Calcium Hydroxide | "Kalkwasser" ApplicationReview Disclaimer at the bottom of this page prior to use. Keep out of reach of children and unauthorized persons. Avoid contact with skin, eyes, and mucous membranes. Store in a cool, dry location away from sunlight. Do not inhale dust.
The
following discussion and recommendations are made expressly for
recirculating systems. Laboratory application may proceed as required
by study objectives. Review Disclaimer at bottom of page prior to using
this or other Captiv8 Aquaculture product(s).
Your system's water chemistry and safety is your responsibility.
Calcium hydroxide addition to any solution, including system water,
will increase pH. Excessive addition may result in system pH increasing
beyond the value tolerated by cohort members. Review the entire
contents of this page prior to using Isol8 Ca(OH)2. Address any
questions by contacting us, directly, prior to application.
While there are some
preparatory steps required when using calcium hydroxide in systems
housing cohorts comprised of reef building invertebrates, users
are rewarded with greater pH stability (assuming that the dosing
procedure below is adhered to) and, generally, greater rates of
calcification than in systems not employing this calcium source.
Users often find that the requirement to boost alkalinity is decreased
in systems dosed with calcium hydroxide solution as a means of pH
management.
Mixing and Dosing Procedure:
-
Calcium hydroxide and its
solutions are skin and membrane irritants. Do not handle these
substances without proper personal protective equipment. The pH of saturated calcium hydroxide solution is ~12.4 for T=25°C / 77°F.
-
Obtain
a clean mixing vessel, such as a pail or jerrican, that can be covered
or closed with a lid, with a capacity of 2 - 10 gallons. Recommended is
to prepare enough solution to last up to 48 hours worth of dosing;
required solution volume is system dependent and is a factor of pH
change per unit time, so initially it is recommended to prepare 1 gallon
of solution and then adjust this volume as system requirements dictate.
-
Isol8
Ca(OH)2 must be thoroughly mixed (using a long-handled plastic spoon or
mixing paddle) into purified water at the rate of 6.50 g / 1 gallon
(assuming T=25°C / 77°F) and allowed to settle for 15 minutes, or until
the solution becomes clear. Place a lid on the mixing vessel to
mitigate the interaction of the air space immediately above the solution
with atmospheric CO2. Resist the temptation to prepare more solution
than is required for 48 hours, as CO2 interaction with the solution will
result in solution weakening.
-
Draw the calcium hydroxide solution from the vessel via dosing pump (e.g. peristaltic pump), the operation of which is regulated entirely by a calibrated pH controller (not by a timer).
As previously noted, the pH of saturated calcium hydroxide solution is
~12.4 at a temperature of 25°C / 77°F; resultantly, this solution must be dosed via pH controlled application,
as dosing with a timer can result in system pH exceeding a maximum
allowable value (in recirculating marine ecosystems, we recommend a
maximum pH value of 8.40).
-
Initially,
locate the controller's pH probe in close proximity to the solution
discharge point, enabling the controller to rapidly react to the change
in system pH as the solution is dosed. With time, the distance between
the probe and the discharge point can be modified to enable the solution
to enter the system without driving the pH value above the allowable
maximum.
-
The
solution should be dripped into the system in a location where it will
be dispersed throughout the system via steady water flow, such as near a
return pump intake. The rate of solution addition should not cause the
system pH to exceed the maximum allowable value by more than 0.02.
Perform regular calibration of the pH controller to maintain maximum
accuracy.
Notes:
-
Do not drip calcium hydroxide
solution in close proximity to sessile invertebrates or developing
finfish embryos. Monitor cohort for signs of distress when increasing
average system alkalinity and pH, and decrease or halt rate of dosing if
distress is noticed. Do not increase average system pH value by more
than 0.10 per 12h. Aside from emergencies (e.g. excessive nutrient
content in an active system, greatly depressed or excessive salinity,
etc.), gradual changes in water composition are generally tolerated
better by aquatic organisms than are rapid changes.
-
If using the recommended ratio
of 6.50 g calcium hydroxide to 1 gallon purified water, then the
solution should become clear with little or no undissolved material
remaining on the bottom of the vessel. Keeping the vessel covered and
taking steps to mitigate interaction with atmospheric CO2 slows the
degradation of the solution strength, however there will eventually be
sufficient interaction with CO2 to cause precipitation of calcium
carbonate. It is for this reason that preparing a maximum of 48-hours'
worth of solution is recommended. Precipitant which has formed and
settled out of solution onto the bottom of the vessel will not
significantly interact with the solution between emptying and cleaning
the vessel (once every one to four weeks is generally recommended,
depending upon rate of use and purity of water employed in solution
preparation), and may be discarded when performing vessel cleaning.
-
If using a greater mass of
calcium hydroxide than 6.50 g per 1 gallon water, then the undissolved
solute must be allowed to settle to the bottom of the vessel, and the
solution that is drawn by the peristaltic (or other type) dosing pump
must be from above the layer of undissolved material. In this case, if
using a float valve or similar means to maintain a static volume of
solution in the vessel, then understand that the strength of the
solution will gradually decrease (unless employing a stirring
apparatus), resulting in ever-increasing volume of solution being dosed
to maintain pH and, consequently, decreasing salinity of the system.
The rate at which saturated
calcium hydroxide solution is dosed is a factor of system acidification,
itself being driven by various chemical and physical factors which are
unique to each independently-operating recirculating system, and which
are constantly changing as cohort biomass increases and decreases.
Among the factors involved are: abundance and decomposition rates of
DOM and POM; addition of carbon dioxide, yielding carbonic acid, in
conjunction with calcareous media reactors; rate of gas exchange and
immediate atmospheric CO2 content;
application of substances which feature a low pH (e.g. shelf-stable
organic solutions); average alkalinity (carbonate hardness) value;
balance of CO2 production and
uptake as a matter of rates of aerobic respiration and photosynthesis,
respectively. While this is not an exhaustive list of factors
influencing pH in recirculating systems, these factors may collectively
be of greatest consequence in the daily management of pH values.
The unique nature of each
individual recirculating system dictates that pH be monitored and
maintained within the appropriate range, as dictated by cohort
requirements and desired ammonia : ammonium balance. Alkalinity, which
may be functionally defined as the relative stability of pH, deserves
similar daily attention from the caretaker(s) of recirculating systems. Disclaimer Notice:
It is not possible to eliminate all risks associated with the use,
handling, or storage of this product. Ineffectiveness, injury to crops
and/or livestock, or other unintended consequences may result due to
factors outside the control of Captiv8 Aquaculture or the seller. Buyer
or user shall assume all such risks. For details, go to Terms and Conditions. Consult SDS before use.
Disclaimer: Captiv8
Aquaculture warrants that this product conforms to the description, and
is reasonably fit for the purposes described, on its label. In no event
shall Captiv8 Aquaculture or the seller be held liable for any
incidental, consequential, or special damages, loss, or injury,
including, without limiting, lost profits, resulting from the use or
handling of this product. The exclusive remedy of the buyer or user for
all claims shall be the return of the purchase price of this product.
Express and implied warranties are disclaimed. Captiv8 Aquaculture does
not authorize any agent or representative to make any other warranty,
guarantee, or representation concerning this product.
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