A Buyer's guide to calcium additives
MATT CLARKE takes a look at some of the calcium additives on the
market.
Calcium is essential to the growth of
coralline algae and most invertebrates, especially corals. It is taken up
rapidly during growth and needs to be replenished regularly. It's just one of a group of water
parameters, including alkalinity, magnesium and salinity, that need monitoring
closely if you keep inverts, and it's important that the levels are maintained
at a concentration similar to that of natural sea water. In the case of
calcium, that's somewhere around the 400 - 420ppm mark. If the levels of these
minerals drop too low, it may have a
detrimental effect on coral growth and health.
In many cases, newly mixed salt water
doesn't even come close to these levels and it's often necessary to replenish
the mineral levels. The chemistry of newly mixed salt water varies according to
the type of salt you use, and the mineral content of the freshwater you mix
with it. Some salts on the market are designed for use with hard, alkaline
tapwater and if they're used in conjunction with RO water, the water produced
will be lacking in certain important chemicals, especially calcium and
magnesium.
There are several salts on the market
designed for use with RO water that contain additional minerals to compensate
for the low mineral content of the water. In many cases, the salt water
produced closely resembles sea water, and in some the calcium and magnesium
levels exceed those found in salt water - something seen as beneficial by most
modern reefkeepers, some of who now aim for calcium levels of 450 - 480ppm. We
tested salt mixes in the September 2001 issue and found that Kent Marine,
Instant Ocean and Reef Crystals produced the best water when mixed with RO.
Supply and demand
How much calcium you need to supply
depends on the calcium demand of your system. If you've got lots of calcareous
algae on your live rock, as well as clams and hard corals, demand is going to
be fairly high. You can get a rough idea of how much is being used by measuring
how much it drops each day or week.
In some large systems containing
significant coral growth, demand could hit 30ppm per day, although it's usually
a lot lower than that.
Calcareous substrates, like coral sand,
crushed coral, cockle shells and dolomite aren't much good for boosting calcium
levels, pH and alkalinity because they don't dissolve until the pH drops below
7.6. Aragonite is better, because it dissolves at pH 8.2, but it's often not
enough to do the job on its own and is only really likely to help maintain
stable levels.
For systems with low calcium demand,
frequent water changes with a mineral-rich salt mix could be enough to maintain
the levels seen in natural sea water.
If demand is higher, or you are aiming for
calcium, alkalinity and magnesium levels beyond those seen in natural sea
water, you will need to supplement these minerals. There are a number of ways
to do this:
Reactors
Calcium reactors are now widely regarded
as the best option, because they'll control the calcium, magnesium and
alkalinity and add trace elements in a balanced fashion. These units generally
sit below the aquarium alongside the sump and need to be fed by a small water pump
and supplied with carbon dioxide (CO2) gas from a pressurized bottle.
By passing water slowly through the
aragonite-filled reactor, and using CO2 to lower the pH, it's possible to
dissolve the aragonite more quickly - allowing it to release lots of minerals
into the water. When running properly, these reactors give superb results. They
are also much safer than some other forms of control and have fewer negative
effects upon overall water chemistry.
Their only real drawback is financial -
once you've bought the gas, regulator, hoses and reactor you're looking at a
bill of at least a couple of hundred pounds, plus some running costs. However,
as our calculations prove, it may actually be more sensible to invest in a
reactor than to use additives if you have a large tank or a high calcium
demand.
Additives
For many people, especially newcomers to
reefkeeping, additives seem to be the easy option. They're often simple to add,
and many are relatively cheap to buy for small systems.
There are dozens on the market, many of
which are based around different concentrations of the same basic chemicals. If
you can't afford to buy a reactor, they're probably the next best bet. However,
many of them can cause imbalances in the chemistry of your water with long-term
use. Some produce excess sodium or chloride which can affect salinity, for
example, and it's easy to throw alkalinity and calcium levels out of balance
with some additives.
There are several different groups of
supplement, each based on slightly different chemicals, and each giving a
slightly different overall chemical change. It's not always clear what you're
getting though. Some manufacturers don't let on exactly what's in their
products, or tell you the concentration they provide, or the sort of increase
in calcium you can expect from dosing a specific amount...
