Ca 101

[VictorE]

After my fish disaster in this relatively new tank (see Tank of Death threads at http://www.reefcentral.com/forums/showthread.php?p=17316110 and http://www.reefcentral.com/forums/showthread.php?t=1868259)

I need to start getting the chemistry closer to correct as I'm planning on working on the invert population additions while I wait for the ich to disappear.

My basic parameters have been pretty good (Alkalinity, pH, Temp, sg, ammonia, nitrites, nitrates). Now I need to focus on calcium, magnesium (test kit on the way), and strontium (test kit on the way).

My first calcium test (Salifert) told me that I'm at 245. I need to be at 400 or so. I have a calcium reactor that I have not started up yet, but I'm told that this only maintains . . . it does not increase Ca levels.

I have a 320 gallon tank with about 300# of rock. There are essentially three inverts left (I sent the frog spawn back to the LFS to see if it revives) namely a Fiji toadstool, a devil's hand, and mushrooms, all doing well.

What are my options to get the Ca up in increments? I see there is Kalkwasser and there is also calcium chloride.

[bertoni]

Kalk won't work, because it'll add too much alkalinity. Are you sure the test kit is accurate and that you're doing it properly? I'd check some freshly-mixed saltwater as a sanity test. If the number is correct, calcium chloride is the best way to go if you want to dose up the system. Up to 100 ppm per day is safe. This calculator might help:

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

I am fairly skeptical about that calcium result unless the tank has been through a serious precipitation event.

[VictorE]

Kalk won't work, because it'll add too much alkalinity. Are you sure the test kit is accurate and that you're doing it properly? I'd check some freshly-mixed saltwater as a sanity test. If the number is correct, calcium chloride is the best way to go if you want to dose up the system. Up to 100 ppm per day is safe. This calculator might help:

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

I am fairly skeptical about that calcium result unless the tank has been through a serious precipitation event.

Well, it is my first test. I thought it to be suspiciously low as well given that several experienced reefers told me that Oceanic salt, which is what I used originally, typically comes in rather high on Ca, around 500.

[Steve175]

Make sure that the color change is complete on the Salifert Ca test before calling it: e.g., give another few drops (shaking between each and noting color) to make sure that change has completed before making reading.

[VictorE]

Kalk won't work, because it'll add too much alkalinity. Are you sure the test kit is accurate and that you're doing it properly? I'd check some freshly-mixed saltwater as a sanity test. If the number is correct, calcium chloride is the best way to go if you want to dose up the system. Up to 100 ppm per day is safe. This calculator might help:

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

I am fairly skeptical about that calcium result unless the tank has been through a serious precipitation event.

So i tested the DT water again this morning and got the same answer. When I test my new water change mix that I made last week and is still in my Brute trash can, I get an answer around 425.

I would have noticed a precipitation, wouldn't I? Also read the tank of death threads again to get the full history of this young tank. I did a 20% water change two weeks ago. What is eating up all this calcium?

[bertoni]

Precipitation can happen inside pumps, so it's not always visible. If the calcium is that low, usually nothing has been dosed for calcium for a long time, but an alkalinity supplement, including pH buffers, has been used.

A 20% change would tank the tank about 30-40 ppm or so, which isn't much. I'd try dosing some calcium chloride. What is the alkalinity? If the tank is consuming 2 dKH or so per day, which is fairly common, that'd take about 15 ppm out of the water.

How many water changes have been done recently to deal with the tank's various problems? I might be tempted to do a few 20% changes, once per day, to deal with any remaining issues, if that's not been done.

[VictorE]

Precipitation can happen inside pumps, so it's not always visible. If the calcium is that low, usually nothing has been dosed for calcium for a long time, but an alkalinity supplement, including pH buffers, has been used.

A 20% change would tank the tank about 30-40 ppm or so, which isn't much. I'd try dosing some calcium chloride. What is the alkalinity? If the tank is consuming 2 dKH or so per day, which is fairly common, that'd take about 15 ppm out of the water.

How many water changes have been done recently to deal with the tank's various problems? I might be tempted to do a few 20% changes, once per day, to deal with any remaining issues, if that's not been done.

