Alk keeps dropping with saturated kalk - precipitation?

puffy127 · Dec 20, 2016

I had a precipitation issue a week or so ago, but I cleaned out the whole tank, did a water change, and no longer see any precipitation, but am afraid I may still be having issues.

I have a 16g frag tank, which I dose with kalk. I have figured out that if I dose 45 ml/hr, I keep up with evaporation. It has been stable for months, with me increasing the number of teaspoons of kalk/gal to keep up with the kalk demand. I am now up to full saturation 2 tsp/gal of kalk, but this does not seem to keep up. This is about 2 dkh per day from the kalk and I still drop 1 dkh per day. I only have about 8 one-inch acro frags in there, so it doesn't seem like it should be consuming as much as it does (~ 3dkh consumption). Magnesium is at 1390 ppm. Calcium is at 425 ppm. Am I still having precipitation problems or is it just that my frags are consuming that much alk?

Elementalj · Dec 20, 2016

puffy127 said:
I had a precipitation issue a week or so ago, but I cleaned out the whole tank, did a water change, and no longer see any precipitation, but am afraid I may still be having issues.

I have a 16g frag tank, which I dose with kalk. I have figured out that if I dose 45 ml/hr, I keep up with evaporation. It has been stable for months, with me increasing the number of teaspoons of kalk/gal to keep up with the kalk demand. I am now up to full saturation 2 tsp/gal of kalk, but this does not seem to keep up. This is about 2 dkh per day from the kalk and I still drop 1 dkh per day. I only have about 8 one-inch acro frags in there, so it doesn't seem like it should be consuming as much as it does (~ 3dkh consumption). Magnesium is at 1390 ppm. Calcium is at 425 ppm. Am I still having precipitation problems or is it just that my frags are consuming that much alk?

Do you see the precipitation? Are things dusty looking?

Randy Holmes-Farley · Dec 21, 2016

puffy127 said:
I had a precipitation issue a week or so ago, but I cleaned out the whole tank, did a water change, and no longer see any precipitation, but am afraid I may still be having issues.

I have a 16g frag tank, which I dose with kalk. I have figured out that if I dose 45 ml/hr, I keep up with evaporation. It has been stable for months, with me increasing the number of teaspoons of kalk/gal to keep up with the kalk demand. I am now up to full saturation 2 tsp/gal of kalk, but this does not seem to keep up. This is about 2 dkh per day from the kalk and I still drop 1 dkh per day. I only have about 8 one-inch acro frags in there, so it doesn't seem like it should be consuming as much as it does (~ 3dkh consumption). Magnesium is at 1390 ppm. Calcium is at 425 ppm. Am I still having precipitation problems or is it just that my frags are consuming that much alk?

That's isn't obviously too high, but how high was it just before the event?

puffy127 · Dec 21, 2016

I had to keep upping the dosage over the last few weeks prior to me realizing it was due to precipitate and not actual consumption from the corals. I turned off the doser last night, increased the alk to 8.6 using baking soda and tested again tonight, 24 hours later. Without any dosing, the alk only dropped down to 7.9, so a decrease of 0.7. Is that my true alk consumption? What should be my next steps? Should I reduce my dosing to 15 ml/hr (which should work of to .67 dkh per day)? Or keep the doser off another 24 hours and see what happens?

Randy Holmes-Farley · Dec 22, 2016

puffy127 said:
I had to keep upping the dosage over the last few weeks prior to me realizing it was due to precipitate and not actual consumption from the corals. I turned off the doser last night, increased the alk to 8.6 using baking soda and tested again tonight, 24 hours later. Without any dosing, the alk only dropped down to 7.9, so a decrease of 0.7. Is that my true alk consumption? What should be my next steps? Should I reduce my dosing to 15 ml/hr (which should work of to .67 dkh per day)? Or keep the doser off another 24 hours and see what happens?

Not sure what you mean true alk consumption. Is it all from corals? Doubt it. There is always precipitation. :)

You can try dosing that amount and see what happens. Demand rises as pH and alk rise. :)