The additives on the market for
replenishing and maintaining calcium levels fall into three main categories:
Kalkwasser
Kalkwasser, or limewater, is a highly
caustic liquid additive made by adding powdered calcium hydroxide (Ca(OH)2) to
fresh water, usually RO. After mixing, the clear part of the solution is added
very slowly to the aquarium to replace evaporational losses. When done
correctly, this can raise the calcium and alkalinity level. When done
incorrectly, it can cause violent pH increases and a drop in alkalinity.
Special gadgets are available to aid both mixing and addition, which make it
much easier to dose than it used to be.
The way kalkwasser reacts with other
chemicals in the water is a little complicated, so the effect it has depends on
the initial chemistry of your system. Kalkwasser reacts with CO2 present in the
water and adds calcium and bicarbonate ions. If there's plenty of CO2 it
produces calcium bicarbonate (which boosts the alkalinity). If there's not
enough CO2, or if the pH is too high, some of the calcium precipitates to
calcium carbonate, which is less soluble. Over time, this will lead to a drop
in alkalinity, which you'll need to counter through the addition of buffers
like sodium bicarbonate.
It can be an effective means of
maintaining good calcium and alkalinity levels, but some reckon it's much
harder to get these to levels beyond those seen in natural sea water,
especially if the rate of evaporation is low and the calcium demand is high.
There is also some evidence to suggest it causes significant internal
differences in coral growth. It can be dodgy in the wrong hands and is really
something for the more experienced reefkeeper.
Calcium chloride
additives
Most of the additives on the market are
probably based on anhydrous or dihydrate forms of calcium chloride - either as
liquids or powders. On its own, calcium chloride pushes up calcium levels, but
it can eventually cause a drop in alkalinity that needs to be countered through
the addition of buffers. Some products contain little else apart from calcium
chloride, while others may be combined with buffers, like sodium chloride, to
help boost alkalinity.
Calcium chloride-based additives can be
useful in tanks with medium or low calcium demand and are often used in
conjunction with other additives, like two-part additives and kalkwasser.
Calcium chloride-based additives can alter the chemistry of the water over
time, particularly if few partial water changes are made.
Our test results suggest that several of
these also contain additional magnesium (no bad thing in itself) - although
this isn't always mentioned on the packaging.
Two part additives
Balanced two-parters, like C-Balance and
Kent's Tech CB, or three-parters like ab Aqua Medic's Reef Calcium, are a
clever and effective way of maintaining good levels of calcium and alkalinity.
They add calcium and alkalinity in balanced ratios without messing up the
balance of the water chemistry. So we think these are the safest bet, if a
calcium reactor is out of the question.
The individual parts are kept in separate
bottles to prevent them from reacting and forming insoluble chemicals.
Essentially, when mixed together they form a sort of salt mix
with a very high calcium level. They always come in liquid form -
if they came as powders moisture in the air would allow the formation of
insoluble calcium carbonate.
Some reefkeepers use calcium
chloride-based additives to provide an initial boost, or to make minor
adjustments, and then maintain those high levels using two-part solutions. Some
of these may cause the s.g. of the water to rise a bit, so keep an eye on it.
The cost of use may be higher than some calcium chloride supplements, but
remember that you're actually dosing more than just calcium, and everything
should be properly balanced.
What to aim for
Opinions differ on optimum levels, but they should always meet, or
slightly exceed, those seen in natural seawater:
> Calcium 400 - 420mg/l
> Alkalinity 7 -10 dKH/ 2.5 - 3.5 meq/l
> Magnesium 1200 -1300mg/l
> pH 8.2-8.3
> Salinity 35-36ppt
Dosing
> Don't dose without testing the calcium, magnesium, alkalinity
and pH first. Even if the manufacturer of the supplement you're using suggests
adding the treatment daily or weekly, you may not need to. The amount you need
to add varies according to the calcium demand of your system.
> It's becoming more common to raise calcium and alkalinity
levels higher than those of natural seawater. But if you raise them too high,
calcium and carbonate will precipitate.
> Magnesium levels are particularly critical when you're dosing
with calcium. They should ideally be between 1300 -1500ppm - any lower and it
may be more difficult to raise the levels of calcium.
> Slightly higher salinity levels allow you to maintain higher
alkalinity and calcium levels.
Our tests
We undertook a controlled experiment on a
range of 18 different calcium additives to examine their short-term effects
upon water chemistry, and performed a number of calculations to determine their
concentration and cost of use for a typical reef tank.