Well it appears you guessed correctly. Spent quite a bit of time with my good friends at BRS this afternoon. Seems I precipitated out the calcium when the LFS kept suggesting that my alk at 125 ppm should be closer to 200. I kept adding Kent Superbuffer 50g at a time to get the level up there. I got one reading one time at 216 ppm but it tends to hover around 150 to 175 ppm. Interesting to note that my 50# bag of bicarb that I use for my pool (added in 50g increments) had little effect on the alkalinity.

BRS told me that bumping up the alkalinity would cause a decrease in Ca since the water can hold only so much of both. That means I can add a Ca suppliment or just do some more water changes (as my new water comes in around 435 ppm Ca).

So that means that I should probably return the Kent Superbuffer and let the tank stay at an alkalinity of 125 to 150??

To answer your question, I did not do many water changes under the presumption that 10 fish and 4 inverts in 320 gallons was almost no bio load and nitrates, nitrites and ammonia stayed at zero. Looks like life is not that simple. Lesson learned as to the necessity of water changes, although I'm still not clear as to the chemistry behind using all this water and salt.

[bertoni]

I would use baking soda instead of the Kent Super-Buffer, but the Kent product is okay. The tank will start consuming alkalinity at a reasonable clip after the calcium is fixed, most likely. Many tanks require daily supplementation. Dosing alkalinity won't drop Ca in any measurable amount if the water parameters are all in their reasonable zone, but alkalinity will allow various organisms to consume calcium in order to grow. Coralline is like that. :)

There are a lot of things going on with water changes:

http://reefkeeping.com/issues/2005-10/rhf/index.php

At this point, removing possible toxins would be high up on the list, IMO.

[VictorE]

I would use baking soda instead of the Kent Super-Buffer, but the Kent product is okay. The tank will start consuming alkalinity at a reasonable clip after the calcium is fixed, most likely. Many tanks require daily supplementation. Dosing alkalinity won't drop Ca in any measurable amount if the water parameters are all in their reasonable zone, but alkalinity will allow various organisms to consume calcium in order to grow. Coralline is like that. :)

There are a lot of things going on with water changes:

http://reefkeeping.com/issues/2005-10/rhf/index.php

At this point, removing possible toxins would be high up on the list, IMO.

So I finished my 25% water change the other day (with lots of drama . . . took 6 hours rather than 1 1/2 since I kept spilling my RO water in the garage)

Retesting gets me alkalinity around 10.8 dKH and calcium of 330.

After reading the link provided, that was my argument when I started this hobby . . . most everything can be filtered out or added into the existing water system (with the exception of nitrates).

There must be more going on that simply is not being measured??:hmm3:

[bertoni]

A 25% water change shouldn't change the parameters all that much. I think the system will be fine. Personally, I'd do two more changes or so at 25%, and then measure the parameters and correct them.

What brand of salt are you using, what is the SG, and has the SG device been calibrated?

[VictorE]

A 25% water change shouldn't change the parameters all that much. I think the system will be fine. Personally, I'd do two more changes or so at 25%, and then measure the parameters and correct them.

What brand of salt are you using, what is the SG, and has the SG device been calibrated?

I started in March with Oceanic (2 - 200 gallon buckets) I used that up about a month ago and bought Instant Ocean a couple of weeks ago. Just finished 1 - 200 gallon box with this last water change and setup of small QT.

SG is now at 1.026 and I'm using a refractometer that has been calibrated.

[bertoni]

Okay, 425 ppm for IO sounds about right.

[VictorE]

Okay, 425 ppm for IO sounds about right.

Received my magnesium tester today along with Magnesium Sulphate and Magnesium Chloride.

Test comes in around 1200 ppm.

I understand that there is a ratio to mix these two together, and if I'm not careful I get precipitation of calcium. What is the ratio?

Salt level and Ca (330) seem to remain the same so far. Alkalinity is still around 9.6 dKh

[bertoni]

There really isn't a ratio, although people post all sorts of numbers. With magnesium at 1200 ppm, the tank will be fine. The canonical ocean average is 1280 ppm. I'd probably raise it to that, but I'm a bit obsessive.

The calcium level shouldn't be allowed to drop below 350 ppm. I would add about 50 ppm or so using calcium chloride.

[VictorE]

There really isn't a ratio, although people post all sorts of numbers. With magnesium at 1200 ppm, the tank will be fine. The canonical ocean average is 1280 ppm. I'd probably raise it to that, but I'm a bit obsessive.

