Help with Alk/CA/pH... GARY!

[Bill S]

OK, I've got to get a handle on this in my 215.

I use Kent Salts. My parms:

pH: 8.3 +/-
Ca: 320 (I'm dosing 2 gallons of Kalk a night - I'm thinking this is a waste...)
Alk: 2.5 meq/l

Based on the Reef Chemistry Calculator, it says I need:

42 teaspoons of CaCl (I have about 15lbs of Dow Flake from mikeyboy)
69 teaspoons of Bicarb. Should I bake this first?

Should I do the bicarb first - in thirds or quarters per day, and then the CaCl?

Also, I have a Ca reactor and some other stuff I don't know what it is. Anyone identify? Anyone have some ideas on setting up the Ca Reactor?

THANKS!

[aquadoc]

bottom pic consists of a dyi kalk reactor, and the small black canister next to it is a phosban reactor.

[matt]

Keep dosing the KW, it's not a waste, but KW alone will not raise your calcium level quickly. Since your calcium is lower than your alk, I'd start by dosing the equivilent of about 4 tablespoons of turbo calcium; maybe that's about 6 tablespoons of dowflake, I'm not sure exactly. Mix it up in some R.O. water and pour it in slowly, or better yet, drip it in. Later that same day, dose 4 tablespoons of baking soda, same way. You don't need to bake it because your ph is fine and even if the baking soda lowers it a little, the KW will take care of that. Do this every day for a few days until you've reached the target (there's about 3 teaspoons in a tablespoon I believe) and test again. I bet you'll need less that 69 teaspoons of baking soda.

A calcium level over 400 is not really necessary as long as you can keep it there; ditto for alk over 3.0-3.5.

You can spike your KW with a little vinegar; I think a limit on that is around 20ml/gallon. I used to do that and it helps in a couple of ways; one, it increases the solubility of calcium hydroxide in water, which makes your KW stronger, and two, it increases the amount of KW you can safely dose without raising your ph too high.

Even if you set up the calcium reactor, you'll want to start with your levels where you want them, using the reactor only to maintain levels. If you do set up the reactor, I think it would be a good idea to do some research to see what media people are currently using. Back when I was making lots of calcium reactors and using one, ARM was pretty popular but I bet there's something around now that's better.

[Bill S]

Thanks all, and THANKS Gary for the phone call. I'm doing 1/3 of the dose at a time, alternating between the 2. This morning my alk was up to 3.5-4.0.

[GaryP]

You can spike your KW with a little vinegar; I think a limit on that is around 20ml/gallon. I used to do that and it helps in a couple of ways; one, it increases the solubility of calcium hydroxide in water, which makes your KW stronger, and two, it increases the amount of KW you can safely dose without raising your ph too high.

Just a small correction on this, if I may. First, viengar neutralizes Kalk to produce calcium acetate. Calcium acetate is a lot more water soluble then Kalk so it does raise your calcium level. However, unless you add enough vinegar to completely neutralize all of the Kalk in the container the pH will still be the same as regular Kalk (~12-13). More Kalk will simply dissolve to take the place of the neutralized material.

Second, Kalk contributes both calcium and alkalinity. When you add vinegar, you no longer get the alkalinity contribution from the neutralized material, only calcium. The acetate does act as a pH buffer and as a food source but you no longer get the carbonate needed by stony corals. That is not to say that the you are not getting alkalinity from partially neutralized Kalk. You are still getting about 3% solubility like you would from unneutralized Kalk.

Note: Kalk neutralizes CO2 (carbonic acid) to form carbonate.

H2CO3 (carbonic acid) + Ca(OH)2 ---> 2 H20 + CO3

The Kalk - Vinegar Reaction (if anyone cares):

Ca(OH)2 + 2 CH2COOH (acetic acid) ----> Ca(CH2COO)2 + 2 H20

[Bill S]

OK, after dosing twice each of (about 225 gallons including sump, less rock & sand):

15 teas bicarb/3 teas washing soda
14 teas Dow Flake (CaCl)

I've gone from:
Alk 2.5 to 4.0
Ca 320 to 340

Not a LOT of progress... But I guess some is better than nothing?

