A non technical primer
Calcium in the reef tank is not just desirable, it is a requirement, and one that is very on the list indeed. Two main reasons: corals need calcium for growth and survival, calcium is needed to promote sufficient coralline algae growth to keep our tanks free of other undesirable algae.
When the quantity of life forms in the aquarium that require calcium rises, the demand for calcium in your tank will rise at the same time. Not only is the number of animals a factor, but their size is too of course. Indeed, the larger they become, the more likely it is that their need for calcium will be.
Aged tanks and tanks with lots of corals will place a far greater demand on calcium levels than younger tanks and tanks with fewer corals. That should be pretty obvious.
Whereas, at first, this may not have a significant impact on the calcium levels, eventually calcium will fall and the amounts you add to replenish calcium concentrations will not longer suffice.
What I am saying is that the demand for calcium in a tank is not stable, or constant, but fluctuates all the time, and usually rises as time goes by.
The more corals, the more calcium is needed to provide those corals with the calcium they require and maintain calcium levels in the usually recommended ranges at the same time.
This is particularly so when coralline algae suddenly starts to grow all over the tank. Of course any other calcium requiring coral contributes to this phenomenon as well.
Coralline algae may not grow right from the start. They usually do not. Once alkalinity and calcium levels stabilize and once the tank ages somewhat, growth may suddenly take off though.
Once the tank is a few months old and you have all the parameters adjusted, you may suddenly see a rather sizeable increase in their growth (this is especially so if the alkalinity is high or at least higher than what was recommended for some time). This is not unusual and is considered a good development.
Coralline algae appear to spread, and grow more at dKH levels somewhat more elevated than the 7 or 8 dKH level that was recommended for a long time, when hobbyists used Kalkwasser only to increase, or maintain, calcium in the tank.
The advent of two part calcium additives has made it possible to increase not only the calcium ppm level but also the dKH. So has the appearance of calcium reactors.
Hobbyists who have raised their calcium levels to 450+ and their dKH levels to 12 or more, report a far greater growth of coralline algae than those who keep a lower dKH, and no calcium fall outs occur either.
This larger growth requires more calcium additions to maintain these coralline algae healthy and to sustain their further expansion and growth.
The more there are, the more the calcium in the tank becomes depleted and the more rapidly this occurs.
This calls for more testing of calcium levels as the levels will tend to fluctuate more and may necessitate more frequent adjustments.
Also, hobbyists will have to determine how much and what exact type of calcium additive to use to maintain the Calcium ion levels at desired concentrations.
It should be quite obvious that when the calcium demanding bioload increases, the amount of calcium increasing compounds (whatever they may be) that were enough at one time to replenish calcium levels, will no longer be sufficient and you will need to adjust the amounts added.
If more animals and algae lower it by removing it from the water, the hobbyists will have to add more to make up for this depletion (there will be some point of equilibrium reached but that is not the topic of this article).
What was once enough and maintained adequate levels may no longer be. As I indicated, this is more so in aged tanks and in tanks with large amounts of corals and good coralline algae growth.
As the demand rises, the supply of calcium has to be increased.
This fact is often overlooked. Hobbyists who test infrequently then suddenly find one day that their calcium concentration levels are too low.
Or worse, they do not test, keep adding what was enough months earlier, and suddenly find that their corals start to look drab and may even show signs of detaching from their skeletons.
What may happen at the same time is that coralline algae start to die back, or turn white at the edges, or even completely.
In essence, the calcium levels in the tank may have fallen so low that their levels cannot sustain the requirements of everything that is in the tank that requires calcium.
Watch out for this carefully and test you calcium levels regularly and this will not happen to you. It takes far too long to get an aquarium to a state that is considered appropriate for corals and animals, to let it deteriorate because one element is not present in sufficient quantity.
Whenever you add animals or whenever you notice that the amount of coralline algae is increasing, you should test your calcium concentration levels more often, and you should adjust the amount of calcium additive you dispense to compensate for the higher calcium demand.
Where the problem usually starts is from the fact that most hobbyists use limewater to add calcium to their aquariums. They do so by replacing all evaporated water with kalkwasser (limewater). Since evaporation rates stay pretty constant, they are in reality adding the same amount of calcium all the time.
As the demand for calcium increases the amount added in the above fashion may not be enough and supplemental calcium addition may be necessary.
Other calcium adding compounds can be used or the strength of the limewater can be increased by adding the milky solution rather than the clear liquid.
Since there are many other calcium supplements on the market you should have no problem supplementing the KW addition with another such supplement.
Two part calcium additives are probably the way to go to increase the availability and raise the dKH at the same time. Several such products are now available on the market.
Alternatively, and if your are willing to make the investment, or when the value of the tank both financially and otherwise justifies it, add a calcium reactor.
As long as you test regularly, you will know when to adjust the quantity that needs to be added to ensure that your levels stay at concentrations of around the recommended levels.