The calcium level shouldn't be allowed to drop below 350 ppm. I would add about 50 ppm or so using calcium chloride.


The Salifert test kit suggests a 1300 to 1500 ppm level, which is why I was asking about raising the level.

I have this giant brand new calcium reactor that has yet to be started up after all this time. How do you determine the drip rate to add to the tank? What is the pH that one should keep the reactor media water at?

Finally, on a completely different note, my 5 gallon QTs are getting 25-50% water changes, yet I still get measurable ammounts of ammonia after two weeks. I haven't tested nitrite and nitrates yet, but I'm curious how this little tank works if there is no rock for other organisms to propogate.

[Paco]

Finally, on a completely different note, my 5 gallon QTs are getting 25-50% water changes, yet I still get measurable ammounts of ammonia after two weeks. I haven't tested nitrite and nitrates yet, but I'm curious how this little tank works if there is no rock for other organisms to propagate.

Nitrifying bacteria will live on the media in your filter. You have some kind of filter in there, right?

[VictorE]

Nitrifying bacteria will live on the media in your filter. You have some kind of filter in there, right?

A really tiny sponge filter, maybe 1" x 3" or so.

[bertoni]

You might need a bigger filter. I never used a filter that small, so I don't know how well it might work.

1300-1500 ppm is a reasonable range, and you can raise to that level if you wish, but I don't think anything higher than 1280 ppm is useful for most tanks.

This page might help tuning a calcium reactor:

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

The tuning will take a fair amount of measurement and tweaking, most likely.

[VictorE]

So, I'm muddling along trying to maintain 2 QT tanks and continue work on the display tank chemistry when today I got a double whammy. First, after dropping the copper levels yesterday in the QTs (since it has been 14 days), ich has reappeared on the tang and the blue jaw trigger. The clowns in the other tank seem to be bullet proof. They could probably survive swimming next to BP's blown out well!

My solution, bring the copper back up and start asking more questions.

The chemistry problem . . . so I come home and see something long and skinny floating in the water of the display tank. Upon closer inspection, it is one (actually 3/4) of one of my T5 super actinic compact fluorescent bulbs that exploded.

So now there is phosphors and mercury in the water.

What are you supposed to do besides a water change (also how large), and how much damage does this do, if any, to the aqua environment?

[HighlandReefer]

Water changes, GAC and running CupriSorb for mercury & phosphors.

[VictorE]

water changes, gac and running cuprisorb for mercury & phosphors.

gac??

[HighlandReefer]

Both will bind with organics in your water column, just like copper and other metals. GAC will remove this.

[HighlandReefer]

I just wanted to double check myself on this. I'm not sure if polyfilters or Curprisorb are more effective at removing mecury. They both will work though, but I'm not sure if there is a lower limit of what mercury polyfilters will remove like with copper. :)

This is a quote from Randy:

"My biggest concern is mercury from the tube. I'm not sure what all the phosphors might be, but they the are likely less of a concern. I'd run carbon and possibly a polyfilter to try to deal with the mercury."

FWIW, mecury is highly toxic in a reef tank. :(

[VictorE]

I just wanted to double check myself on this. I'm not sure if polyfilters or Curprisorb are more effective at removing mecury. They both will work though, but I'm not sure if there is a lower limit of what mercury polyfilters will remove like with copper. :)

This is a quote from Randy:

"My biggest concern is mercury from the tube. I'm not sure what all the phosphors might be, but they the are likely less of a concern. I'd run carbon and possibly a polyfilter to try to deal with the mercury."

FWIW, mecury is highly toxic in a reef tank. :(

I figured mercury is a bad idea in a tank. Fortunately the concentration will be lower since we are talking about 320 gallons of water.

What does GAC stand for?

[HighlandReefer]

Granular Activated Carbon.

For example, you can buy it in bulk from here:

www.bulkreefsupply.com

[VictorE]

Granular Activated Carbon.

For example, you can buy it in bulk from here:

www.bulkreefsupply.com

I have a huge reactor full of it along with another reactor ferric oxide which removes heavy metals. Bought both materials from Ryan @ bulk reef.

[HighlandReefer]

Sounds good.

