Kalk Question

[mindi]

I have tried several times to dose Kalk through my top up water mixing at the rate of 2 teaspoons lime /US Gallon or 3.9 litres in Aus Speak.
Each time I have found a lot of white deposited white precipitant throughout the sump... now I admit I may have a cleanliness OCD but this bugs me somewhat and I wonder if this is normal when using Kalk or whether I am making it too strong ..?

 

[bundybear1981]

How are you adding your top up water? Are you manually adding to your tank or via an auto top off?

When you mix your kalk does it all dissolve in your top off water? Or do you still have residue in the bottom of your top off container?

Once your reach saturation point you will end up with residue in your top off, if your are manually adding it this will end up in your tank.

Try to mix it until dissolved but without residue in your container. This should help to stop the white throughout your sump.

 

[mindi]

kalk

kalk

Hi Bundy...just moved south from Noosa area

Well i mix it in a 100 l bin, then after it has stood i take it off the top and decant into a topoff bin which auto pumps to the sump with a tunze osmolator....so while there is some precipitant in the mixing bin, it is not a lot....and then a little more precipitates in the top off reservoir over the 6 days it lasts...and finally more precipitant in the sump showing as white satining on the walls.

It sounds as though I have over saturated it...? my Alk is about 3.6 meq/l and Ca about 450..ph 8.3, mag maybe a little high around 1380-1400...but the fundamentals all seem OK.

Maybe this is normal for Kalk users... and I need to just get over it..?..trying to keep the sump clean as a good housekeeping thing

 

[bundybear1981]

When I mix my kalk up I use a spare power head to help mix it, usually for a few hours prior to use. I then put it in my top off drum (a 25l water drum from Bunnings) and dose using a Tunze osmolator. This feeds in to my overflow of the tank so it runs through the sump before returning to the tank.

I don't notice any residues from it.

 

[mindi]

well thats exactly what i am trying to do...what lime do you use and what amount do you mix into your 25 litres..?

 

[bundybear1981]

the one I have been using is from The Reef Shop, Kalkwasser Powder, Stringray marine filters branded (pure calcium hydroxide). Dosage at about 37.5g/25 lts of water.

 

[bundybear1981]

I mix it in to my RO/DI water (0 TDS) and agitate with a power head till its all dissolved.

 

[mindi]

Thks..will try that

 

[bundybear1981]

No worries Let me know how it goes

 

[blanden.adam]

mindi, what is your alkalinity consumption per day (measured over a week) and when did you start dosing limewater? If you are overdosing the tank (because you are dosing more than you are consuming) it can certainly cause excess precipitation in the sump. This is not specific to kalk, but will happen with any calcium and alkalinity dosing method. A little bit of precipitate where the limewater enters the sump is completely normal, nothing to worry about there.

A few notes on the comments made thus far in the thread:

There is really no need to mix the kalk for a long time. Overmixing can cause incorporation of CO2, resulting in calcium carbonate precipitation. (please note figure 3 in this article where RHF demonstrates agitating kalkwasser in an open container can completely remove its potency in a matter of hours: http://www.reefkeeping.com/issues/2005-01/rhf/). I used to give a 32 gallon brute (kalk + RO/DI) a 30 second or so mix with a length of PVC pipe, and it was more than sufficient.

With regard to the precipitate on the bottom -- there is no reason to avoid it as long as you are careful to only dose the clarified limewater on top of it. The precipitate can contain many things, but is mainly precipitated impurities and undissolved calcium hydroxide. It may even be beneficial if you are trying to dose saturated limewater, in that if your limewater loses potency over time due to calcium carbonate precipitation, there is some "extra" that can re-dissolve and take its place. It is just important to make sure your dosing pump is drawing from above the precipitate, so all you dose is the clarified limewater to your tank.

 

[mindi]

thanks for that Adam... my tank goes from about 3.6 meq/l to about 3.2 in a week.

 

[A. Grandis]

mindi, what is your alkalinity consumption per day (measured over a week) and when did you start dosing limewater? If you are overdosing the tank (because you are dosing more than you are consuming) it can certainly cause excess precipitation in the sump. This is not specific to kalk, but will happen with any calcium and alkalinity dosing method. A little bit of precipitate where the limewater enters the sump is completely normal, nothing to worry about there.

A few notes on the comments made thus far in the thread:

There is really no need to mix the kalk for a long time. Overmixing can cause incorporation of CO2, resulting in calcium carbonate precipitation. (please note figure 3 in this article where RHF demonstrates agitating kalkwasser in an open container can completely remove its potency in a matter of hours: http://www.reefkeeping.com/issues/2005-01/rhf/). I used to give a 32 gallon brute (kalk + RO/DI) a 30 second or so mix with a length of PVC pipe, and it was more than sufficient.

With regard to the precipitate on the bottom -- there is no reason to avoid it as long as you are careful to only dose the clarified limewater on top of it. The precipitate can contain many things, but is mainly precipitated impurities and undissolved calcium hydroxide. It may even be beneficial if you are trying to dose saturated limewater, in that if your limewater loses potency over time due to calcium carbonate precipitation, there is some "extra" that can re-dissolve and take its place. It is just important to make sure your dosing pump is drawing from above the precipitate, so all you dose is the clarified limewater to your tank.

That!

I add my kalk in the shark bag, placed in the sump, collecting the water from the overflow. It mixes and there is no precipitation in the sump. The kalk comes from a home made stirring reactor and it feeds the system few times a day just to keep alkalinity and to help my coralline algae to thrive. I don't like the pumps because there is absolutely no need for that much power.

In the past, when I didn't have a reactor, I used to mix kalk every night and use the crystal clear portion with a dripping apparatus. No strong mixing at all!! Just a light shake to mix the powder.
Some people just place the powder in the covered container connected to the ATO without any problems. After the calcium carbonate forms on an undisturbed surface the connection/exchange between the solution and the atmosphere doesn't count much.
I already have my reactor and it works great for me because of my available space, but like many say, it's unnecessary when you have enough room for a bigger container.

Main thing is to know how much you'll need for your system!

Grandis.

 

[mindi]

aha thanks...I wasnt getting that if you dose more than you need then you will get precipitation...regardless of Randy 2 part or Kalk...now I get it. Have to go back a step and measure alk consumption more accurately.

 

[blanden.adam]

Mindi. I did a quick calculation using this http://reef.diesyst.com/chemcalc/chem_calc3.html.

That drop in all can be compensated for using only 1% of your water volume in saturated limewater, give or take. That's more consiatant with a days top of rather than a week, so I suspect you are overdosing. I'd try using a less than saturated kalk solution, say 1/2 a teaspoon for gallon, and adjust up or down from there as necessary.

 

[mindi]

yep good..cheers