options for increasing Ca and Alk - vinegar, etc

[johns]

Randy (or anyone else with experience that wants to chime in):

I want to try to increase the Ca and especially the Alk in my tank and was wondering which approach you think would be best.

For the first 7 or 8 months with this current tank (when it was mostly soft corals), I was dosing ~25-30ml of 2-part B-Ionic daily (a few people told me I was dosing too much but everything seemed stable). I later started experimenting with dripping a gallon of saturated limewater into the tank with a DIY doser every other day, and doing the B-Ionic on the other days. Readings were Ca: 400 - 420, Alk: 9.5 - 10.5, pH 7.9(morn) – 8.1(evening).

Now I have about a dozen small SPS frags, and I’ve switched over to using a Nilsen kalk reactor for about the past 2 months. I evaporate about 1G of water a day and replace with RO water through the Nilsen. I expected Ca and Alk to be even higher than when I was doing B-Ionic, but my readings seem to have stabilized somewhat at Ca: 350-370, Alk: 7.5-8.5, pH 8.15(morn) – 8.35(evening).

Maybe the current readings are lower because the added SPS frags are putting more of a demand on Ca and Alk? (I’ve never seen any real data on what happens to Ca and Alk when SPS frags are added to an existing system) or maybe it’s just that I’m not adding as much to the system now using the reactor (but is it curious that the pH is actually HIGHER now?).

While I think these levels are reasonable, I’d like to do the best I can to get more growth. I think if I can increase my Ca and especially my Alk to levels where they were while I was doing B-Ionic, I might be giving everything a better shot. However, it looks like I am up towards the high side of pH already, so by going for even higher Ca and Alk, I don’t know if my pH will get out of hand. Which approach would you take? I’m thinking of a few options:

1) start dosing small amounts (5-15ml) B-Ionic daily – While this might be the easiest approach to use, it kind of goes against my ideals. I mean, I set up the kalk reactor hoping that I could avoid any such additions.
2) force more evaporation by installing fan – I’m afraid what this will do to the pH
3) I’ve heard that low Mg might be the cause of not enough Ca and Alk getting into a system. While I haven’t tested it yet, I’m thinking I should and dose Mg if necessary. What do you think? Is this a common reason?
4) I’m interested in maybe adding vinegar to the RO top-off water to get more Ca and Alk in solution, without getting as much of a pH spike. But I cant think of a way to do it. My RO bucket holds about 5 gallons, so enough for 5 days or so. Can I add vinegar to the bucket with each new addition of RO water, every 5 days? Is there another way to get the vinegar in while still using the Nilsen? Alternately, I could drip a gallon of saturated limewater/vinegar every other day or so using my DIY dripper. But like I said above, that adds a lot of work and really messes up my reasons for getting the Nilsen in the first place.

[Randy Holmes-Farley]

Maybe the current readings are lower because the added SPS frags are putting more of a demand on Ca and Alk?

Yes, that is as expected. The reactor may also be delivering less lime than the drip. Is the pH higher now than with the drip, or just than with the B-ionic?

In this situation, I'd boost the calcium up to 420 ppm with calcium chloride or just the calcium part of the B-ionic. This calculator and article will help:

Reef Chemicals Calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm


Then going forward, using B-ionic with the limewtaer is a good option when limewtaer alone isn't enough.

As to the limewater itself, how often are you stirringn the reactor? Have you ever compared the ph of the effluent from it to the ph of saturated limewater (say, 2 teaspoons per a cup offresh water)?

More evaporation is a fine idea. If your pH max is 8.35, then you have a ways to go before being too c oncerned (say, about pH 8.5). You could also just run the fan at night/early morning, when the pH is lowest.

I’ve heard that low Mg might be the cause of not enough Ca and Alk getting into a system. While I haven’t tested it yet, I’m thinking I should and dose Mg if necessary. What do you think? Is this a common reason?

Personally,I think it gets the blame far more often than it is really the problem. Nevertheless, low magnesium can be a cause of excessive abiotic precipitatiuon of CaCO3, and is worth checking.

These articles have more details:

Magnesium
http://www.advancedaquarist.com/issues/oct2003/chem.htm

Magnesium and Strontium in Limewater
http://www.advancedaquarist.com/issues/dec2003/chem.htm


Vinegar is hard to engineer with a Nilsen reactor. Most folks that use it deliver the limewater from a reservoir. You can try adding some vinegar to the RO water (say, 45 ml per freshwater gallon), but when diluted like that, bacteria may consume it in the RO water. They will produce CO2 from the vinegar that can degrade the lime when it is mixed with it. That doesn't happen in vinegar/limewater as the pH is too high for bacteria.