You may want to change it a little more often then before, for a while. Hopefully you see no negative results. :)

[chuckreef]

While I agree that carbon is a good idea, and I would swap it out every day for a few days too, I think the actual concern is realtively small.

On average there is about 5 mg or les of Hg in a T5 tube and that most of it went off as a gas upon rupture.

Even so 5mg/ (3.78 x 300) = about 4 ppb worst case. This level may be toxic to some inverts, but probably won't harm any fish.

If 90% escaped as a gas upon tube rupture, the level (.1 x4 = .4 ppb) is probably not much of an immediate concern to any of the tank inhabitants.

[VictorE]

While I agree that carbon is a good idea, and I would swap it out every day for a few days too, I think the actual concern is realtively small.

On average there is about 5 mg or les of Hg in a T5 tube and that most of it went off as a gas upon rupture.

Even so 5mg/ (3.78 x 300) = about 4 ppb worst case. This level may be toxic to some inverts, but probably won't harm any fish.

If 90% escaped as a gas upon tube rupture, the level (.1 x4 = .4 ppb) is probably not much of an immediate concern to any of the tank inhabitants.

This Mg answer makes sense to me.

As for the carbon, my reactor holds about 2 pounds at a time. Changing this everyday seems to be overkill as this premium ROX 0.8 Aquarium Carbon.

What about the phosphors? Harmess??

[bertoni]

I don't think the phosphors are very dangerous to humans, so they might not be much of an issue in the tank, but I don't know exactly what might be in the bulbs. If you've changed the carbon a couple of times already, I'd just go back to the normal schedule for replacement.

[chuckreef]

IMO, there is no need to use that much at once. I'd use about 2 or 3 cups a day for a week or so. (Even under normal conditions, I'm not sure that 2 pounds isn't way overkill.) Boomer might be the guy to ask about this. Personally, I use carbon in this pattern:
When not running GFO/phosguard, I use one heaping full cup in a small reactor (for 150 gallon tank) and change it in about three weeks ( a week to ten days sooner would be bettter probbaly). When running GFO, I use just enough to make an even 1/2 inch layer above the PO4 media (about one third to one half cup) and change every four to seven days.

I don't have good info on the nature of the phospors, but I suspect:
1. very little if any actually made it into the tankwater. I beleive most T5 tubes have a coating over (on top of) the phosphor coating. This coating keeps the phpospors in place (on the glass) and, more importatnly helps to keep the Hg from absorbing into the phosphor coating. On a side note, with this coating, T5s should last hobbyists much longer than the old-style T12 and T8 tubes that did not have this newere coating. Those tubes will drop in output by about 1/3 in six to eight months, whereas the new coated t5s should still be close to 95% in 6 months and maybe even at two to three years.
3. The phosphors likely include some toxic metals, but are probably less toxic than the Hg - in general. So lesser concern here.

[VictorE]

IMO, there is no need to use that much at once. I'd use about 2 or 3 cups a day for a week or so. (Even under normal conditions, I'm not sure that 2 pounds isn't way overkill.) Boomer might be the guy to ask about this. Personally, I use carbon in this pattern:
When not running GFO/phosguard, I use one heaping full cup in a small reactor (for 150 gallon tank) and change it in about three weeks ( a week to ten days sooner would be bettter probbaly). When running GFO, I use just enough to make an even 1/2 inch layer above the PO4 media (about one third to one half cup) and change every four to seven days.

I don't have good info on the nature of the phospors, but I suspect:
1. very little if any actually made it into the tankwater. I beleive most T5 tubes have a coating over (on top of) the phosphor coating. This coating keeps the phpospors in place (on the glass) and, more importatnly helps to keep the Hg from absorbing into the phosphor coating. On a side note, with this coating, T5s should last hobbyists much longer than the old-style T12 and T8 tubes that did not have this newere coating. Those tubes will drop in output by about 1/3 in six to eight months, whereas the new coated t5s should still be close to 95% in 6 months and maybe even at two to three years.
3. The phosphors likely include some toxic metals, but are probably less toxic than the Hg - in general. So lesser concern here.

That must have been aragonite that fell out of the bulb when I picked it up off the sea bed; not phosphors. They are bound to the bulb as you said.

As for amount of carbon, I was thinking more carbon just means that the filter lasts longer. Not correct?

