checker and Salifert test kit. Last Hanna checker result was 447 ppm (from about one week ago) and Salifert shows 460ppm from this morning. I was dosing Red Sea Foundation A about 5ml per day for almost 12 months but stopped about a few months back when I realised I was overdosing (for various reasons, but mainly I slacked off and didn't test much). I also dosed Red Sea Foundation B 8-10ml a day to maintain alkalinity of 10 dkH. I don't dose anything else. I changed water once a week - 25% each time. I am expecting calcium level to go down but it's not. Why this?

Other information about my tank: My tank is 4 foot long, has been running for about 3 years, a couple of goniopora corals, a big toadstool, a BTA, a large frog spawn, a few fish (blue tang, sailfin tang, a few chromises, a clown fish, an Australian Stripey and a few snails.

Thanks in advance.

 

[Randy Holmes-Farley]

What do you estimate the water volume to be? Need that to convert the alk dose to dKH per day to then determine an expected calcium consumption rate.

Is the nitrate level changing over time?

 

[MJ59HK]

What do you estimate the water volume to be? Need that to convert the alk dose to dKH per day to then determine an expected calcium consumption rate.

Is the nitrate level changing over time?

It is about 400l or 100G. Nitrate is hovering about 15ppm to 20ppm. Tested it this morning at 17ppm. Cheers.

 

[MJ59HK]

Also I just tested my RODI water using the Salifert test kit. After just adding one drop of Ca-2, the solution turned bright blue. I assume this indicates my RODI water is 0 ppm calcium.

 

[Randy Holmes-Farley]

From Red Sea:

1ml will raise the Alk level of 100 liters (25 gal) by 0.036 meq/l (0.1dKH)

Thus, you are boosting alk by about 0.2 dKH per day, which is a very low dose, and the expected consumption of calcium is less than 1.5 ppm per day. It would take a couple of weeks to detect that by kit, and the water changes can be offsetting it.

 

[MJ59HK]

From Red Sea:

1ml will raise the Alk level of 100 liters (25 gal) by 0.036 meq/l (0.1dKH)

Thus, you are boosting alk by about 0.2 dKH per day, which is a very low dose, and the expected consumption of calcium is less than 1.5 ppm per day. It would take a couple of weeks to detect that by kit, and the water changes can be offsetting it.

This has been going on for a few months now. And each time I changed water, the new salt water has a calcium level of 430ppm. Shouldn't the water change bring down the calcium level much quicker? Cheers.

 

[Randy Holmes-Farley]

This has been going on for a few months now. And each time I changed water, the new salt water has a calcium level of 430ppm. Should the water change bring down the calcium level much quicker? Cheers.

I would not waste worry thinking about it. Calcium has a wide range of acceptability, from at least 400 to 550 pm, and any claims that some particular level is best lacks supporting evidence, IMO.

 

[MJ59HK]

I would not waste worry thinking about it. Calcium has a wide range of acceptability, from at least 400 to 550 pm, and any claims that some particular level is best lacks supporting evidence, IMO.

Hi Randy - I wasn't trying to chase a number but was just wondering why is it the calcium level is not coming down especially with the numerous water changes? Is there something else at play?

 

[Randy Holmes-Farley]

Hi Randy - I wasn't trying to chase a number but was just wondering why is it the calcium level is not coming down especially with the numerous water changes? Is there something else at play?

Unless you are adding calcium in some other way (perhaps which you do not even know) then I expect it is jsut a matter of very low demand. I also expect that if you had been adding the balanced amount of calcium, the level would not be very different because the amount being added is very low.

That said, it is often the case that trying to track down explanations for chemistry things that can include test error, salinity changes, unknown additions, rock and sand slowly dissolving in the water, etc, can be a frustrating exercise without a final answer known.

 

[MJ59HK]

Unless you are adding calcium in some other way (perhaps which you do not even know) then I expect it is jsut a matter of very low demand. I also expect that if you had been adding the balanced amount of calcium, the level would not be very different because the amount being added is very low.

That said, it is often the case that trying to track down explanations for chemistry things that can include test error, salinity changes, unknown additions, rock and sand slowly dissolving in the water, etc, can be a frustrating exercise without a final answer known.

Thanks Randy.

 

[rishma]

One other thing to consider, though you may already have the explanation you need… over the years I have been baffled by and made poor choices based on what eventually turned out to bad test data. Reagents expire and test kits go bad. It has happened to me more than once, to the point when this morning I commented to my wife the my nitrate has not changed at all after a bunch of tests over the last 2 weeks she said…”you sure your test kit isn’t bad?”

And now I am wondering if my test kit is bad….