Another Kalk drip question with a twist

[Drouse]

Randy et al.,

I am fine tuning my CA reactor, but my Ca levels have actually dropped from 410, with 50 ml of Kent Tech A and B in am and 1 gallon of Kalk evap top-off at night, to 325 with Kalk only and reactor. Effluent ph is now 6.95. Haven't checked the effluent CA or Alk today.

I am scrambling to raise the Ca level by supplementation by dripping 1 gallon Kalk at night after the lights go out and 1 gallon in the am before work. I am only able to drip 1 gallon at a time due to the container volume and evaporation rate. I add 2 teaspoons of Mrs. Wages Pickling Lime mix it up and let it sit for appr. 8 hours before dripping. I drip it quite fast, almost an interrupted stream, without a ph rising above 8.4. My tank volume is a 150 with a 30 gallon sump. Alk is 4.65 KH and Mg is 1246. Ph before lights on is 7.96 and prior to lights out 8.25.

My question is if I remove tank water say 5 gallons, saturate it with Kalk, let it precipitate and re add it back into the tank at a controlled rate , not spiking the ph over 8.4 would that through the ionic balance out of whack?

Thanks

Dave

[Randy Holmes-Farley]

Alk is 4.65 KH

Either the units are wrong, and the alkalinity is 4.65 meq/L (very high, IMO) or the units are dKH, and the alkalinity is very low. We'd have to know this before prescribing a solution to your problem.


My question is if I remove tank water say 5 gallons, saturate it with Kalk, let it precipitate and re add it back into the tank at a controlled rate , not spiking the ph over 8.4 would that through the ionic balance out of whack?

No, that would be very bad. You'll take much of the calcium and alkalinity out of the solution that way. In a sense it would be like letting the whole tank rise in pH to 9 or more, getting a huge CaCO3 precipitation event, and then using the water that remained: it likely will be deficient in both calcium and alkalinity.

I know it seems counterintuitive that adding calcium and alkalinity can reduce calcium and alkalinity, but it is true. Seawater (and salt mix water) is substantially supersaturated with calcium and carbonate. If you push the limits and cause a big precipitation event, you may take it all the way back to saturation, which is well below where the salt mix starts out.

[Drouse]

It was 4.65 meq/l, wrong units. The alkalinity has climbed since to "off the chart". I slowed the bpm down and maintained the flow rate. Last night the alkalinity was measurable at 14.6 KH and Ca was up from 385 to 410. Mg 1300, ph effluent 7.10. I have been using Kalk and on Sat. started adding calcium chloride (Kent's liquid CA) 25 ml every morning.

Did the same morning ritual today, ph was 8.00 although now my wife called me at work in a panic saying the tank was white. I assumed a precipitate was forming from something. She tentatively measured the CA at 420.

Why the precipitate now?

[Randy Holmes-Farley]

Why the precipitate now?

I'm not sure exactly what's taken place between the "then" when there was none, and "now" when there is some precipitate.

If the alkalinity was high, that would help cause a precipitation event.

A trigger might be some limewater being added, or something else that is high in pH.

FWIW, I've had these events a few times and I never had any lasting consequences.

[Drouse]

I appreciate the response and I let out a sigh of relief with your last statement.

Thanks

Dave