[bertoni]

The filtration effect might last longer, or not, depending on a lot of factors. After some period of time, the carbon will be covered with bacteria and stop functioning as a chemical media. Whether adding more carbon adds capacity depends on how much there is in the tank to adsorb, and how quickly the bacteria cover the surface, both of which are going to be variable, depending on the tank.

That's a lot of carbon. I'm not sure I'd be willing to spend that much on the media.

[chuckreef]

Not necessarily. At the very low pressures most of our hobby equipment filters employ, I think we don't really get any hydraulic head forcing the water into the carbon media. So, I think we get mainly surface area adsorption out of our carbon in the reef hobby. Becasue of this (I think) once the carbon surfaces get saturated with absorbed species for a given load of carbon in the reactor - probably just a few days flow, at most - I think the carbon's adsorption rate slows down to where its not really doing much at all. Hence, I think frequent changes of small volumes are the way to go.

In "real" carbon absorption systems, (e.g., industrial waste water trematment systms) where there are real pressures involved (> 50 psi), the hydraulic loading on the bed actually pushes the water into (and through) the carbon matrix using all the carbons pore surfaces. In these systems, the contaminat loading zone (the interface between the spent carbon and the (as yet) actively absorbing carbon) moves downward through the bed as the carbon becomes exhausted. Eventually when the loading zone hits the bottom of the bed, the carbon bed is spent (uou hit breakthrough). Under these conditions, it is actually the depth of the column that most significantly influences/ determines the carbon bed lifetime.

Again, I think others (boomer) may have looked into this more than I have. However, I think most reccomendations you will get on RC will be based upon what's working for folks; and I think 2 pounds at a shot might be above the norm. Perhaps. you can save a few bucks on this point without any negative effects to your tank.

[VictorE]

The filtration effect might last longer, or not, depending on a lot of factors. After some period of time, the carbon will be covered with bacteria and stop functioning as a chemical media. Whether adding more carbon adds capacity depends on how much there is in the tank to adsorb, and how quickly the bacteria cover the surface, both of which are going to be variable, depending on the tank.

That's a lot of carbon. I'm not sure I'd be willing to spend that much on the media.

It was not that much, about $170 and it will last me quite awhile.

[VictorE]

Not necessarily. At the very low pressures most of our hobby equipment filters employ, I think we don't really get any hydraulic head forcing the water into the carbon media. So, I think we get mainly surface area adsorption out of our carbon in the reef hobby. Becasue of this (I think) once the carbon surfaces get saturated with absorbed species for a given load of carbon in the reactor - probably just a few days flow, at most - I think the carbon's adsorption rate slows down to where its not really doing much at all. Hence, I think frequent changes of small volumes are the way to go.

In "real" carbon absorption systems, (e.g., industrial waste water trematment systms) where there are real pressures involved (> 50 psi), the hydraulic loading on the bed actually pushes the water into (and through) the carbon matrix using all the carbons pore surfaces. In these systems, the contaminat loading zone (the interface between the spent carbon and the (as yet) actively absorbing carbon) moves downward through the bed as the carbon becomes exhausted. Eventually when the loading zone hits the bottom of the bed, the carbon bed is spent (uou hit breakthrough). Under these conditions, it is actually the depth of the column that most significantly influences/ determines the carbon bed lifetime.

Again, I think others (boomer) may have looked into this more than I have. However, I think most reccomendations you will get on RC will be based upon what's working for folks; and I think 2 pounds at a shot might be above the norm. Perhaps. you can save a few bucks on this point without any negative effects to your tank.

Does it matter that the carbon column (i.e. the reactor) has an inlet fed from the bottom and all of the media appears to tumble as the water makes its way to the top?

Also, I'm moving a lot of water (25 gallons per minute) 1/4 of which is making its way to the reactors, so if I were to calculate my head pressure, it would be interesting to see what I get.

[chuckreef]

Tumbling means to me there is no pressure on the media. If there were it would be packed in-place.

Is the reactor outlet open-ended? If so, you may have high flow, but not much pressure inside the reactor. At most it would be the max. shut offhead of the pump, but in actuality the pressure in the reactor is probably less than half that value.

[Boomer]

I was asked to come here so.