[johns]

Randy-
Thanks for your response (again).

Yes, that is as expected. The reactor may also be delivering less lime than the drip. Is the pH higher now than with the drip, or just than with the B-ionic?

I was never using drip-only. What I was trying to do at the time was alternate 1-gallon drips with 30-ml B-Ionic additions, every other day. Usually, it turned out to be three 1G jugs per week, and four B-Ionic additions on the other days. I dont know that there was much difference in the pH between when I was doing B-Ionic alone compared to when I started alternating it with the 1G drips. But after I strarted alternating, on the days when i did the drips the pH may have been slightly higher than on the B-Ionic days (not much though - the drips were going overnight). The pH now with the Nilsen reactor is most definitely higher though. Even though Ca and Alk have definitley stabilized at a lower level.

In this situation, I'd boost the calcium up to 420 ppm with calcium chloride or just the calcium part of the B-ionic.

Is there a reason why you would want me to boost Ca only and not Alk? Ohh, wait...I know...you dont want me to push the pH up too high. But after reading up a little more, it seems that increasing Alk might have more of an effect on growth rates than just increasing Ca alone. Will increasing Ca alone as you suggest here also help with getting higher Alk at the same time?

Then going forward, using B-ionic with the limewtaer is a good option when limewtaer alone isn't enough.

Is there a way to estimate how much? Or I'll just figure this out empirically.

As to the limewater itself, how often are you stirringn the reactor? Have you ever compared the ph of the effluent from it to the ph of saturated limewater (say, 2 teaspoons per a cup offresh water)?

Nothing is clear-cut simple with my situation (as always). The stirring issue is one I've been wrestling with as well because the reactor I have was custom-made slightly shorter than the normal reactor (I think my mixing chamber is 14 or 15 inches tall instead of a 'standard' 18 inches - in retrospect I wish I hadnt done this because I was doing it for space saving concerns that did not work out anyway). This means that every time I stir, the whole column turns milk white - there is no clear portion at the top (dont know if that is normal??). So, at first I was doing 6 shorter (1min) mixes a day. For the past month or so I switched to 4 longer (2min) mixes a day so that there ws more time to settle between mixes. I dont know if 1 vs 2 min mixing time makes any difference, but longer times in between might allow more settiling. As it stands I never have a totally clear solution at the top. I mean it does settle a lot, but it is always a little cloudy 'off-white' at top, not 'clear' like some people say (again, dont know if this is normal?)

I check the pH of the effluent once after it had been running for about 3 weeks. it was around 11.5. I then added some kalk and tested it after it mixed for a while and it was around 13.

More evaporation is a fine idea. If your pH max is 8.35, then you have a ways to go before being too c oncerned (say, about pH 8.5). You could also just run the fan at night/early morning, when the pH is lowest.

Good idea. Maybe worth a try.

Personally,I think it gets the blame far more often than it is really the problem. Nevertheless, low magnesium can be a cause of excessive abiotic precipitatiuon of CaCO3, and is worth checking.

I think I'll check Mg some time when I get a chance.

Vinegar is hard to engineer with a Nilsen reactor. Most folks that use it deliver the limewater from a reservoir.

How does it get delivered then? Just a gravity drip? I dont think a pump would work well in limewater. I wish i could find a way to make it work with the Nilsen, but it doesn't seem to be a good option.

Do you think it would worth a shot at 45ml per gallon even if it will be sitting in there for 5 days (RT is about 68-70degrees and I can keep it covered from the light).

[Randy Holmes-Farley]

The pH now with the Nilsen reactor is most definitely higher though. Even though Ca and Alk have definitley stabilized at a lower level.

The pH may be higher now, while the net addition of calcium and alkalinity may be lower. B-ionic has a smaller pH rise per amount of calcium and alkalinity added than does limewater.

So it might be that, or the growing frags, or both.

Is there a reason why you would want me to boost Ca only and not Alk? Ohh, wait...I know...you dont want me to push the pH up too high.

That too, but if you used limewater to raise calcium by 70 ppm (350 to 420 ppm), then the alkalinity would try (and fail) to rise by an additional 3.5 meq/L (9.8 dKH) to 17 dKH!. That's why you want a calcium only boost, then continue with the balanced limewater.

Is there a way to estimate how much? Or I'll just figure this out empirically.

Trial and error is the best way. For reference B-ionic is about 65 times more potent than limewater. So 30 mL of each part of B-ionic is about the same as 2 L of saturated limewater.