These tests showed only the short-term
effects. Chemical and biological interactions in an aquarium during long-term
use may have different results.
We used aquarium test kits, which while
less accurate than laboratory grade equipment, give a basic representation of
what's happening, although they will have undoubtedly missed some subtle
changes. They also reflect the realistic conditions under which these products
are likely to be used. Few reefkeepers test the chemistry of their water in a
lab. Tests using lab grade equipment and different salt water would clearly
give different results...
We calculated cost of use data based on
the recommended doses required for a hypothetical average reef tank of 120 x 38
x 46cm (48" x 15" x 18"). After 25% of the water has been
displaced by sand and live rock this holds around 160 l./35 gal.
Unfortunately, few companies were willing
to divulge information regarding the composition and concentration of their
products as many deem it commercially sensitive data. So we have not been able
to look at the claimed concentration in every case.
Our results
Based on the results we obtained in the
test, which are specific to our test water, we calculated some statistics on
cost of use by examining the cost of supplying a daily calcium demand of 10ppm
on our hypothetical 160 l./35 gal. tank.
Due to the widely differing concentrations
of these products, and the differences between the claims made on the bottle
and the actual concentrations we achieved in our tests (which could be due to
the initial chemistry of our test water), we found some startling differences
in the cost of use of these products. Based on the water we used for our tests,
the actual cost of most treatments would be between £50 - £110 per year; the
cheapest cost just £20 a year, while some of the less concentrated ranged from
£150 - 435, right up to more than £1000!
But the prices quoted in this review for
the individual products are based on the manufacturers' recommended doses, not
the actual calcium demand of our 160 l. tank. Nor do they take into account the
concentration of the products on test, which varies considerably.
Clearly, because there's a link between
the levels you get and the chemistry of the water you're adding the supplements
to, any results you get on your water will differ from ours. As a result, we'd
recommend buying a small container of your chosen supplement and testing it on
your own system to see how well it performs. You'll need to base your cost
calculations around this.
Seachem Reef Complete
Reef Complete is a blend of ionic calcium
designed to boost calcium levels to those found in natural seawater without
having negative effects on pH, and is claimed to provide strontium and magnesium
at levels equivalent to the rates at which they're depleted.
Seachem provide the breakdown of the product on the bottle, which
is nice to see. The make-up consists of 16% calcium, 0.8% magnesium and 0.016%
strontium. We calculated this to work out at 160,000 mg/l, or some 560 times
more calcium than that available from an equal volume of kalkwasser, plus 8000
mg/l magnesium and 160 mg/l of strontium.
It comes with good, basic dosing instructions and gives three
different treatment regimes based on the reefkeeper's level of experience
(beginner, advanced or expert). Very wisely, Seachem suggest regular testing
and adjusting the dose according to the calcium level of the tank.
The basic maintenance dose for beginners
is 5ml per 80 l./17 gal., added twice weekly. This should raise the calcium
level by around 10 mg/l each time. Based on this dose rate,1ml will treat 16
l./3.5 gal., so a litre will treat 16,000 l./3524 gal.
The expert instructions come with a basic
formula to allow you to determine how much you need to add to raise the calcium
by a set amount, which is very useful. Reef Complete comes in four sizes: 100ml
(£5.20), 250ml (£8.40), 500ml £13.95 and 2 l. (£41.40). It pays to go for the
largest bottle size if you are a heavy user since the price per ml varies from
5.2p (200ml bottle) to 2.07p (2 l. bottle). Based on the recommended dose, for
a 160 l./35 gal. tank, regular bi-weekly doses would cost between £54.08 and
£21.53 depending on the bottle size used.
Seachem Reef Advantage
Calcium
This is a blend of powdered calcium and
carbonates and claims to raise and maintain levels to values similar to those
in natural sea water. It's claimed not to deplete magnesium or alkalinity, and
boosts strontium and magnesium at typical utilisation ratios. Again, this
product comes with a breakdown of constituents. It's claimed to contain
347,000mg/l of calcium (34.7%), 173,000mg/l of magnesium (1.73%) and 346mg/l of
strontium (0.0346%).
There are several different dose rates:
the basic dose is 5ml (one teaspoon) per 150 l./33 gal. twice weekly. Based on
the recommended dose, we estimated running costs for the 250g container at a
standard dose at about £21 each year for our 160 l./35 gal. tank. It comes in
four sizes: 250g (£9.70), 500g (£15.90), 1kg (£27.30) and 4kg (£91.70).