Calcium in the reef tank is not just desirable, it is a requirement, and one that is very on the list indeed. Two main reasons: corals need calcium for growth and survival, calcium is needed to promote sufficient coralline algae growth to keep our tanks free of other undesirable algae.
When the quantity of life forms in the aquarium that require calcium rises, the demand for calcium in your tank will rise at the same time. Not only is the number of animals a factor, but their size is too of course. Indeed, the larger they become, the more likely it is that their need for calcium will be.
Aged tanks and tanks with lots of corals will place a far greater demand on calcium levels than younger tanks and tanks with fewer corals. That should be pretty obvious.
Whereas, at first, this may not have a significant impact on the calcium levels, eventually calcium will fall and the amounts you add to replenish calcium concentrations will not longer suffice.
What I am saying is that the demand for calcium in a tank is not stable, or constant, but fluctuates all the time, and usually rises as time goes by.
The more corals, the more calcium is needed to provide those corals with the calcium they require and maintain calcium levels in the usually recommended ranges at the same time.
This is particularly so when coralline algae suddenly starts to grow all over the tank. Of course any other calcium requiring coral contributes to this phenomenon as well.
Coralline algae may not grow right from the start. They usually do not. Once alkalinity and calcium levels stabilize and once the tank ages somewhat, growth may suddenly take off though.
Once the tank is a few months old and you have all the parameters adjusted, you may suddenly see a rather sizeable increase in their growth (this is especially so if the alkalinity is high or at least higher than what was recommended for some time). This is not unusual and is considered a good development.
Coralline algae appear to spread, and grow more at dKH levels somewhat more elevated than the 7 or 8 dKH level that was recommended for a long time, when hobbyists used Kalkwasser only to increase, or maintain, calcium in the tank.
The advent of two part calcium additives has made it possible to increase not only the calcium ppm level but also the dKH. So has the appearance of calcium reactors.
Hobbyists who have raised their calcium levels to 450+ and their dKH levels to 12 or more, report a far greater growth of coralline algae than those who keep a lower dKH, and no calcium fall outs occur either.
This larger growth requires more calcium additions to maintain these coralline algae healthy and to sustain their further expansion and growth.
The more there are, the more the calcium in the tank becomes depleted and the more rapidly this occurs.
This calls for more testing of calcium levels as the levels will tend to fluctuate more and may necessitate more frequent adjustments.
Also, hobbyists will have to determine how much and what exact type of calcium additive to use to maintain the Calcium ion levels at desired concentrations.
It should be quite obvious that when the calcium demanding bioload increases, the amount of calcium increasing compounds (whatever they may be) that were enough at one time to replenish calcium levels, will no longer be sufficient and you will need to adjust the amounts added.
If more animals and algae lower it by removing it from the water, the hobbyists will have to add more to make up for this depletion (there will be some point of equilibrium reached but that is not the topic of this article).
What was once enough and maintained adequate levels may no longer be. As I indicated, this is more so in aged tanks and in tanks with large amounts of corals and good coralline algae growth.
As the demand rises, the supply of calcium has to be increased.
This fact is often overlooked. Hobbyists who test infrequently then suddenly find one day that their calcium concentration levels are too low.
Or worse, they do not test, keep adding what was enough months earlier, and suddenly find that their corals start to look drab and may even show signs of detaching from their skeletons.
What may happen at the same time is that coralline algae start to die back, or turn white at the edges, or even completely.
In essence, the calcium levels in the tank may have fallen so low that their levels cannot sustain the requirements of everything that is in the tank that requires calcium.
Watch out for this carefully and test you calcium levels regularly and this will not happen to you. It takes far too long to get an aquarium to a state that is considered appropriate for corals and animals, to let it deteriorate because one element is not present in sufficient quantity.
Whenever you add animals or whenever you notice that the amount of coralline algae is increasing, you should test your calcium concentration levels more often, and you should adjust the amount of calcium additive you dispense to compensate for the higher calcium demand.
Where the problem usually starts is from the fact that most hobbyists use limewater to add calcium to their aquariums. They do so by replacing all evaporated water with kalkwasser (limewater). Since evaporation rates stay pretty constant, they are in reality adding the same amount of calcium all the time.
As the demand for calcium increases the amount added in the above fashion may not be enough and supplemental calcium addition may be necessary.
Other calcium adding compounds can be used or the strength of the limewater can be increased by adding the milky solution rather than the clear liquid.
Since there are many other calcium supplements on the market you should have no problem supplementing the KW addition with another such supplement.
Two part calcium additives are probably the way to go to increase the availability and raise the dKH at the same time. Several such products are now available on the market.
Alternatively, and if your are willing to make the investment, or when the value of the tank both financially and otherwise justifies it, add a calcium reactor.
As long as you test regularly, you will know when to adjust the quantity that needs to be added to ensure that your levels stay at concentrations of around the recommended levels.
