Top off problem and weird white buildup on glass

[Dave VG]

I use Kalkwasser in my RO water for my top off and I had a problem with the float sticking off yesterday leaving my return section about a half or more gallons short of being full and the pump sucking some air but not running completely dry. So I cleaned the float valve up and let it run afterwards to top it off. This morning I woke up to a white film on the glass like the kalk has built up on it. What the heck. Is this common if to much Kalkwasser is introduced like this? Very hard to scrape off I might add.

 

[Capt_Cully]

Depending on your parameter readings, dKH/Alk, Ca, Mg, you might have reached a saturation level causing the calcium to precipitate out of solution into a solid form. That might be what you're witnessing. You'll need to check your parameters before moving forward.

 

[jacksonpt]

yes, it is... I stopped using kalk for this very reason. if/when I'm able to get my params more consistent, I may go back to it... but for now that white residue/precipitate/whatever it is is more of a headache than its worth.

 

[Dave VG]

jackson I’m beginning to feel that way to. My parameters were pretty consistent before starting the kalk and still seem to be I thought any way. So if my tank were at its saturation level with kalk which is what its sounding like wouldn’t my calcium level be way high and the PH and ALK be out as well?

 

[tmz]

Likely, when you refilled the top off , the flow of new water stirred up the lime ( aka kalk, calcium hydroxide) dosing some cloudy water including undissolved calcium hydroxide . This in effect overdosed too much kalk at one time leading to a spike in ph and alk causing calcium carbonate precipitation. When the precipitation occurs it reduces the solute calcium and carbonate down to the levels the water can hold in solution so it would not show up in increased alk and kalk after the precipitatin event.

IME andIMO, top off and auto stirring arrangements tend to run into this difficulty. Still reservoirs where only the clear water is dosed provide a more consistent dose. Allowing kalk to settle out for 2 hours or so after each stirring and insuring the dosing intake tube is several inches above the bottom of the reservoir obviates this problem since only clear water is dosed.

 

[Gary Majchrzak]

I agree the white substance sounds like precip.

FWIW I've abused kalkwasser probably more than everybody else on this forum combined and I've never had a white precip form on glass because of a milky overdose (or otherwise).

 

[Dave VG]

Thanks for all the great info guys and yes some white water did get into the tank while I was cleaning the float off Tom so there you have it. Oh well chalk this up to another learning experience. Next time I will take the float out to clean it.

 

[tmz]

Early on as in years ago I made my share of mistakes as well. I recall on one really bad overdose some precip on the glass. It is tough to scrape . If it were bacteria it would scrape easy.

 

[tmz]

BTW an overdose of carbonate as in two part supplements can also cause abiotic precipitation of calcium carbonate,the same stuff that precipitates when kalk is overdosed.

 

[Dave VG]

Thanks Tom I'm beginning to question my test kits accuracy

 

[tmz]

Don't know what test kits you are using but during or after a cloudy dose some undissolved kalk in the sample could easily throw off any kit.