Low Calcium

[Angelfish]

I am unable to raise the calcium level in my tank above 360.

Alk = 9.6, Mg=1350, Ca=360.

The tank is a 90g with a 30g sump.

Additives are: 50 ml each B-Ionic Part 1 and 2 daily, plus 10 ml. B-Ionic Mg daily.

The tank contains no clams and no SPS, only a few softies and a couple of LPS.

There is coralline algae on the glass and on the liverock.

Lighting is provided by 4 VHO bulbs (5 ft long each) - 2 actinic and 2 actinic white, which are on for 12 hours per day.

Can you suggest some reasons why the calcium remains constant at 360 ?

Could you suggest some steps to follow to raise the calcium level ?

[demonsp]

Do you do water changes?
Salt brand.

[scaryperson27]

What's your alkalinity? Does your tank cloud up when you put additives in there?

[rhoptowit]

what test kits are u using?

[Billybeau1]

You are probably just not using enough. 50 ml will not do much in 120 gallons of water. You may either just need to add more or get a more potent calcium chloride like Turbo Calcium or Reef Complete for a one time correction. :)

[bertoni]

This calculator might help:

http://home.comcast.net/~jdieck1/chem_calc3.html

I get about 14 fl oz to raise the calcium to 450 ppm, assuming 70g of actual water volume. I might try half that.

[Angelfish]

Water change regime is 10% per week, using IO salt.
Actual water volume is probably 90g, after figuring in live rock displacement.
There is momentary cloudiness when the alk part of the buffer is added to the sump, but the tank does not get cloudy.
I've tried adding up to 3/4 t. Turbo Calcium per day, which resulted in a temporary increase of Ca to 370. I did this for a month and a half, but Ca did not rise past 370, and I had to be very careful about alk dive when doing this.
Test kits used are Salifert.
There is no skimmer.

[jansenwrasse]

There may be a testing error with the kits you are using. Use the calculator that bertoni posted and double check the results that you have with your test kits from either your LFS or a friend. Maybe increase the dose for a couple of days and see it that helps.

[sjames]

<a href=showthread.php?s=&postid=12592364#post12592364 target=_blank>Originally posted</a> by Angelfish
Water change regime is 10% per week, using IO salt.


IO is low in calcium, try buffering up your water change water to your desired level before changes.

[Angelfish]

Thanks to all who replied.

Test kit was not faulty.

Ca level of IO salt I was using tested at 290.

I am bringing up the Ca level in the water change water before adding to the tank, by using Turbo Calcium.

[bertoni]

What is the SG level, and how is it being measured? Calcium should be at around 350 ppm at 1.026.

[demonsp]

Ph reading will change at night.You need to test in the morning for more accurate reading.

Whats your calcium load or coral?

[Angelfish]

The S.G. is 1.025 measured with a refractometer.

The coral load is light - no sps - some softies and about 4 lps frags.

No clams, but I'd like to have a Deresa.

Calcium is around 350 ppm at 1.026, but to keep a clam, calcium needs to be 400-450, which is why I'd like to raise the Ca.

[Randy Holmes-Farley]

Ph reading will change at night.You need to test in the morning for more accurate reading.

The pH value changes during the course of a day and night, but it is not inaccurate at night.

[bertoni]

How was the refractometer calibrated? Distilled or RO/DI water calibration is inaccurate sometimes:

http://reefkeeping.com/issues/2006-12/rhf/index.php

The PinPoint 53mS conductivity calibration solution is useful for this purpose.

[Angelfish]

I have been using RO/DI water to calibrate the refractometer.

[Randy Holmes-Farley]

A seawater standard would be a more accurate way to go, but the solution to the calcium problem is just adding more calcium supplement, both to the tank and to the new salt mix (not accompanied by an equal amount of alkalinity part of the B-ionic).

[Angelfish]

Hello Randy:

What is a seawater standard and how is i t used ?