[GaryP]

Just keep doing what you are doing. You don't want to change it to fast. Just remember that the alkalinity level will fall a lot faster then the calcium will.

[matt]

Just a small correction on this, if I may. First, viengar neutralizes Kalk to produce calcium acetate. Calcium acetate is a lot more water soluble then Kalk so it does raise your calcium level. However, unless you add enough vinegar to completely neutralize all of the Kalk in the container the pH will still be the same as regular Kalk (~12-13). More Kalk will simply dissolve to take the place of the neutralized material.

Second, Kalk contributes both calcium and alkalinity. When you add vinegar, you no longer get the alkalinity contribution from the neutralized material, only calcium. The acetate does act as a pH buffer and as a food source but you no longer get the carbonate needed by stony corals.

Actually, Gary, I didn't say that adding vinegar lowers the ph of the kalkwasser, although the article by Rany Holmes-Farley I read on it does say that. What I did say was that adding the vinegar-spiked KW to your tank will not raise the ph as much as straight KW. That's because the vinegar-spiked KW does not remove as much CO2 from the tank.

Regarding the loss of alkalinity from adding the vinegar, that's simply not true. What happens is the acetate gets metabolized by bacteria in the aquarium and releases hydroxide ions and CO2, which then combine to form bicarbonate. (and/or carbonate as ph dictates)

Now, I don't make any claims to be a chemist, but I can read.

http://reefkeeping.com/issues/2005-01/rhf/index.php#6

[GaryP]

Matt,

Tyhanks for the link. I wasn't aware of the bacterially produced hydroxide. I was looking at it strictly from the standpoint of the chemical makeup of the Kalk solution. Interesting. When you typically think of bacterial metabolism in the aquarium, you think of them producing acids, not bases. That's why there is a downward trend in pH, and never an upward trend. I do have one problem with Randy's equation though. It assumes that the CO2 produced is chemically inert. I wish I had a way to get in contact with him. He doesn't answer his forum anymore. Anyway here goes. The equation he gave for the metabolism of acetate is:

CH3COO + 2 02 ----> 2 CO2 + H20 + OH

That seems to make sense and would make you think there is a net production of one hydroxide, right? But what about the CO2? I would suggest this is what happens as the next step in the process.

1 CO2 + OH ----> HCO3 (bicarb)

1 CO2 + H20 ----> H2CO3 (carbonic acid)

So, rather then producing one unit of hydroxide, you actually produce one unit of acid. There is actually the opposite result then what Randy predicted. Somebody please show me where I am making a mistake. Does anyone have a spare chemist in the closet that can help me out here? The overall reaction would then be:

CH3COO + 2 O2 ---> 2 CO2 + H2O + OH ---> HCO3 + H2CO3 ---> 2 HCO3 + H

Obviously there is an increase in alkalinity, but there is also a decrease in pH as a result of the production of one mole of hydrogen ion.

[hobogato]

looks right to me, but it has been 10 years since college chem class, and teaching biology doesnt require me to use this stuff very much.

[Bill S]

The problem, as Gary points out, is that what happens in a test tube, is or can be different in a biological environment. My chemistry/biochemistry is over 25 years old. That being said, I'm guessing I can try and replicate both of these tests. I've got to change some water this weekend - maybe I'll put identical 5 gallon buckets of discard water next to each other, test, and then treat one with kalk and the other with kalk + acetic acid. Now, if I had 2 identical pieces of live rock... Well, I guess I could take some from the big tank for the experiment. Guys, how much kalk & how much rock should should I put into about 3 or 4 gallons of water.

[GaryP]

Well, I drip about 2 gal. into my system that I guess has a liquid volume of around 120 gal. That works out to the equivalent of 1/2 pint into 4 gal.