I check the pH of the effluent once after it had been running for about 3 weeks. it was around 11.5. I then added some kalk and tested it after it mixed for a while and it was around 13.

A drop of about 0.3 pH units is a factor of two in potency. So if the effluent is 1 pH unit lower in pH than saturated limewater, then it is far below saturation.

How does it get delivered then? Just a gravity drip? I dont think a pump would work well in limewater. I wish i could find a way to make it work with the Nilsen, but it doesn't seem to be a good option.

A drip or a pump. I've been using a Reef Filler pump for 9 years (the same one :) ). I do not use vinegar.

I'd work at getting the pH/potency of the limewater up. Adding vinegar won't help at all if the limewater is not already saturated.

[johns]

if you used limewater to raise calcium by 70 ppm (350 to 420 ppm), then the alkalinity would try (and fail) to rise by an additional 3.5 meq/L (9.8 dKH) to 17 dKH!. That's why you want a calcium only boost, then continue with the balanced limewater.

Alk would try to go up to 17dKH, but fail...so where do you estimate that dKH will really get to? I ask, because again, I think it would be nice to get Ca up to 420-450, but I've heard that an increase in Alk can do even more to help growth rates. And I really think my Alk is still low. So by increasing only Ca with no added Alk, I may not be at my optimal point.

Or is there a reason to think that by increasing Ca only to 420, when i then resume with balanced limewater, will there then be a corresponding increase with the Alk at this point as it tries to balance itself out with the increased Ca?

Otherwise, rather than just raising Ca (and rather than using limewater to do it), couldn't I use both parts of B-Ionic to get Ca to 420-450? Where should the balanced Alk be when Ca is between 420-450?

For reference B-ionic is about 65 times more potent than limewater. So 30 mL of each part of B-ionic is about the same as 2 L of saturated limewater.

That's interesting to know. So previously when I was adding 30ml of B-Ionic daily, it was roughly eqivalent to 2L of saturated limewater. Now that I am adding just limewater it is more like 3.5-4.0L per day. And Ca and Alk are STILL lower than before.

A drop of about 0.3 pH units is a factor of two in potency. So if the effluent is 1 pH unit lower in pH than saturated limewater, then it is far below saturation. {/B]

What should the pH of saturated limewater be?

[B]I'd work at getting the pH/potency of the limewater up. Adding vinegar won't help at all if the limewater is not already saturated.

I dont know, I think the limewater must be fully saturated. I added 2 full cups of kalk both times I filled the reactor. Like I said, when it mixes the whole solution turns milk white. Why would it not be saturated?

For what it's worth, the first time I tested the effluent, the pH may have been 11.5 or may have been 12 - the reactor had been set up and running for about 3 weeks. I was starting to think I should add more kalk powder only because my Ca and Alk were reading low (as I discussed) and I could tell the level that was settling to the bottom was getting a little 'thinner' than before (but, honestly, there was still quite a bit there). I really expected that it was still fully saturated based on the amount of kalk powder that was still sitting at the bottom. But I added 2 more cups anyway and let it mix for a while. I tested the effluent again later that day and it was around 13.

What more can i do if you think it may not be saturated?

[Randy Holmes-Farley]

Alk would try to go up to 17dKH, but fail...so where do you estimate that dKH will really get to?

Neither alkalinity nor calcium will rise much. Whatever rise there is, it will be about 20 ppm clacium for every 2.8 dKH. pH will rise some.

So by increasing only Ca with no added Alk, I may not be at my optimal point.

Then boost the calcium with calcium chloride and add extra balanced calcium and alkalinity additive.

Now that I am adding just limewater it is more like 3.5-4.0L per day. And Ca and Alk are STILL lower than before.

Only if that limewater is saturated. You may be adding less.

I would not focus on the exact pH of the limewater, as calibration is poor at pH 12.5. Compare it side by side to truly saturated limewater (2 teaspoons lime in a cup of RO/DI water).

I dont know, I think the limewater must be fully saturated. I added 2 full cups of kalk both times I filled the reactor. Like I said, when it mixes the whole solution turns milk white. Why would it not be saturated?

When stirred, yes it is likely saturated. As soon as it settles, and more fresh water enters, it is no longer saturated.

[johns]

Neither alkalinity nor calcium will rise much. Whatever rise there is, it will be about 20 ppm clacium for every 2.8 dKH. pH will rise some.

Then boost the calcium with calcium chloride and add extra balanced calcium and alkalinity additive.

Is all of this suggestion because my Ca and ALk are not currently 'balanced' properly? Do I need to balance them up first and then start adding them in balance again?