Seachem Reef Calcium
Reef Calcium is a polygluconate complexed
liquid calcium supplement designed to increase and maintain the calcium level
without affecting the pH. It's claimed to be "bio available"; this
means it's presented in a form easily utilised by corals and other
invertebrates and additionally provides them with metabolic energy.
Polygluconate is a derivative of glucose
and is supposed to keep calcium in solution in higher concentrations than
without it. However, some experts claim that gluconates encourage algal blooms.
Reef Calcium contains 5% calcium (50,000
mg/l) and each dose should raise the calcium level by 3 mg/l. A normal dose for
maintaining the calcium level is suggested as 5ml per 80 l./17 gal. As a rough guide,
this should maintain a stable level if the calcium drops by about 24 mg/l per
month - which is probably adequate in the average reef tank but far less than
the amount required in an SPS system with a much higher calcium demand. Based
on the recommended dose a 160 l./35 gal. tank would cost a maximum of £54.08
per year.
The dose can be increased to as much as
15ml per 80 l./17 gal. per day if the demand for calcium is very high - this
should provide enough for a tank with a calcium demand of about 9mg/l per day.
However, if this is the case, your money would be better spent on a calcium
reactor since the cost of use of Reef Calcium under these circumstances would
be prohibitive at more than £200, even when using the largest and cheapest
bottle available.
Reef Calcium comes in four sizes: 100ml (£5.20), 250ml (£8.40),
500ml (£13.95) and 2 l. (£41.40).
Tropic Marin
Bio-Calcium
This powdered supplement contains calcium,
hydrogencarbonate and trace elements in balanced proportions. The instructions
recommend keeping the calcium level below 420ppm to prevent the precipitation
of calcium carbonate, so it's not the ideal supplement to use if you want
really high calcium levels.
The maximum recommended dose rate of 1
level measuring spoon per 18 l./4 gal. is designed to raise the calcium level
by approximately 28ppm. Unfortunately, the instructions don't state how much
the whole container will treat, which makes it impossible to work out exactly
what you're paying for in the shop. TMC told us that one measuring spoon
contains approximately 9.2g of Bio-Calcium, which means that the 500g pot will
treat just under 1000 l./220 gal. and raise the calcium level by 28ppm.
Our hypothetical 160 l./35 gal. tank would
need about 82g to raise the calcium level by 28ppm, which would set us back
around £1.69 per dose, which is quite expensive. The frequency of dosing would
depend on the rate of calcium depletion in your tank. As a guideline, weekly
use on a 160 l./35 gal. tank would cost around £87 a year. Tropic Marin
Bio-Calcium comes in two sizes: 500g (£10.33) and 1.8kg (£23.97).
Salifert Coral Calcium
Coral Calcium contains 160,000 mg/l of
calcium, which is claimed to be the maximum amount it's possible to get in a
liquid supplement, and equates to a concentration of about 16%. It also
contains sodium, chloride, magnesium, sulphate and bromide of pharmaceutical
grade (or higher) in balanced quantities.
It's designed for boosting the calcium
levels, as well as being a long term supplement, and needs to be added at a
rate of 5ml per 100 l./22 gal. This causes an increase of 8ppm in calcium
level. Very wisely, the instructions suggest only raising the calcium level in
small steps of less than 50ppm per day.
Increasing the calcium level by 8ppm on a
160 l./35 gal. tank via a one-off dose would cost about 27p, while raising the
calcium level by 40ppm would cost about £1.34. Based on the recommended dose,
regular weekly doses would cost just under £14 a year, and would cater for a
weekly drop in calcium of around 8ppm - not expensive, but only a very small
calcium demand. Coral Calcium comes in three sizes: 250ml (£8.37), 500ml
(£14.08) and 1 l. (£23.79).
Salifert All in One
All in One, as the name suggests,
increases the calcium, alkalinity and trace element levels simultaneously. It
contains 35,000 ppm, or 3.5%, calcium, plus strontium (700ppm or 0.07%) and
other trace elements including zinc, manganese, cobalt and iron.
The calcium is present as calcium acetate,
which Salifert claim is quickly converted to calcium bicarbonate. It also
contains additional amino acids used by corals during growth.
