do regular water changes, maintain calcium, magnesium and other element levels?

[Ballyhoo]

I was just wondering because LFS owner told me that water changes even small ones should be done every week to replenish. I'm pretty sure he meant to replenish calcium, magnesium etc. in my case I pretty clean water because I have a protein scimmer, Matt rollers, etc., so I'm not sure I need to do a water change every seven days, unless it's because I need to replenish the elements. Is that true? Thank you so much.

 

[Randy Holmes-Farley]

In some cases, water changes can usefully supplement some materials. But they cannot ever maintain levels in the salt mix itself and I would not rely on them for alk or calcium.

 

[Ballyhoo]

well, this brings up a very important topic. When should a new reef keeper begin to supplement calcium, magnesium, etc.? Anyways, I'm still not clear on what you meant? Water changes help replenish calcium , magnesium that may have been uptaken by the coral? Confused here I know that with big tanks or with tanks that have a lot of thriving large coral growth that they need to supplement. but what about for newer tanks with smaller coral populations?

 

[bossman818]

Water changes do replenish calcium magnesium and alkalinity. On a mature tank full of coral, water changes might not be enough. Sometimes you will need to dose as corals start growing. Check your numbers and go from there.

 

[JayM]

well, this brings up a very important topic. When should a new reef keeper begin to supplement calcium, magnesium, etc.? Anyways, I'm still not clear on what you meant? Water changes help replenish calcium , magnesium that may have been uptaken by the coral? Confused here I know that with big tanks or with tanks that have a lot of thriving large coral growth that they need to supplement. but what about for newer tanks with smaller coral populations?

Water changes will increase trace elements from where they were pre-water change, but not up to where they were before anything started to use them. I'm probably not smart enough to explain it well, but if you had 100% of the trace elements you wanted when you started with your first fill and livestock used 20% of that, you can't add that 20% back with a fresh batch of water unless you do a 100% water change.

 

[Randy Holmes-Farley]

well, this brings up a very important topic. When should a new reef keeper begin to supplement calcium, magnesium, etc.? Anyways, I'm still not clear on what you meant? Water changes help replenish calcium , magnesium that may have been uptaken by the coral? Confused here I know that with big tanks or with tanks that have a lot of thriving large coral growth that they need to supplement. but what about for newer tanks with smaller coral populations?

Begin to worry about dosing when alkalinity falls below your target level. On a percentage basis is falls faster than calcium and way, way faster than magnesium.

 

[Ballyhoo]

Begin to worry about dosing when alkalinity falls below your target level. On a percentage basis is falls faster than calcium and way, way faster than magnesium.

interesting. But alkalinity is not an element. I learned in basic chemistry and most people know just like when we measure PH, something is either more acidic or more base, and that is the less acidic the more alkaline I thought. So are we just trying to keep things higher on the PH scale? but then, why would we measure both the PH and alkalinity because how are the scales different?.

 

[LohTeK]

You are only diluting the aquarium with a higher level. So technically no but yes. Consistency is more important than number

 

[Randy Holmes-Farley]

interesting. But alkalinity is not an element. I learned in basic chemistry and most people know just like when we measure PH, something is either more acidic or more base, and that is the less acidic the more alkaline I thought. So are we just trying to keep things higher on the PH scale? but then, why would we measure both the PH and alkalinity because how are the scales different?.

No. Alkalinity is used as a measure of things corals critically want, not as anything related to pH.

Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

[note: edited on 5/29/2022 to update the nitrate and phosphate sections with higher recommended levels.] One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There...

www.reef2reef.com

Alkalinity

Like calcium, many corals also use "alkalinity" to form their skeletons, which are composed primarily of calcium carbonate. It is generally believed that corals take up bicarbonate, convert it into carbonate, and then use that carbonate to form calcium carbonate skeletons. That conversion process is shown as:

HCO3- → CO3-- + H+

Bicarbonate → Carbonate + proton (which is released from the coral)

To ensure that corals have an adequate supply of bicarbonate for calcification, aquarists could just measure bicarbonate directly. Designing a test kit for bicarbonate, however, is somewhat more complicated than for alkalinity. Consequently, the use of alkalinity as a surrogate measure for bicarbonate is deeply entrenched in the reef aquarium hobby.

So, what is alkalinity? Alkalinity in a marine aquarium is simply a measure of the amount of acid (H+) required to reduce the pH to about 4.5, where all bicarbonate is converted into carbonic acid as follows:

HCO3- + H+ → H2CO3

The amount of acid needed is equal to the amount of bicarbonate present, so when performing an alkalinity titration with a test kit, you are “counting†the number of bicarbonate ions present. It is not, however, quite that simple since some other ions also take up acid during the titration. Both borate and carbonate also contribute to the measurement of alkalinity, but the bicarbonate dominates these other ions since they are generally lower in concentration than bicarbonate. So knowing the total alkalinity is akin to, but not exactly the same as, knowing how much bicarbonate is available to corals. In any case, total alkalinity is the standard that aquarists use for this purpose.