I would not focus on the exact pH of the limewater, as calibration is poor at pH 12.5. Compare it side by side to truly saturated limewater (2 teaspoons lime in a cup of RO/DI water).

Good to know. I will try the saturated solution as a reference point next time when i check the effluent.

When stirred, yes it is likely saturated. As soon as it settles, and more fresh water enters, it is no longer saturated.

But the fresh water enters the chamber slowly. I estimated about 1 cup at each top off event. And it enters the chamber at the bottom pushing the solution out the top. Does fresh RO have a different density than the limewater - will it settle or float to the top of the chamber?

Are there other tricks to getting the kalk fully in solution if you think it may not be fully saturated. or is this all accomplished with mixings? Is there any info out there about whether it's better to mix for longer periods vs. just to mix more frequently.

Do you think it would be ok to just mix a lot more often (like every couple of hours) and not worry about adding more of a slurry to the tank if it's just a small volume (~1 cup) at a time? Could I accomplish higher Ca and Alk this way??

[Randy Holmes-Farley]

Is all of this suggestion because my Ca and ALk are not currently 'balanced' properly? Do I need to balance them up first and then start adding them in balance again?

Yes. The calcium is a bit low, and a balanced additive is not the way to raise it up to normal levels. :)

But the fresh water enters the chamber slowly. I estimated about 1 cup at each top off event. And it enters the chamber at the bottom pushing the solution out the top. Does fresh RO have a different density than the limewater - will it settle or float to the top of the chamber?

Fresh RO is likely a little bit less dense. Regardless, there may not be enough mixing to dissolve much. That's why stirring is needed at all.

Are there other tricks to getting the kalk fully in solution if you think it may not be fully saturated. or is this all accomplished with mixings?

That is a potential drawback of Nilsen reactors: it can be difficult to have the water always fully saturated. During stirring, i expect it dissolves fairly fast. My fresh CaO, at least, dissolves very fast when stirred up. But without mixing, the upper layer of solids may become largely unusable solids that do not dissolve well.

Stirring more often and allowing less time for settling is an option that will help deliver more lime, but also possibly more impurities. If it helps, at least you can be sure what the problem is.

[DougSupreme]

Originally posted by Randy Holmes-Farley

Vinegar is hard to engineer with a Nilsen reactor.

Would you be able to attach a venturi to the mixing pump to draw in vinegar to the reactor? Just an off-the-cuff thought.

[Randy Holmes-Farley]

If it sucked only vinegar, that would be OK, but you do not want to suck in air that way. Controlling the amount of the addition via a venturi may be tricky.

[johns]

Thanks Randy.

I checked my levels again last night.

Ca was 380 and Alk was 8.7dKH. According to the calculator in the link you posted, at this Alk, my Ca should be more like 425.

I added half the volume of liquid Ca to bring it there last night. I will add the other half tonight after testing. After that I am probably going to play around with adding small B-Ionic supplements, changing mixing frequencies and time on the Nilsen, maybe installing my fan on the sump again at some point, or some combination of all of those.

I'm not sure when or if I'll get to the vinegar. In theory it sounds like such a great way to accomplish what I need. In practice, I'm just not sure how to get it to work. Unless I take out my handy DIY drippers again and start alternating doses of 1G jugs of kalk+vinegar instead of the B-Ionic supplements. But that sounds like to much work right now. :rollface:

[Randy Holmes-Farley]

Forget what the calculator says the calcium should be based on the alkalinity. I do not believe that part is important. But you do want calcium to be at about 420 ppm or so, regardless of the alkalinity, and 425 ppm is a fine target.

After that I am probably going to play around with adding small B-Ionic supplements, changing mixing frequencies and time on the Nilsen, maybe installing my fan on the sump again at some point, or some combination of all of those.

That sounds like a good plan. :)

In practice, I'm just not sure how to get it to work.

Yes, I agree, I don't either.

[johns]

Randy- I have a follow-up question.

I used the calculator and Kents liquid Ca to bring levels to around 440ppm. It has stayed stable there for about a week or week and a half. I know this may not be an indication yet for how stable Ca will be long-term, but...

My Alk is still around 8.7dKH, and like I said in my original post, I've heard that increased Alk could do even more for increasing SPS growth than increased Ca. Also, the balanced level of Alk when Ca is 440 is more like 11 dKH.

So should I try to increase Alk now shooting for 10.5 - 11.0 dKH? Can I just use baking soda to do this cheaply? According to the calculator, I will need roughly 3 teaspoons to do this. It also says not to add it all at once - is it really that much of an issue? My pH is still staying between 8.15 - 8.35.

