How much Limewater at a time?

[AZBigJohn]

I have started using Mrs. Wages Pickling Lime in my top-off water in my larger tank (55 gallons with a 30-gallon fuge) and it is holding everything steady.

My question is, I also have a 24 gallon bullet-shaped tank that I am starting to see calcium and alkalinity drops in that water changes alone are not maintaining. I do not have an auto top-off system on that tank (and doubt my wife would tolerate one in the living room) so I just add RODI water to the tank to keep it level every day or so.

My question is, can I add some of the limewater to my top off to help with maintaining the alk and ca? If so, how much at a time? I do not want to dramatically raise the alk or ca, or cause precepitation?

Any rough guesses as to the amount of limewater I could safely add to roughly 23-24 gallons of water at one time without causing too dramatic a shift in those parameters?

[hedgedrew]

2 tsp per gallon in your vat and drip or add over course of day equal to your daily evaporation. Any more and you change salinity. Its better for maintenence than to add calcium and alk.

[blanden.adam]

You really shouldn't add kalk "at one time" as in any significant quantity you could cause a huge pH spike, resulting in calcium carbonate precipitation, unstable alk, and general unpleasantness with the potential of tank crashing. You can replace 100% of the makeup water with saturated limewater and be OK, the trick is making it drip sufficiently slow. As an example, if you were to replace 1.25% of the aquarium volume with saturated limwater (a reasonable estimate for daily topoff) all at once, you would increase the ph of the tank by about 0.7 units! I think we can all agree that that is wayyy too much. A good rule of thumb is to not dose more than 1/4 a tsp of kalk per hour per 50 gallons or so (in limewater equivalents of course).

In your situation, I'd either talk my wife into letting me build an ATO system and hide the bin (2 things that I've done are a 5 gallon bucket and a maxijet or some other pump hidden inside an ottoman, and the other is a 32 gallon brute in the basement with a line run through a 1/4" hole in the floor, both hidden nicely.) Or a DIY kalk dripper:

http://www.reefkeeping.com/issues/skip/agu/kalkdripper.htm

Mix up the kalk in the morning, let the slurry settle during the day, and then drip the kalk all night.

For more details please see this article by Dr. Randy Holmes-Farley:
http://reefkeeping.com/issues/2005-01/rhf/index.htm

Also, start slow with kalk, maybe with just 1/2 to 1 tsp/gal of topoff water, do that for a few days, and then test your alkalinity and adjust from there. Use the alkalinity as your guide as it is way more sensitive to small changes than calcium, for a number of reasons that are outside the scope of your question, so I wont go into them :)

Good luck!

[bertoni]

Limewater is most easily dosed as ATO from a peristaltic pump, in my opinion. As has been stated, adding a significant amount in one shot can spike the pH. Here's a quote from Randy:

Adding 1.25% of the total tank volume with saturated kalk water will boost pH by an unacceptable 0.6 to 0.7 pH units and add about 1.4 dKH.