Well, confused again.....

[j0tca]

Hi,

I haven't paid much attention to my Ca or Alk levels in recent months for various reasons, the most of which being I had little SPS.

I decided that I would bring my Alk and Ca to within good parameters this week and this is the scenario:

1) Original Ca = 225, Alk = 3.4 meq/l

Add 200 g or so of Anhydrous CaCl2

2) Ca = 325, alk= 2.85 meq/l

Add 100 g or so Cacl2

3) Ca = 400, alk = 2.76

This is over a 72 hour period.

At this point I thought I ws close enough to resume my kalk reactor to bring myself within a good area of Ca/Alk. My aim is for Ca 425, Alk 3.4 meq/l

So I used kalk for top off, and got

Ca = 400, alk = 2.5 meq/l

I thought it strange for my Alk to drop and not my Ca, especially after adding limewater.

Tonight I monitored the Kalk addition more carefully and thus

before: Ca = 400, Alk = 2.57 meq/l

after: Ca = 400, Alk = 2.00 meq/l

I'm confused.

Why is my carbonate/bicarbonate level dropping compared to my Ca level with the addition of limewater? Shouldn't they both raise together? or at least drop together? The Alk and Ca levels remain essentially the same if I make no changes, but if I add limewater, my Alk drops.

Can someone explain this to me?

 

[Randy Holmes-Farley]

The drop from 2.57 meq/L to 2 meq/L would only cause a 11 ppm drop in calcium, and I expect the noise and inaccuracy in the calcium testing is higher than that. So I would not try to interpret such small changes.

 

[j0tca]

Good point.

I also recognize that the balanced Alkalinity with a Ca of 400 is about 2.0 meq/l. Is my water supersaturated so that all addition is eating up Alk until it reaches a better balance?

Why aren't my levels rising with the limewater addition?

Thanks for the help,
Will

 

[Randy Holmes-Farley]

Forget the "balanced" part, and target the alkalinity to be 2.5-4 meq/L regardless of the calcium level.

As pH rises, demand rises, so if the limewater raises pH, it can actually cause calcium and especially alkalinity levels to drop a bit. Try adding more limewater, or a two part in addition to the limewater.

How high is the pH getting?

 

[j0tca]

My ptank Ph seemed to have dropped to about 8.10. Unfortunatley I tried to recalibrate my Ph meter and noticed that the buffered solutions I was using to recalibrte were boviously ruined somehow. My lfs was out of calibration solution so until tuesday I'm not going to be able to monitor ph. I'm continuin with my limewater topoff and I'll mesure the ph once I recalibrate.

I don;t think there was a Ph raise witht he limewater addition. I have been constaly using a kalk reactor for over 6 months with a very low Ca level. My tank is used to the constnat high Ph addition and used to run at about 8.35.

 

[Randy Holmes-Farley]

OK, lets see what the pH is when you can get some calibration solutions. The amount of CO2 in your home air will drive the tank pH, and in Montreal in the winter, I'd expect a lot more indoor CO2 (lower pH) than in the summer and fall.

 

[j0tca]

Very interesting note about my location. You're right of course. My building is air heted which means the air itself is recirculated probably resulting in a much higher concentration of CO2. I'm almost tempted to have a friend at a lab test it to see the difference.

I'll let you know the Ph once I find it.

Thanks for the help

 

[Randy Holmes-Farley]

You're welcome.

Good luck.