You do not need crap loads of excessive abouts of GAC as you are just wasting it. The norm is 1/3 cup ROX / 50 gal and for others 1/2 cup and change 1 /m. For his I would think about changing it 1 /w for 1 m. GAC should not be tumbling but barely moving at all. The best way to reduce toxins is not more GAC in a container/filter /reactor but many of them and different water input points in the tank.

Phosphors are bound to the inner surface of the bulb but some can be easily wiped off with your finger at times and feels like a chalk. The elements in some phosphorus are very nasty and would be toxic to aquatic life if it got in the water. Here is a list of a few of them.

http://www.sylvania.com/BusinessProducts/MaterialsandComponents/LightingComponents/Phosphor/FluorescentLamps/


http://www.lamptech.co.uk/Documents/FL%20Phosphors.htm

[VictorE]

So I finished my 25% water change the other day (with lots of drama . . . took 6 hours rather than 1 1/2 since I kept spilling my RO water in the garage)

Retesting gets me alkalinity around 10.8 dKH and calcium of 330.

After reading the link provided, that was my argument when I started this hobby . . . most everything can be filtered out or added into the existing water system (with the exception of nitrates).

There must be more going on that simply is not being measured??:hmm3:

So, two weks later, I'm measuring at 305. Can a calcium reactor be tuned to deal with such a small increment of calcium addition? I have only three inverts in the 320 gallon tank. Not sure if anything else uses calcuim (e.g. algae, snails, etc.)

[VictorE]

Thoughts anyone??

[Paco]

Yes it can. You're going to want to raise it, though, using an additive, before trying to use the CA reactor. I like ot keep my CA around 400 to 450. What's your Alk at right now?

[VictorE]

Yes it can. You're going to want to raise it, though, using an additive, before trying to use the CA reactor. I like ot keep my CA around 400 to 450. What's your Alk at right now?

Looks to be between 7.8 and 8.0. I suspect that when I try to raise calcium, I'm going to continue to lower alkalinity.

I would like to make some calcium booster material from the calcium reactor and use that as my additive, just don't know if it is comparable to any of the packaged materials.

Then of course comes the question of how to keep the alkalinity from dropping further as calcium is added.

Keep in mind that the 320 DT is still fallow (4 fish remaining in 2 QT) and the DT has only two leathers a green star pollip and some mushrooms.

[chuckreef]

You can turn up your CO2 and flow a bit, but I agree with Paco that you would want to manually raise the Ca using calcium chloride and rely on the Ca reactor to maintian the desired levels (mainly alkalinity). Really, they should be called "alkalinity reactors."

[VictorE]

You can turn up your CO2 and flow a bit, but I agree with Paco that you would want to manually raise the Ca using calcium chloride and rely on the Ca reactor to maintian the desired levels (mainly alkalinity). Really, they should be called "alkalinity reactors."

Let me be sure that I'm clear on the current state . . . the reactor is assembled but the CO2 and the recircluation pump is not on. There is water that is flowing through the reactor media and going back into the sump.

I purchased a pH probe two weeks ago to control the CO2 and it was recommended by an experienced reefer that I would want to control the pH in the reactor between 6.7 and 6.9.

Can I make a batch of what appears essentially to be Kalkwaser (after getting the pH inthe reactor to 6.8) and putting some of this water into a separate bucket which I can then add to the tank instead of calcium chloride?

[chuckreef]

I am not sure I am following your post. You can't use actual kalkwater to raise Ca 100 ppm becuase you would likely add way too much alkalinity and would spike your pH too high. Also, you can't make kalkwater with a calcium reactor if that's what you were implying.

You need to put the reactor online to maintain alkalinity unless you are maintianing alkalinity some other way. When you put it online, it will maintain Ca pretty much stable, but becuase your Ca is low now, you will need to raise the Ca manually to the target level (so that you maintain it at the target level, not at the lower (present) level).

[VictorE]

I am not sure I am following your post. You can't use actual kalkwater to raise Ca 100 ppm becuase you would likely add way too much alkalinity and would spike your pH too high. Also, you can't make kalkwater with a calcium reactor if that's what you were implying.

