Kalk causing skim...

[footbag]

Since I began adding kalk to my top off water, I have developed a skim on the surface of my display and fuge. I belive that the skim from the kalk got sucked up during an "I forgot to unplug the topoff" incident.
Is the skim from kalk really bad?
I am going to add another powerhead to hit the surface, but am at 15x turnover with my current ones. Seems like all of the growth has slowed the water movement.

 

[dburr]

Does it look crusty? If it does, yes it's kalk.
Is the skim from kalk really bad?
Well, it's not real bad if you got some in the tank. I wouldn't let it keep happening all the time though. Bang or someone mentioned their could be stuff like heavy metals and other stuff in it. Not 100% sure. Can you take a net and skim the crap out? The scum will keep the tank from haveing gas exchange alittle. A PH will help alot.
Good luck.

 

[blk822]

Kalk can precipitate phos. from top off water so if you let the actuall white stuff get in your tank you may be adding phos.

 

[thomas712]

Originally posted by footbag
Is the skim from kalk really bad?

The film on the surface is pure Calcium carbonate that has formed on contact with CO2, its not the worst stuff in the world but it is recommneded to keep it from entering your system. I use a 1 gallon juice jug that I siliconed some airline tubing to with a drip valve. The top of the jug has a screw on top. This top is tightend and then just bearly loosened so that some air gets in while it drips. This cuts down on the film at the top. Also using vinegar to mix your kalk greatly reduces this film.
If you need to know more about vinegar let me know.
Thomas

 

[bang guy]

Like everyone said, it's not a terrible thing to have happen once in a while. The pure Calcium carbonate crystals will begin a reaction with the Calcium and Carbonate in your tank and pull a little bit out of solution. Magnesium stops this reaction so you also loose a little bit of Magnesium.
Also noted above, if there are any impurities in the Kalk powder they tend to collect on the bottom and in the surface film. This isn't much of a problem with the commercial brands but it could be if you use Pickling Lime or Agricultural Hydrated Lime like I do.
Bang

 

[footbag]

Thanks, it only happens about once a month. I won't be so woried, but am going to get a larger topoff bucket. 4 gal wont do anymore.