It's designed to be dosed weekly at 5ml per 100 l./22 gal. Based on
the recommended dose, a 160 l./35 gal. tank would cost around £14 per year, but
it provides less calcium than Coral Calcium. Salifert state that additional
treatments with alkalinity buffers like its KH + pH Buffer may be necessary
during treatment. All in One comes in three sizes: 250ml (£8.37), 500ml
(£14.08) and 1 l. (£23.79).
Salifert Coral Grower
Salifert Coral Grower contains a blend of
calcium and strontium along with a balanced mix of sulphate, chloride, bromide,
sodium, magnesium and trace elements. It's fairly concentrated and contains
around 80,000 mg/l calcium (8%) and 1600 mg/l (0.16%) strontium and claims to
be produced from pharmaceutical grade raw materials
or higher.
Salifert recommend dosing weekly at a rate
of 5ml per 100 l./22 gal., which means that 1 l. treats 20,000 l./4405 gal.
Based on this dose, the smallest bottle size would cost around £13.93 to treat
a 160 l./35 gal. tank each year. Salifert recommend using it in conjunction
with their KH + pH Buffer to supply carbonates. It comes in three sizes: 250ml
(£8.37), 500ml (£14.08) and 1 l. (£23.79).
Rowa Life Elements
Calcium +
Life Elements Calcium + is a new product
marketed under the Rowa brand by D and D Aquarium Solutions. It's a typical
calcium chloride additive, which also contains some additional magnesium to
improve performance. At the time of going to press, D and D Aquarium Solutions
hadn't decided on a retail price for this product, though we were given a guide
price of £19.90 per litre. The recommended dose rate of 10ml per 100 l./22 gal.
twice weekly would cost 32p per dose, or about £33 per year.
Red Sea Reef Success
Calcium+3
Reef Success Calcium+3 contains additional
strontium, molybdenum and iodine and needs to be mixed with freshwater and used
to compensate for evaporational losses, like kalkwasser. It shouldn't be poured
into the main tank in its undiluted form. It doesn't come with any data on the
constituents or concentration, so you'll need to see what happens in your own
system using the recommended doses. It needs to be dosed at a rate of 5ml per
120 l./26 gal. of aquarium water, once each week. On a 160 l./35 gal. tank this
works out at £11.69 per year. Reef Success Calcium+3 costs £13.99 for a 415ml
bottle.
Red Sea Reef Success
Calcium
Reef Success Calcium is a liquid solution
which claims to raise the calcium without affecting the pH or alkalinity. It's
also said to be a balanced supplement and won't affect the sodium and chloride
balance of the water, even after prolonged use. Again, no exact concentration
details are given, but Red Sea do give two different dosages, one for
increasing the calcium level in jumps of 50ppm, and one to maintain a stable
calcium level.
To increase the calcium level by 50ppm you
need to add 15ml per 20 l./4.4 gal over a period of four days. The dose rate
here works out at 1ml per 1.3 l./0.3 gal., making the cost around £12.71 for
the four-day course on a 160 l. system. At the weekly maintenance dose of 5ml
per 120 l./26 gal. the dose rate is about 1ml per 24 l./5.3 gal. This works out
at about £9.18 a year which looks very cheap, but this dose only provides a
fairly small amount of calcium. A 415ml bottle of Reef Success Calcium costs
£10.99.
Red Sea Reef Success
Calk
Reef Success Calk is claimed to be a
balanced supplement aimed to replenish calcium and carbonates in the right
proportions at the same rate as they're removed by invertebrates. It's a
maintenance supplement designed for regular daily or weekly use on water with
an initial calcium level of 380 - 420ppm. The recommend technique for dosing
Calk is to monitor the calcium and alkalinity levels daily for a week to
monitor their decline and determine the approximate rate at which they are
being utilised by the inverts and algae present.
It's dosed at a rate of around 0.5g per
100 l./22 gal., but you need to test the alkalinity regularly and make
adjustments to the amount added depending on the results. No details on
constituents or concentration are provided so we can't comment on how much it's
likely to cost to use or how effective it is at maintaining balanced calcium
and alkalinity levels.
It sells for £11.99 for 500g, and comes with a free Alkalinity Pro
test kit. Calk should be used in conjunction with Coral Trace.
Kent Turbo Calcium
Turbo Calcium is one of Kent's Expert
Series product range and is based on 33-37% anhydrous calcium chloride and is
designed for maintaining a high calcium level. It needs handling carefully as
it can get hot when it's mixed with water. Turbo Calcium comes in three sizes:
200g (£12.25), 400g (£18.75) and 800g (£25.25). This works out at between 3.1
and 6.1p per gram, depending on the container size used.