You need to put the reactor online to maintain alkalinity unless you are maintianing alkalinity some other way. When you put it online, it will maintain Ca pretty much stable, but becuase your Ca is low now, you will need to raise the Ca manually to the target level (so that you maintain it at the target level, not at the lower (present) level).

o.k. so a calcium reactor does not make kalkwaser, which is what I was implying. So what is the output of a calcium reactor? If a calcium reactor can maintain a calcium level, I'm at a complete loss to understand why it cannot raise it.

[chuckreef]

Becuase, just as kalk (CaOH2) produces both Ca and alk in a fixed ratio (when disolved/dosed) your Ca reactor produces both Ca and bicarbonte ions simultaneously in more or less a fixed ratio. Hence, presuming your alkalinity is on track and stable, you can't use your reactor to make just a big change in your Ca without also increasing your alkalinity through the roof (at the same time). In other words, when you want to adjust just Ca, (but not alk) you need to use a chemical that does not impact alkalinity, such as Calcium chloride. Similarly, when you want to raise just alkalinity (but not Ca), you would use baking soda, which does not have a Ca component.

[bertoni]

The output of the kalk reactor is tank water plus dissolved calcium carbonate, which, as has been stated, is alkalinity and calcium at the ratio of 1 meq/L per 20 ppm Ca⁺⁺. I agree that calcium chloride is the way to go.

[VictorE]

Becuase, just as kalk (CaOH2) produces both Ca and alk in a fixed ratio (when disolved/dosed) your Ca reactor produces both Ca and bicarbonte ions simultaneously in more or less a fixed ratio. Hence, presuming your alkalinity is on track and stable, you can't use your reactor to make just a big change in your Ca without also increasing your alkalinity through the roof (at the same time). In other words, when you want to adjust just Ca, (but not alk) you need to use a chemical that does not impact alkalinity, such as Calcium chloride. Similarly, when you want to raise just alkalinity (but not Ca), you would use baking soda, which does not have a Ca component.

All makes sense. Since my alkalinity seems low, as I understand all this I would be bumping up both, which I seem to need. From Bertoni's comments it appears that I can only go up 20 ppm Ca and reach the upper limit of alkalinity that a tank should have (which is only another full point in meq/L ).

Am I getting this right?

[chuckreef]

Your alk was around 10.5 to 11. I would not go higher than that.
Sounds like you got it.

[VictorE]

Your alk was around 10.5 to 11. I would not go higher than that.
Sounds like you got it.

Nope, I'm at 7.7 to 8.0 on alkalinity this morning with 305 on calcium (Thursday measurement).

[bertoni]

If your alkalinity is now around 7.8 to 8.0 dKH, then you could only dose 20 ppm Ca⁺⁺ and keep the alkalinity at a sane level.

[VictorE]

If your alkalinity is now around 7.8 to 8.0 dKH, then you could only dose 20 ppm Ca⁺⁺ and keep the alkalinity at a sane level.

O.k. so I'm getting pretty sure I see the ALK/Ca relationship; 1 dKH to 20 ppm Ca.

So if I want to raise both and am limited by raising alkalinity to its upper limit (about 1 dKH), that means a 20 ppm max Ca increase.

What amount of material from an operational calcuim reactor would get me there in this 320 gallon beast?

[bertoni]

That's very hard to judge. Calcium reactors need to be tuned for the correct drip and carbon dioxide injection rates. The amount of material isn't as significant.

[VictorE]

That's very hard to judge. Calcium reactors need to be tuned for the correct drip and carbon dioxide injection rates. The amount of material isn't as significant.

I can understand that to balance it is a trial and error. It seems to me that if you know from experience that the ratio of changing Ca and alkalinity is 20ppm:1 dKH, then someone must have figured this out using a loaded reactor with the "brine" solution being maintained at a specific pH (which is how I understand I will be regulating the CO2 feed).

Secondarily, if the ratio is 20:1 going up (in calcium concentration and alkalinity), do reef tanks in general consume Ca and Alkalinity at this rate as well? If not, how does the drip from the reactor maintain the balance?

[VictorE]

Kalk won't work, because it'll add too much alkalinity. Are you sure the test kit is accurate and that you're doing it properly? I'd check some freshly-mixed saltwater as a sanity test. If the number is correct, calcium chloride is the best way to go if you want to dose up the system. Up to 100 ppm per day is safe. This calculator might help:

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

I am fairly skeptical about that calcium result unless the tank has been through a serious precipitation event.

So, I'm playing with the calculator and am trying to adjust my parameters.

