Keeping up Ca, Mg and str.

[Ace25]

Well, what I take away from all this is I have been being overly concerned about precipitates/crust forming on the surface. I thought it did much more harm by reducing effectiveness but it seems I was wrong.

Back to the original problem, still curious to find an answer to why your water is still cloudy. I have never seen that reaction with kalk and I have been using it for close to 10 years now. It has always cleared up for me within 24 hours. I am really out of ideas, and I have been racking my brain all day trying to think of what could cause that issue.

Or have you moved on and just dumped out the first batch and onto the second (which is what I would have done by now).

[Floyd R Turbo]

Actually I just checked it, and it is pretty much clear. The diluted batch is almost perfectly clear, and what's left of the saturated solution is clear also if I blow on the surface to move the wax layer away. I wonder why it took so long. I still have to test the diluted batch.

[reefdiy]

Well, what I take away from all this is I have been being overly concerned about precipitates/crust forming on the surface. I thought it did much more harm by reducing effectiveness but it seems I was wrong.

Exactly! Especially when using vinegar in the solution.

still curious to find an answer to why your water is still cloudy.

I am no chemist but I know a little bit (just enough to crack off in forums...lol) and I have a few ideas (from my perspective):

From what I can tell any cloudiness, whatsoever, is an indication of one of two things. It is either a simple over saturation of the solution or a precipitate was formed that is clouding up the water.

1) First off, by over saturated I mean that there was simply more kalk (powder) added than was considered soluble for the volume of water. Therefore the remaining kalk powder was "left behind" because it did not take part in the chemical reaction and is therefore either left suspended in the fluid or settles to the bottom. I don't think this was your problem floyd as you added the correct amount of kalk that is considered soluable in pure water, depending on the temperature (we will talk about this in a bit).

I mixed 5ml per quart, or 100 mL in 5 gallons, then 10 tsp in the water.

2) The second option is that a precipitate was formed. This is maybe the more likely answer (unless temperature was the issue with reason one - getting there).

But I guess I should have mixed the 100ml vinegar with the kalk first, then added the water.

This in my opinion would definitely have an effect on the formation of precipitate (ie. carbonate, instead of bicarbonate) because the solution would not have had the opportunity to fully react with enough CO2 to stoichiometrically saturate the solution with CO2 producing only bicarbonate in the vinegar mix before being diluted into the water. Also the amount of vinegar used was quite low (for the volume of water) thus creating a situation by which more CO2 was available than normal ro/di water, but not enough. Still allowing precipitate to form.

Interestingly, there are some who have experimented with tap water for use in mixing up batches of kalkwasser (this is not recommended). What some of them found was that the tap kalk cleared up in 2-3 hours, while the ro/di kalk never cleared up, remaining cloudy. Tapwater already contains Calcium and alkalinity salts, plus lots more. The RO membrane stripes the water clean of all these things, essentially making more "room" for anything to dissolve. I can not really understand and/or comment on these findings as it hard believe or comprehend why tap water might seemingly work "better" (dissolve more/precipitate less). It certainly seems like less would dissolve in tap water than in ro/di water. The only thing that I see that could be happening is that the tap water used had a high concentration of dissolved CO2 and therefore allowed for less precipitate. Just thought I would add this for curiosities sake.

Ok, now to the temperature question. Temperature definitely has a part to play in this reaction. How much this has effected your solution depends on a few variables and to be honest I am unsure. By this I mean that a saturated solution occurs at 25 degrees C (77 degrees F), at a calcium concentration of about 800 parts-per-million. Whether being off by one or 2 degrees C would have an effect on the solubility of kalk in water, I can not comment but it is interesting to speculate. If this is correct then maybe the temperature of the room is not allowing all the kalk to dissolve in the water as in possibility #1.

Here is some interesting information on temperature and solubility:

Effect of Temperature on Solubility:

The solubility of solutes is dependent on temperature. When a solid dissolves in a liquid, a change in the physical state of the solid analogous to melting takes place. Heat is required to break the bonds holding the molecules in the solid together. At the same time, heat is given off during the formation of new solute -- solvent bonds.

CASE I: Decrease in solubility with temperature:

If the heat given off in the dissolving process is greater than the heat required to break apart the solid, the net dissolving reaction is exothermic (energy given off). The addition of more heat (increases temperature) inhibits the dissolving reaction since excess heat is already being produced by the reaction. This situation is not very common where an increase in temperature produces a decrease in solubility.

CASE II: Increase in solubility with temperature:

If the heat given off in the dissolving reaction is less than the heat required to break apart the solid, the net dissolving reaction is endothermic (energy required). The addition of more heat facilitates the dissolving reaction by providing energy to break bonds in the solid. This is the most common situation where an increase in temperature produces an increase in solubility for solids.

It would be a very interesting experiment to CO2 saturate kalk in vinegar and then add that solution to volume of water smaller than what is considered volumetrically soluble at room temperature, but that is heated up, and see if you could super saturate the water with CO2 saturated kalk to achieve a super saturated source of bicarbonate. I am not recommending this to anyone as I do not know the outcome and I am unsure of the possibly disastrous results. If you do try it, please take safety precautions.

A safer form of this experiment would be to use "mildly warm" water to mix the Kalkwasser or using less kalk per gallon/liter when using cold water (as ro/di water is usually pretty cold). This would have the result of allowing all the kalk to dissolve to a greater extent but would not reduce precipitate. Only CO@ saturation by vinegar mixing can reduce precipitates.

As far as dosing this cloudy kalk mix there are two opinions:
1) 100% safe, dose to your hearts content.
2)Dosing cloudy water is potetnialy harmful as it may contain precipitated impurities and more importantly undissolved calcium hydroxide which can lead to an overdose.