Kent Liquid Reactor
Kent Liquid Reactor is a new supplement
that the manufacturer claims will "give the same results as a costly
calcium reactor" by boosting calcium, alkalinity, magnesium and strontium
levels. Like Seachem, Kent provide a breakdown of the ingredients.
Liquid Reactor claims to provide 126,000
mg/l (12.6%) calcium and 193,000 mg/l (19.3%) carbonates, so it's a bit more
concentrated than most other liquid supplements on the market.
It needs very thorough shaking before use as some of the contents
settle. However, one shop we spoke to mentioned that they'd had problems
resuspending the material through shaking alone.
Depending on the dose used, a single
treatment on a 160 l./35 gal. tank costs between 21-42p or 13-25p when the
largest bottle size is used. Annual running costs depend on the calcification
rate of the tank, and the dose rate used, but vary between £26.38 and £43.96
when used twice weekly. It clouds the water for an hour or so after addition and
Kent strongly recommend that it's added at night, so you don't have to look at
a cloudy tank and so that it can prevent nightly pH drops. Liquid Reactor comes
in two sizes: 473ml (£24.99) and 1892ml (59.99).
Kent Tech CB Part A and
Part B
This liquid two-part solution, as the
description suggests, comes in two separate bottles.
Two 1 l. bottles treat 15,100 l./3326 gal. You need to add a dose
every day until the target calcium and alkalinity levels are reached. It's
fairly concentrated, 10ml of each part is needed per 151 l./33 gal. Based on
the recommended dose, a one off dose using both bottles on a 160 l./35.2 gal.
costs about 40p. If you need to treat the tank every couple of days it would
cost around £42 a year. Daily use would set you back about £147 a year. Kent
Tech CB comes in two sizes: 16oz Part A and B (£17.98) and 64oz Part A and B
(£43.98).
Kent Liquid Calcium
Liquid Calcium contains a minimum of 10%
calcium as calcium chloride and is described as "bio available". The
dosage instructions could be a touch confusing for UK reefkeepers, since
they're given in teaspoons and US gals, as well as milliliters, with no
conversion information. In a nutshell, a daily dose of 1.25 - 5ml treats 189
l./41 gal. (50 US gal.), depending on the calcium demand of your tank.
For our hypothetical 160 l./35 gal. tank,
daily doses using the 16oz (473ml) bottle would cost around £50 each year. At
the maximum dose it would treat around 37,800 l./8326 gal.
Kent recommend using it in conjunction with Marine Superbuffer dKH
or Pro-Buffer dKH and Strontium and Molybdenum. It comes in three sizes: 8oz
(£8.59); 16oz (£15.50) and 64oz (£40.75).
ab Aqua Medic Reef Life
Calcium
Reef Life Calcium is a balanced three-part
solution. It comes in a boxed set containing three separate treatments
(calcium, trace and buffer tabs), designed to be used in conjunction with each
other to raise the calcium, alkalinity and trace element levels. It raises the
calcium level using calcium chloride, and raises alkalinity using sodium bicarbonate.
Ordinarily, this might interfere with the chemistry of the water by raising the
salinity through an increase in sodium chloride. However, the extra bottle adds
trace elements in exactly the same proportions as Aqua Medic's Reef Salt. This
means that although there's still a slight increase in the salinity, it's not
simply due to the presence of additional sodium, which is much better for the
chemistry of the system, and easily rectified.
What you actually get for your money isn't
stated on the packaging. According to ab Aqua Medic, the separate bottles
provide 162g Ca(HCO3) and 168g of ab Aqua Medic Reef Salt.
Dr Manfred Schluter of ab Aqua Medic told us: "The corals and
other calcium consumers take up the Ca(HCO3) and transform this into calcium
carbonate to build up their skeletons, while the CO2 is used by the
zooxanthellae for photosynthesis. The Aqua Medic Reef Salt component will
produce an increase in the salinity. But, usually, this is not more than the
loss of salt water from protein skimmer waste."