[matt]

Can't answer that one. The only thing I do know from experience is that spiking KW with vinegar resulted in higher calcium and alkalinity in my old 45 breeder and in my old 10 gal nano. But, I bet if you posted that on the reef chemistry forum on RC, someone would know.

In the same article it explains how KW binds copper and phosphate. Overall I think adding KW is one of the more successful and beneficial ways of supplementing Ca and Alk. In my old tanks I just added it with a 5 gallon jug and some tubing set up as a siphon. It worked but was a constant PITA filling the jug and setting the siphon. I'm hoping using the kalk reactor and a dosing pump will make life much easier. BTW, I got my dosing pump from http://www.innovativeaquatics.com/ This guy has taken medical dosing pumps and refurbished them for aquarium use. Much cheaper than a litermeter, and it looks like it's built MUCH heavier duty.

[GaryP]

Most heavy metals like copper are insoluble at high pH. They precipitate as an insoluble metal hydroxide. Unfortunately magnesium also does this. Likewise, calcium phosphate is insoluble at higher pH. This effect usually only occurs near the point that Kalk is being added because it creates a localized area of high pH. So, if you are dripping into the sump they will often presipitate into the detritus that build up there. I occasionally use a Magnum to vacuum out my sump and remove this material.

In industrial water treating they actually add phosphates to remove calcium. Calcium phosphate is a soft, fluffy material that does not create hard scales. This is done to prevent calcium carbonate (calcite) and calcium sulfate (gypsum) scales from forming in things like boilers and cooling towers. These scales require that the industrial water systems be shut down for cleaning. Often this requires acidizing, just like we often do with vinegar, to clean pumps and other equipment.

[Bill S]

OK, so how much live rock to I add to each bucket?

[matt]

Right, I'm pretty sure the removal of copper and other metals with KW ocurrs in the make up water that's mixed into KW, not in the tank itself. So, if your salt contains copper, for example, dosing with KW will not appreciably lower that copper. But, if there's copper in the KW, it's likely that it will not be passed into your system.

[GaryP]

Yea, Randy actually does a pretty good job of explaining precipitation of metals in the link you posted. There should be very little or no metals in makeup water if you are using RO/DI. Heavy metals are not a problem in this area even in tap water unless you have a lot of copper or lead plumbing and then only when you first turn on the water. Metals can build up to low levels in plumbing that isn't flushed for a while, such as at night. Even then they are at very low levels. RO/DI water can be pretty corrosive though. Since its TDS is so low metals are pulled into solution by RO water stored in metal. Nature abhors a vacuum.

Bill, I would suggest adding LR to the test water at a ratio that is somewhere near what exists in your tank. That means if you have 100 lbs. in a 200 gal. system then I would add 2 lbs. to 4 gal. of water. For a test try to replicate the condition in the larger system as closely as possible so the test model is representative of the real world model. This also includes things like oxygenation and flow as they can have a large impact on this type of experiment.

[Richard]

I've got to change some water this weekend - maybe I'll put identical 5 gallon buckets of discard water next to each other, test, and then treat one with kalk and the other with kalk + acetic acid.


Been there, done that. I think you will find from a practical application that adding acetic acid to kalkwasser does not make much of a difference as far as being able to raise your calcium levels via kalkwasser.

Two issues with it:
First, it is simply a limitation of the volume of topoff water that you can add. Secondly, if you add enough vinegar to lower the ph of the kalkwasser so that you can add it more rapidly then what you have done is make alot more calcium acetate. The acetate will ultimately become a great carbon source for bacteria that will reduce the nutrient levels in your tank. Initially you might like the results but eventually your tank will become too nutrient poor. Then your zoanthids and softies are going to become very unhappy. If you press on anyway, eventually even even your sps will begin to fade out in the ultra low nutrient environment. It's just a matter of too much of a good thing.

I played around with kalk/vinegar for a considerable length of time years ago. Then I even tried just using lab grade calcium actetate powder (no mixing just spoon it in). Got the same results in either case...Not a great way to raise calcium levels but all nuisance algae went bye bye, then my soft corals closed up or just fell over (leathers). I think they were telling me "Hey, we gotta have something to eat!".