I take neither stance because I dose completely clear, CO2 saturated and 100% dissolved kalkwasser!

In conclusion,
1) Temperature affects solubility (not something most people think about)
2) Kalk has two important characteristics: It needs to be fully dissolved into a liquid (just like any other solid) and It requires CO2 saturation in order for it not to precipitate carbonate (unique to kalk).
3) A completely clear kalk solution is the ideal, as it is fully dissolved and has no precipitate. This is the most efficient solution one can attain. It is the most effeciant because no kalk powder is going to waste by being precipitate out or by being undissolved. This allows for no waste of kalk and for an effective distribution of bicarbonate to the reef aquarium (a cloudy solution will still work, but will be less efficient and less effective).

for your consideration.....
-Ben

[reefdiy]

For more mind bending read this article by Randy Holmes-Farley: http://www.reefkeeping.com/issues/20...hf/index.php#7

The sections on limewater are especially of interest to this thread...

-Precipitates on Top of Limewater
-Precipitates on Limewater Drip Tips
-Precipitates on the Bottom of Limewater Reservoirs
-Precipitates in Limewater Delivery Tubing
-Precipitates from Overdosing Limewater

For your consideration....
-Ben

[kotlec]

Can anyone explain why I am having big trouble keeping alk on par. My 16g is heavy loaded with corals . Especially SPS are expanding at enormous rates. I understand that thats why I need take care about ca+alk very much. Started dosing Randy's DYI 2 part , because of that. It was hard too maintain calcium before. Now calcium is stable with constant dosing amount. But alk is dropping whatever I do. It even seems to me , that more I add alk part , the more it is dropping. Theory says I need equal proportion of both parts to go. I already dose 2x of alk and still alk is dropping very fast . Mg interestingly is slowly raising by itself. Now nearly 1500. I use lab grade chemicals that has certificates of quality. Claims 99.5% purity both.
All Salifert tests used.
Coraline has hard time to grow.
Any ideas ?

[SantaMonica]

The scrubber is using the alk.

[kotlec]

Thanks for reply.
Hope it is so. Good to know.

[Floyd R Turbo]

Well I started with a mixture of saturated BRS Kalk diluted to 30% strength. I put it on the tank on Friday but the air line got pinched and it didn't dose at all (I had added some of the old BRS solution and cleaned the strainer in the tank, so it didn't miss out on much). Yesterday when I figured out what happened I got it running and it dosed about a gallon of the mix. Then I check today and it had sucked down about 1.5 to 2 gallons more. I checked Alk and it has dropped from about 7.5-7.7 to about 6.7! Cal has also dropped a bit (but it hadn't dropped for a week) down to about 415. I'm thinking that I need to up the strength a bit, so the next bucket will be a 50% solution.

Also I recall hearing that you either shouldn't or can't use Kalkwasser to raise/adjust alk. Is this true? It seems like you would be able to do it...curious for clarification

[Ace25]

The only reason you wouldn't want to use Kalk to raise Alkalinity is if you have good/high Calcium readings, since Kalk raises both in correct ratios. Say you had Alk of 5.0 and CA of 500 then dosing Kalk would not be a good idea, just dosing Alk suppliment/buffer would be the correct choice. If you had Alk at 5.0 and Ca at 280, then Kalk is the perfect tool to use to raise both.

Please be VERY careful with what you believe your seeing on your test. Do not do anything fast or try and fix a perceived issue, because chances are what your seeing is not true. I have been down this road myself and just recently a good friend of mine has as well. When my tank crashed hard I was seeing the same thing, I would dose Alk or Kalk and the next day my Alk would be LOWER than the day before. The problem for my friend and I had nothing to do with Alk, everything to do with other factors (mine was CO2 related, his was a bad ORP probe on his ACIII controller that gave his pH probe false readings plus a faulty Alk test kit).

I am not sure the issue with every tank, but anytime I see someone dose Alk or Kalk and come back the next day stating their Alk went down, I now always say "slow down, really think things though, figure out the problem, and whatever you do, DO NOT dose any Alk buffer and do not up your Kalk dosage, just let it sit for a few days and use your eyes to tell you how your tank is doing, not a test kit or a probe. Ask lots of question online, get lots of input to think about before even thinking of taking steps to try and correct it". If your tank looks happy to your eyes, chances are it is happy, even if test kits are telling you otherwise.

[Floyd R Turbo]

I hear you there. What I found strange is that I tested my BRS mixture and Kalk mixture for pH and Alk (although I'm not 100% sure the Alk between the two is "the same") and they were reasonably close to each other. So what I expected to see was the alk at least stay the same, or drop at the same rate. On that note I have to mention that the BRS Alk mixture was not maintaining the alk at 9.0 where I like it, it had been steadily dropping to where it currently is. It seems that the alk tends to drop in surges, and I'm not sure this is in relation to the scrubber growth or cleaning cycle, etc. Calcium also tends to drop in surges. For instance, one week I will correct it with BRS cal to say 440, then a week later, it's still around 420. I will correct it to 425-430, and a week later it will drop down to 380. So maybe I caught it on the uptake swing of one of these cycles.

Well I have a full 5g bucket of 30% mix so I will just use the rest of that up and test daily to see if I can figure out what is going on. I'm wondering if it's possible that Kalk is a 'better' version of dosing, and thus the corals are utilizing it better, which would explain how I matched the BRS mixture yet still had a drop in levels.

But the true words you spoke are "how does the tank look". If it ain't broke, don't fix it. So for now, I will monitor and make only small gradual adjustments and let the tank decide if there's something else going on.