For a basic dose, you need to add 15
tablets and 15ml of each liquid per 400 l./88 gal. each week. This works out at
about 6ml of each liquid and six tablets for a 160 l./35 gal. tank, or just
under £20 per year. Instructions are also provided to allow you to calculate
the amounts required to raise the alkalinity to a desired level. Reef Life
Calcium includes: Reef Life Buffer Tabs (250 tablets), Reef Life Calcium
(250ml) and Reef Life Trace (250ml) and sells for £16. This looks like one of
the better products on the market.
Kalkwasser
Kalkwasser products are simply powdered
calcium hydroxide. Despite what the manufacturers may tell you, there's really
not a huge amount of difference between them, although some may contain more
impurities than others. So, we've not tested them in this review. Those with
fewer impurities tend to command a higher price. Theoretically, these may be a
better purchase, because it's difficult to tell exactly what
"impurities" you're adding. However, it's also said that kalkwasser
can precipitate many impurities out of solution (including phosphate) -
although some chemists dispute that this occurs in saltwater. These impurities
are said to settle out in the white scum that forms when the kalkwasser is
mixed, but aren't present in the clear component of properly mixed kalkwasser.
Rowa Kalk
This is a new calcium hydroxide additive
from D and D Aquarium Solutions. They claim that this is purer than competing
brands on the market at around 99.1% calcium hydroxide.
It comes in two sizes: 500ml (ca. 325g) (£12.95) and 1000ml (ca.
650g) (£17.99). A bulk 5 l. (ca. 3kg) container is also available, which sells
for around £42. Prices range from 1.4 to 3.98p per gram, depending on the
container size used - the cheapest on review here.
Seachem Reef Kalkwasser
This calcium hydroxide product also claims
to have unsurpassed purity and solubility. It comes with easily understood
instructions and dosing information. It comes in three sizes: 250g (£10.50);
500g (£13.20) and 1kg (£25.50). This works out at between 2.55 and 4.2p per
gram.
Kent Marine Kalkwasser
Mix
Again, the distributor claims this product
is purer than competing brands. It comes with good basic instructions on how to
dose safely and what to test for. Kalkwasser Mix comes in three sizes: 100g
(£9.25); 225g (£13.75) and 450g (£18.75). This works out at between 4.16 and
9.25p per gram - twice as expensive as some competing brands in smaller pot
sizes.
Two Little Fishies
Kalkwasser
Two Little Fishies' Kalkwasser comes with
good instructions which explain most of the things to look out for when dosing,
and also provide some handy tips on using it in conjunction with carbon
dioxide. It comes in two sizes: 454g (£17.99) and 1.8kg (£49.95). This works
out at between 2.8 and 4p per gram.
Aquarium Systems Reef
Evolution Calcium Hydroxide
Reef Evolution Calcium Hydroxide
(distributed by Underworld) comes with clear instructions that emphasise the
importance of testing, and of using the clear part of the mixed kalkwasser.
It's available in two sizes: 227g £10.45 and 454g (£17.75). These work out at
between 3.9 and 4.6p per gram.
Two Little Fishes
C-Balance
C-Balance, from Julian Sprung's Two Little
Fishies company and sold in the UK by Underworld, is a two-part solution. It
comes with a breakdown of the contents, which is good to see, and it claims to
adjust the calcium, alkalinity, magnesium and strontium levels in balanced
proportions. The standard dose rate is 5ml of each part per 75 l./16.5 gal. per
day. The maximum recommended dose you can use is 1ml per 3.8 l./0.8 gal., which
needs to be added in two separate additions each day. Daily doses at the
standard rate would work out rather expensive on our hypothetical 160 l./35
gal. tank at about £164 each year - making a calcium reactor look tempting in
this case. However, several of the reefkeepers we spoke to were very
complementary about the composition and performance of this additive during
long term use, and it's considered one of the better products on the market for
safe, balanced dosing. C-Balance costs £19.99 for the two 474ml bottles.
Contacts
Casco (Seachem) - 07000 393940
Underworld (Aquarium Systems) - 01509 610310
D and D Aquarium Solutions (Rowa) - 0208 5012492
TMC (Tropic Marin and Salifert) - 01923 284151
ab Aqua Medic - 0845 090 3500
Aquatic Solutions (Kent Marine) - 01553 776788
Interpet (Red Sea) - 01306 881033
Matt Clarke
Copyright (C) Matt Clarke/Practical Fishkeeping magazine, phone
01733 465204 - fax: 01733 465246 - www.practicalfishkeeping.co.uk