I could also do this with my Alk part of the B-Ionic system, but figured that I might try to do it at a lower cost. Assuming Ca stays relativelt stable now between 420-440, is it acceptable to just check Alk every week, 2 weeks, or month and adjust the dKH to between 10.5 and 11.0 using baking soda? or am I messing with things too much?

[Randy Holmes-Farley]

My Alk is still around 8.7dKH, and like I said in my original post, I've heard that increased Alk could do even more for increasing SPS growth than increased Ca.

Yes, I agree that alkalinity is more often limiting to growth than is calcium. If rapid growth is the goal, then I'd push the alkalinity up to the high side of normal, say 10-12 dKH. Baking soda is an OK way to accomplish a one time boost, but it isn't optimal for routine additions as you'd be better off with a balanced calcium and alkalinity additive system (like a two part additive). Whether calcium appears to be stable or not, you likely do need both calcium and alkalinity boosts.

[johns]

Randy- Thanks again

you'd be better off with a balanced calcium and alkalinity additive system (like a two part additive).

Well I guess I should just bite the bullet and plan on experimenting with small doses of B-Ionic then. Maybe start with 5 or 10 ml daily and then slowly increase. Admittedly, I've been stubborn and reluctant to do this. Not only have I been trying to save a little $$, but I also was striving to get a system that was the most 'self-maintained' as possible, with as few daily manipulations or additions as possible. I got the Nilsen reactor hoping that was all I needed.

Baking soda is an OK way to accomplish a one time boost, but it isn't optimal for routine additions

Not that I dont believe you. I just would like to understand the science - why is this not optimal and what would happen over time if I continued to add small amount of baking soda on a weekly or say, twice per week basis in order to keep boosting up Alk?

[Randy Holmes-Farley]

Not only have I been trying to save a little $$, but I also was striving to get a system that was the most 'self-maintained' as possible

I understand that. I am happy that limewater alone is adequate for my system. It won't help the automation, but if you want to save money, you can make the two part system yourself:

A Homemade Two-Part Calcium and Alkalinity Additive System
http://www.advancedaquarist.com/issues/april2004/chem.htm


Not that I dont believe you. I just would like to understand the science - why is this not optimal and what would happen over time if I continued to add small amount of baking soda on a weekly or say, twice per week basis in order to keep boosting up Alk?

Balanced additives prevent the calcium and alkalinty roller coaster than many, many folks get into, despite a lot of testing.

In this case, the calcium is also being consumed, even if your kit is not accurate enough to detect it. So calcium will decline to the point where you need a big correction. I discuss such issues in this article:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

[johns]

It won't help the automation, but if you want to save money, you can make the two part system yourself:

A Homemade Two-Part Calcium and Alkalinity Additive System
http://www.advancedaquarist.com/issues/april2004/chem.htm

Yes, I have read the article. My first thought was that I didnt have enough time to track everything down and make it. I was probably just being lazy. :o Maybe I should look at it again.

In this case, the calcium is also being consumed, even if your kit is not accurate enough to detect it. So calcium will decline to the point where you need a big correction.

I understand that. But remember I will still be continuously adding Ca via the Nilsen. Just adjusting Alk up slightly when it's not 'in balance'.

Maybe I should ask this question differently - First off, do Ca and Alk decline 'in balance'? Secondly, if I were to bring up Alk to 10-11 dKH or wherever it is presumably 'in balance' with the Ca at 440ppm (according to the calculator), then will they decline together?

If so, and if my Ca is so far remaining stable at 440ppm, I might assume that Alk would remain stable as well. Maybe I only need a one-time correction to bring it up to where they are 'in balance'?

[Randy Holmes-Farley]

But remember I will still be continuously adding Ca via the Nilsen. Just adjusting Alk up slightly when it's not 'in balance'.[?B]

Yes, and it is fine for a once in a while correction. But for everyday use, unless you are adding calcium some how (such as in water changes with Oceanic salt with excessively high calcium), it doesn't get unbalanced in that way. With a few exceptions detailed in the article above, the ways that alkalinity declines also reduce calcium.

[B]First off, do Ca and Alk decline 'in balance'?

Yes, that's the ticket. :)

Secondly, if I were to bring up Alk to 10-11 dKH or wherever it is presumably 'in balance' with the Ca at 440ppm (according to the calculator), then will they decline together?

Yes, but you may not detect the calcium decline. It is only about 18-20 ppm Ca++ for every 1 meq/L (2.8 dKH) of alkalinity.

I might assume that Alk would remain stable as well. Maybe I only need a one-time correction to bring it up to where they are 'in balance'?

Maybe. More likely, you have an ongoing demand for both.