Unlike the calcium concentration, it is widely believed that certain organisms calcify more quickly at alkalinity levels higher than those in normal seawater. This result has also been demonstrated in the scientific literature, which has shown that adding bicarbonate to seawater increases the rate of calcification in some corals. Uptake of bicarbonate can consequently become rate limiting in many corals. This may be partly due to the fact that the external bicarbonate concentration is not large to begin with (relative to, for example, the calcium concentration, which is effectively about 5 times higher).

For these reasons, alkalinity maintenance is a critical aspect of coral reef aquarium husbandry. In the absence of supplementation, alkalinity will rapidly drop as corals use up much of what is present in seawater. Water changes are not usually sufficient to maintain alkalinity unless there is very little calcification taking place. Most reef aquarists try to maintain alkalinity at levels at or slightly above those of normal seawater, although exactly what levels different aquarists target depends a bit on the goals of their aquaria.

Interestingly, because some corals may calcify faster at higher alkalinity levels, and because the abiotic (nonbiological) precipitation of calcium carbonate on heaters and pumps also rises as alkalinity rises, the demand for alkalinity (and calcium) rises as the alkalinity rises. So an aquarist generally must dose more calcium and alkalinity EVERY DAY to maintain a higher alkalinity (say, 11 dKH) than to maintain 7 dKH. It is not just a one-time boost that is needed to make up that difference. In fact, calcification gets so slow as the alkalinity drops below 6 dKH that reef aquaria rarely get much below that point, even with no dosing: natural calcification has nearly stopped at that level.

In general, I suggest that aquarists maintain alkalinity between about 7-11 dKH (2.5 and 4 meq/L; 125-200 ppm CaCO3 equivalents). Many aquarists growing SPS corals and using Ultra Low Nutrient Systems (ULNS) have found that the corals suffer from “burnt tips†if the alkalinity is too high or changes too much. It is not at all clear why this is the case, but such aquaria are better served by alkalinity in the 7-8 dKH range.
As mentioned above, alkalinity levels above those in natural seawater increase the abiotic precipitation of calcium carbonate on warm objects such as heaters and pump impellers, or sometimes even in sand beds. This precipitation not only wastes calcium and alkalinity that aquarists are carefully adding, but it also increases equipment maintenance requirements and can “damage†a sand bed, hardening it into a chunk of limestone. When elevated alkalinity is driving this precipitation, it can also depress the calcium level. An excessively high alkalinity level can therefore create undesirable consequences.

I suggest that aquarists use a balanced calcium and alkalinity additive system of some sort for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part/three part additive systems.

For rapid alkalinity corrections, aquarists can simply use baking soda (sodium bicarbonate) or washing soda (sodium carbonate; baked baking soda) to good effect. The latter raises pH as well as alkalinity while the former has a very small pH lowering effect. Mixtures can also be used, and are what many hobby chemical supply companies sell as “buffersâ€. Most often, sodium carbonate is preferred, however, since most tanks can be helped by a pH boost.

 

[Ballyhoo]

No. Alkalinity is used as a measure of things corals critically want, not as anything related to pH.

Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

[note: edited on 5/29/2022 to update the nitrate and phosphate sections with higher recommended levels.] One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There...

www.reef2reef.com

Alkalinity

Like calcium, many corals also use "alkalinity" to form their skeletons, which are composed primarily of calcium carbonate. It is generally believed that corals take up bicarbonate, convert it into carbonate, and then use that carbonate to form calcium carbonate skeletons. That conversion process is shown as:

HCO3- → CO3-- + H+

Bicarbonate → Carbonate + proton (which is released from the coral)

To ensure that corals have an adequate supply of bicarbonate for calcification, aquarists could just measure bicarbonate directly. Designing a test kit for bicarbonate, however, is somewhat more complicated than for alkalinity. Consequently, the use of alkalinity as a surrogate measure for bicarbonate is deeply entrenched in the reef aquarium hobby.

So, what is alkalinity? Alkalinity in a marine aquarium is simply a measure of the amount of acid (H+) required to reduce the pH to about 4.5, where all bicarbonate is converted into carbonic acid as follows:

HCO3- + H+ → H2CO3

The amount of acid needed is equal to the amount of bicarbonate present, so when performing an alkalinity titration with a test kit, you are “counting†the number of bicarbonate ions present. It is not, however, quite that simple since some other ions also take up acid during the titration. Both borate and carbonate also contribute to the measurement of alkalinity, but the bicarbonate dominates these other ions since they are generally lower in concentration than bicarbonate. So knowing the total alkalinity is akin to, but not exactly the same as, knowing how much bicarbonate is available to corals. In any case, total alkalinity is the standard that aquarists use for this purpose.