I've tried several times to measure the alkalinity of the effluent to no avail. It is clearly off the charts as my Salifert test kit says it is more than 16 dKh and even if I shoot a second full ml, ther eis still no color change.

Suggestions on how to measure effluent alkalinity?

[bertoni]

It might take several syringes to measure the dKH of the effluent. You could try diluting it with 3 parts RO/DI water to one part effluent, and then multiply the results of testing that by 4.

[VictorE]

It might take several syringes to measure the dKH of the effluent. You could try diluting it with 3 parts RO/DI water to one part effluent, and then multiply the results of testing that by 4.

Interesting idea, but would I not need to also know the alkalinity of the RO/DI water in order to get the right reading?

[bertoni]

The alkalinity of RO/DI is zero, unless the filters are shot.

[VictorE]

I'm struggling again with calcium as things are not behaving as expected. Calcium is going up despite turning off the reactor. Here are my data points . . . I'm shooting for 8.0 and 425. Perhaps I still do not appreciate how these are tied together in this 320 gallon tank.

date........alk.................Ca..............action taken after test results

8/23........7.0 dKH........380 ppm........(added 54g sodium bicarb and 200g of Ca)
8/24........9.0 dKH........440 ppm
8/26........8.0 dKH........440 ppm
8/28........8.0 dKH........445 ppm........(shut off reactor)
8/30........7.7 dKH........470 ppm........???????

Am I in trouble here?

[bertoni]

That's not a big change in calcium, and a lot of that might be due to noise in the test kits. I wouldn't worry yet. Calcium can't go up unless it's added. The usual suspects are water changes with a high-calcium salt or tap water, assuming you've stopped all direct supplementation.

[VictorE]

That's not a big change in calcium, and a lot of that might be due to noise in the test kits. I wouldn't worry yet. Calcium can't go up unless it's added. The usual suspects are water changes with a high-calcium salt or tap water, assuming you've stopped all direct supplementation.

I'm using the Salifert kits which strike me (being a novice) as being overly minute in the measurement. No water change during this period.

470 ppm Ca is not too high?

Also if alkalinity drops, any effect on the calcium measurement even if no calcium precipitates out of solution due to the alkalinity drop?

[bertoni]

At best, the Salifert kits have a resolution of 8 ppm, so a 15 ppm difference could be chance. 470 ppm generally won't cause any problems.

A drop in alkalinity only affects calcium if the drop corresponds to calcification. So if you dose some HCl into the tank, the alkalinity will drop, but the calcium will remain unchanged.

[Boomer]

O.k. so I'm getting pretty sure I see the ALK/Ca relationship; 1 dKH to 20 ppm Ca.

No, that is 1 meq / l / 20 ppm Ca++ or 2.8 dKH / 20 ppm Ca++

[VictorE]

O.k. so I'm getting pretty sure I see the ALK/Ca relationship; 1 dKH to 20 ppm Ca.

No, that is 1 meq / l / 20 ppm Ca++ or 2.8 dKH / 20 ppm Ca++

If I understand the relationship then, it seems to me that the measurements between 8/28 and 8/30 make sense. Since alkalinity dropped by 2.7, calcium went up. Do I have this right?

When I shut off the Ca reactor did I stop buffering the water or did I just stop adding calcium, or something in betwen?

[Boomer]

No, Vic, it means that if your Ca++ drops 20 pm the Alk will drop 2.8 dKH. When you shut the reactor off you did both. What is /was the pH of the reactor effluent ? When you shut off the reactor you may have flushed some particulates in to the tank water. These can give funny readings on test kits. Monitor the tank over the next few days to see how things pan out. I agree with Jon it may just be some kind of testing error.


Since it is or was a reactor, some help here


A Guide to Using Calcium Reactors
http://reefkeeping.com/issues/2002-05/sh/feature/index.htm

Calcium Reactor Setup Help and Calculator
http://reef.diesyst.com/reactor/reactor.html

[VictorE]

pH is kept between 6.7 and 6.9 using a Reefkeeper controller and an electrically controlled valve on the CO2 bottle.

Started the drip a few weeks ago at 1ml per minute (a drop every seven seconds). Increased that to a drop every 4 seconds about 10 days ago until I shut the reactor off on Saturday.