If you test for awhile, let me know if you get different results. Easiest thing you could do is just hook up the Ca reactor IMO.

[GaryP]

Thanks Richard.

I do use vinegar ocassionally (every couple of months) but really I only do it to clean out my Kalk drip jug. I suppose the nutrient poor situation would also apply to those folks that advocate adding vodka or any of the other low molecular weight organic compounds.

[Bill S]

Hmm. OK, so far, I've dosed the following (in about 225gallons total)

45 teaspoons of Bicarb
9 teaspoons of Washing Soda
45 teaspoons of Dow Flake

Result?

Alkalinity: from 2.5 to 3.5 or 4.0
Calcium: from 320 to 340-360

I don't seem to be making much progress?

[GaryP]

You're there on alkalinity and half way there with the calcium. The calcium is getting to the "acceptable" range. I would shoot for about 425.

[Richard]

I suppose the nutrient poor situation would also apply to those folks that advocate adding vodka or any of the other low molecular weight organic compounds.


Yes, although according RHF the people in europe that started the vodka thing say that vodka promotes different bacteria species than acetate. I've never seen any real study that identified exactly which bacteria species were responsible for nitrogen fixation and phosphate reduction so I don't know how they make the claim. I guess we are supposed to just accept that vodka bacteria are better than acetate bacteria because drinking vodka is better than drinking vinegar LOL.

[GaryP]

Well, bacteria are not that picky as to which carbon source they use. That have to be adaptable. The actual chemical difference between ethanol and acetate is almost insignificant from a microbiological standpoint.

CH3CH2OH (ethanol) vs. CH3COO (acetate).

All rapidly multiply bacteria are going to utilize available nitrogen and phosphate resources. The nitrogen is mainly used for proteins and nucleic acids (DNA & RNA) and the phosphates for making ATP (adenosine triphosphate). ATP is the molecule that organism use to store energy on a cellular level. Obviously, rapidly reproducing bacterial populations use more nutrients then do populations that are in equilibrium (reproduction equals death). I think the idea here is to create a bacterial bloom. When this happens, bacteria go into a logarthmic growth phase and their population rapidly shoots up. Some bacteria can divide every twenty minutes when there is plentiful nutrients available. That would mean that their population can increase by 8X within an hour and 64X in 2 hours. This rapid growth phase would suck the nutrients out of the water.

Obviously this sort of growth cannot be sustained without continued addition of nutrients. These nutrients would primarily consist of carbon source (ethanol, acetate, fish poop), nitrogen (ammonia, nitrate, fish poop), phosphates (ortho and meta phosphates), and oxygen.

I suppose my question is what happens after the carbon source is depleted. What happens to all thos bacteria? Some soft corals like Sarcophyton are thought to eat bacteria and I could see how that would be beneficial. My concern is that the bacterial population will crash, resulting in bacterial death and the nutrients that were used will simply be recycled back into the water as a result of decay.

BTW, I add a cap full of vinegar to my Turbo calcium dosing jug to help prevent it from reacting out with CO2 absorbed from the air. I have to clean it out occasionally because it gets nasty with bacteria growing in the jug and drip lines. I never had this problem before I started adding vinegar and it was just RO water and calcium. In that case there was no carbon source to support the bacteria. I suppose the vinegar also provides a small source of nitrogen and phosphates or my RO water isn't as pure as I thought it was. Only small amounts of phosphate are actually required. If I recall my bacterial ecology correctly, the ratio of required nitrogen to phosphurus is about 4:1.

[Bill S]

I had Richard check my water today:

Mg: 1140
Ca: 260 (I measured 220 yesterday - and have dosed about 25 teasp. of Dow Flake)
Alk: 3 meq/l

Until yesterday, I had neglected the Ca for about a week.

Richard is coming by on Tuesday to help me set up my Ca reactor.