Unlike the calcium concentration, it is widely believed that certain organisms calcify more quickly at alkalinity levels higher than those in normal seawater. This result has also been demonstrated in the scientific literature, which has shown that adding bicarbonate to seawater increases the rate of calcification in some corals. Uptake of bicarbonate can consequently become rate limiting in many corals. This may be partly due to the fact that the external bicarbonate concentration is not large to begin with (relative to, for example, the calcium concentration, which is effectively about 5 times higher).

For these reasons, alkalinity maintenance is a critical aspect of coral reef aquarium husbandry. In the absence of supplementation, alkalinity will rapidly drop as corals use up much of what is present in seawater. Water changes are not usually sufficient to maintain alkalinity unless there is very little calcification taking place. Most reef aquarists try to maintain alkalinity at levels at or slightly above those of normal seawater, although exactly what levels different aquarists target depends a bit on the goals of their aquaria.

Interestingly, because some corals may calcify faster at higher alkalinity levels, and because the abiotic (nonbiological) precipitation of calcium carbonate on heaters and pumps also rises as alkalinity rises, the demand for alkalinity (and calcium) rises as the alkalinity rises. So an aquarist generally must dose more calcium and alkalinity EVERY DAY to maintain a higher alkalinity (say, 11 dKH) than to maintain 7 dKH. It is not just a one-time boost that is needed to make up that difference. In fact, calcification gets so slow as the alkalinity drops below 6 dKH that reef aquaria rarely get much below that point, even with no dosing: natural calcification has nearly stopped at that level.

In general, I suggest that aquarists maintain alkalinity between about 7-11 dKH (2.5 and 4 meq/L; 125-200 ppm CaCO3 equivalents). Many aquarists growing SPS corals and using Ultra Low Nutrient Systems (ULNS) have found that the corals suffer from “burnt tips†if the alkalinity is too high or changes too much. It is not at all clear why this is the case, but such aquaria are better served by alkalinity in the 7-8 dKH range.
As mentioned above, alkalinity levels above those in natural seawater increase the abiotic precipitation of calcium carbonate on warm objects such as heaters and pump impellers, or sometimes even in sand beds. This precipitation not only wastes calcium and alkalinity that aquarists are carefully adding, but it also increases equipment maintenance requirements and can “damage†a sand bed, hardening it into a chunk of limestone. When elevated alkalinity is driving this precipitation, it can also depress the calcium level. An excessively high alkalinity level can therefore create undesirable consequences.

I suggest that aquarists use a balanced calcium and alkalinity additive system of some sort for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part/three part additive systems.

For rapid alkalinity corrections, aquarists can simply use baking soda (sodium bicarbonate) or washing soda (sodium carbonate; baked baking soda) to good effect. The latter raises pH as well as alkalinity while the former has a very small pH lowering effect. Mixtures can also be used, and are what many hobby chemical supply companies sell as “buffersâ€. Most often, sodium carbonate is preferred, however, since most tanks can be helped by a pH boost.

ok a bit of info, like from a fire hose . this is going to take some study because even according to above there is that reference to the ph scale which is the more acidic, the less alkaline vise versa and is measured my ph value. but there is alot of info surrounding this needing a chapter or two from a college text book i think.
for example, I have a Salifert KH test which for me usually measures about 9 or 9.5, but the ph tests usually run somewhere in the 8 range ( been a while since i ran ph). i think i'll need to read the above thread a few times and cross reference the material to understand this.
thanks

 

[ackshee]

ok a bit of info, like from a fire hose . this is going to take some study because even according to above there is that reference to the ph scale which is the more acidic, the less alkaline vise versa and is measured my ph value. but there is alot of info surrounding this needing a chapter or two from a college text book i think.
for example, I have a Salifert KH test which for me usually measures about 9 or 9.5, but the ph tests usually run somewhere in the 8 range ( been a while since i ran ph). i think i'll need to read the above thread a few times and cross reference the material to understand this.
thanks

Honestly the wikipedia page for alkalinity might be helpful reading.

Alkalinity is not the same as pH. They're sort of related, but not the same. Part of the confusion comes from the terminology we use in everyday language. Basic does not equal alkaline.

pH is a measurement of how many hydrogen ions (H+) are in a solution. When you test your pH, that's what you are testing: the amount of hydrogen ions. On the pH scale, things measure from acidic (low pH) to basic (high pH). An acid is a proton donor, it provides an H+ ion. A base is a proton "acceptor."