In an earlier post, I believe you said that using a 2 part additive is not the way to go, but here it sounds like you are suggesting using B-Ionic.

Could you explain ?

Thanks.

[Randy Holmes-Farley]

The easiest thing to do for refractometer calibration is to buy one from Pinpoint, but you can also make your own. I discuss these options here:

Refractometers and Salinity Measurement
http://reefkeeping.com/issues/2006-12/rhf/index.php

from it:

Commercial Refractometer Standards



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Despite that fact that many refractometers sold to aquarists recommend calibration in pure water, such a calibration alone will not always ensure accuracy. Consequently, other standards may also need to be used. These other standards should be solutions with known refractive indices that are close to the values intended to be measured in the aquarium. For this purpose, seawater with a salinity of 35 ppt is perfect, and such standards can be obtained commercially or made from table salt with appropriate measurement.

One suitable commercial standard is made by American Marine and sold under the brand name Pinpoint. It is sold as a 53 mS/cm calibration fluid for the company's electronic salinity probe (a conductivity probe), but it also is suitable for use in a refractometer. NOTE that this is not necessarily true of all 53 mS/cm conductivity standards. The Pinpoint fluid happens to be made to match seawater in other respects, not just conductivity, but other brands, or do-it-yourself 53 mS/cm standards, may not be appropriate to use with a refractometer because, while they have the same conductivity as 35 ppt seawater, they may not have the same refractive index.

For example, standard seawater with S=35 (35 practical salinity units, or PSU) is defined as seawater with the same conductivity as a solution made from 3.24356 weight percent potassium chloride (KCl), and that conductivity is exactly 53 mS/cm (mS/cm, or milliSiemens per centimeter, is one of the units used for conductivity). That solution, however, has a refractive index of about 1.3371, matching seawater just below 26 ppt. So do not assume that all 53 mS/cm conductivity standards are suitable for refractometer calibration.

Salifert has a product called Refracto-Check that they often give away at meetings like MACNA. It is a 35 ppt seawater refractive index standard, but it is not widely available commercially.

Do-it-yourself Refractometer Standards



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In a previous article I have described how to make a do-it-yourself refractometer standard matching 35 ppt seawater, and I will just summarize that recipe here.

To provide a standard for refractometers requires a solution whose refractive index is similar to normal seawater. Seawater with a salinity of 35 ppt has a refractive index of 1.3394. Likewise, the refractive index of different sodium chloride solutions can be found in the scientific literature. My CRC Handbook of Chemistry and Physics (57th Edition, Page D-252) has such a table. That table has entries for 3.6 and 3.7 weight percent solutions of sodium chloride that span the value for normal seawater. Interpolating between these data points suggests that a solution of 3.65 weight percent sodium chloride has the same refractive index as 35 ppt seawater, and therefore can be used as an appropriate standard (Table 5).


This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.).

This concentration roughly corresponds to ¼ cup (73.1 g) of Morton's Iodized Salt dissolved into two liters (2000 g) of water (giving very slightly more than 2 L of total volume).

For a rougher measurement in the absence of an accurate water volume or weight measurement:

1. Measure ¼ cup of Morton's Iodized Salt (about 73.1 g).
2. Add one teaspoon of salt (making about 79.3 g total salt).
3. Measure the full volume of a plastic 2 L Coke or Diet Coke bottle filled with purified freshwater (about 2104.4 g).
4. Dissolve the total salt (79.3 g) in the total water volume (2104 g) to make an approximately 3.65 weight percent solution of NaCl. The volume of this solution will be slightly larger than the Coke bottle, so dissolve it in another container.

[Note: the standard described here using soft drink bottles is subject to variation in the volume of the bottle. It turns out that such bottles can vary in total volume, and this can lead to at least a one ppt error in the salinity of standards matched to seawater of 35 ppt salinity. Standards made with accurate measurements of salt and water, however, will accurately match 35 ppt.]