An alkali is a type of base that is soluble in water. Examples of alkalis are calcium hydroxide, sodium hydroxide, calcium carbonate. By definition an alkaline solution is one which contains alkalis. When you dissolve an alkali in water it splits into a positively-charged ion and a negatively-charged ion. The negatively-charged ion is capable of "grabbing" free H+ ions from the solution, which reduces the acidity, raising the pH. When you test your alkalinity, you are testing your water's capacity to buffer against acidification.

 

[areefer01]

well, this brings up a very important topic. When should a new reef keeper begin to supplement calcium, magnesium, etc.?

As RHF noted on post #6 supplementation happens when the test results fall below your desired levels. Some hobbyist recommend picking a salt that matches your desired parameters of Alk, Ca, and Mg.

Pick up an alkalinity tester and start there. Do a water change. Run a test. Test again at roughly the same time and location in two days, write the result down. Repeat every one to two days for a week or two and you will see your consumption rate.

TL; DR - basically do the water change, test, and look at the trend

 

[Randy Holmes-Farley]

ok a bit of info, like from a fire hose .

My articles detail reef chemistry issues so that folks can go into them in as much depth as they want, but in the case of alkalinity, you need know no more than

"alkalinity is an easy way for reefers to ensure that corals have adequate bicarbonate/carbonate to make their skeletons"

Any relationship to pH is unimportant to that concept and need not be considered at all by most reefers, just as they do not worry much about how a calcium test actually measures calcium. Treat alkalinity and pH as mostly unrelated parameters.

 

[NanoNana]

@Ballyhoo
I’m going to simplify this for you. When reefers talk about alkalinity, they are not referring to it as acid vs base (that is a PH measure not dKH) We are measuring the amounts of bicarbonate available for conversion. Not whether the water is acidic or alkaline. That is over simplified but basic chemistry doesn’t apply here and if you try to use it you’ll confuse yourself further.

 

[Brad Wilkins]

My 6 foot tank has only been running since March this year and has a modest amount of softy, lps and sps colonys. Ive started dosing Kalk 1.46L or 0.39 Gallons a day but have opted for a 100% water changes each month with NSW to replenish Mag and other trace elements. Most would say its overkill but my fish and corals are loving it. Im lucky living in Albany Western Australia, the water quality is superb and i have no need for supplements except for Calcium and Alkalinity. Those levels were dropping pretty rapidly when i stocked the tank so it comes down to how many corals you have and their size in regards to replenishment whether it be through dosing or water changes.

 

[Ballyhoo]

"look at the size of that thing."

 

[Brad Wilkins]

"look at the size of that thing."

Cut the chatter red two!

 

[Hats_]

My 6 foot tank has only been running since March this year and has a modest amount of softy, lps and sps colonys. Ive started dosing Kalk 1.46L or 0.39 Gallons a day but have opted for a 100% water changes each month with NSW to replenish Mag and other trace elements. Most would say its overkill but my fish and corals are loving it. Im lucky living in Albany Western Australia, the water quality is superb and i have no need for supplements except for Calcium and Alkalinity. Those levels were dropping pretty rapidly when i stocked the tank so it comes down to how many corals you have and their size in regards to replenishment whether it be through dosing or water changes.

how do you perform a 100% waterchange on a tank like that I'm curious about

 

[dgc]

I was in the hobby for yrs and set up and maintained many tanks 125 was the smallest up to 750 and 800 gallons
alk,cal and Mag are so very important but I think their are many trace elements a tank gets when doing water changes on a 300 gallon tank we did a 20 to 25 gallon water change every week
If you take out the rock and water displacement of corals they were huge in the tank it prob had 200 gallons of water plus 40 in the sump and so maybe 30% to 40% or so water change every month
Never had any issues with algae or phosphates at all and the corals would need trimmed on a regular basis just growing wild
I think ill still do what I did back in the day with my 180 even if many dont these days Im kinda a if it aint broke dont try to fix it guy

 

[Brad Wilkins]

how do you perform a 100% waterchange on a tank like that I'm curious about

With a setup like this. But i use a 1000L ICB on my trailer and fill it to 780L at an isolated beach. It takes 30 minutes to set up, fill then pack up. Im only 20 minutes to that beach. I then heat it to match tank temp with two 300w heaters and a inkbird temp controller. Ive got a dedicated line through my window and into my return pump. It takes about an hour to drain through a retractable hose and about 20 minutes to fill up. I do fill and empty at the same time when it gets down to 20cm to flush the water through old to new wile maintaining that level so the fish aren't flopping around . Im also rigging up a sprinkler system to run so my corals dont bleach as i noticed a few very small patches from last time i filed. They recovered over two weeks but i don't want to risk it happening again.