Kalkwasser or two part for me?

Randy Holmes-Farley · Oct 10, 2015

Ryan15236 said:
Ok so test alkalinity over a weeks time or so and see the rate of depletion. Figure out potency needed? Maybe start with 2tsp for the whole 8 gallons. Then maybe put a lid upside down and sit the ATO pump in it so doesn't suck anything straight from the bottom. Then I guess just monitor pH, alkalinity, and calcium. Clean reservoir when needed? About it?

I'd pick a potency (2 tsp per 8 gallons seems fine) and then monitor alk over time to raise or lower the potency, rather than predicting from none.

Demand for calcium and alkalinity depends on both the pH and the alkalinity, so allowing it to change from normal gives a skewed recommendation.

Just putting the ATO inlet a bit above the bottom serves well enough to keep solids from entering.

Ryan15236 · Oct 10, 2015

Thanks Randy you have been super helpful with this and I feel like I have an understanding and prepared for this. Only other thing I am worried about is my pH already being 8.4 and my understanding is limewater has a pH in excess of 12.o. Will this raise my pH too high?

Randy Holmes-Farley · Oct 10, 2015

pH 8.4 is the peak?

Limewater will raise pH, but I had a tank that ran for years at a peak of 8.55 without issue. The only concern seems to be that precipitation on pumps and such may be faster. I think many calcifying corals may actually like higher pH because it is easier for them to pump out H+, which is a byproduct of calcification.

But, more aeration will bring it down if pH gets too high.

Ryan15236 · Oct 10, 2015

I got 8.4-8.3 on an API test this morning when the actinics were on. Maybe I need to look into a more precise pH test but that is what I got this morning. I will test again tonight at the end of the lighting cycle.

Randy Holmes-Farley · Oct 10, 2015

Ryan15236 said:
I got 8.4-8.3 on an API test this morning when the actinics were on. Maybe I need to look into a more precise pH test but that is what I got this morning. I will test again tonight at the end of the lighting cycle.

I'd be surprised in the pH hit 8.3-8.4 in the AM in the absence of using very high pH additives.

Ryan15236 · Oct 10, 2015

Yeah I know. I am not adding anything to the tank. I think I added like 18 mls of the sodium bicarbonate solution last weekend for alkalinity but that is it. What do you use to test pH?

Ryan15236 · Oct 10, 2015

I just retested it with two different high range api reagents. One read 7.8 and one read 8.0...this sounds much more reasonable. I made sure I just inverted the test tubes and not too shake it. I will test again at the end of the lighting cycle but I would say I have a max pH around 8.0-8.1

Randy Holmes-Farley · Oct 10, 2015

OK, so you won't have a pH issue with the limewater.

Randy Holmes-Farley · Oct 10, 2015

Ryan15236 said:
Yeah I know. I am not adding anything to the tank. I think I added like 18 mls of the sodium bicarbonate solution last weekend for alkalinity but that is it. What do you use to test pH?

A pH meter is a better bet than most kits because you check the for accuracy when you calibrate them. good enough. Any meter with two point calibration is adequate.

Ryan15236 · Oct 10, 2015

Thanks for your time! I may get back on this thread in about a week after I have the calcium carbonate in the ATO and monitor the alk and let you know how it's going

Randy Holmes-Farley · Oct 10, 2015

You're welcome.

I presume the "calcium carbonate" in a typo, should be calcium hydroxide.

We'll look forward to hearing the results.

Ryan15236 · Oct 10, 2015

Haha yes my bad the calcium hydroxide! You don't miss a beat lol

Randy Holmes-Farley · Oct 10, 2015

Good luck!

black_art · Oct 20, 2015

Dear Randy,
I am from Iran. In here we have a type of Lime which has 96% CaCO3 and 4% SiO2+Fe2O3+Al2O3. I was wondering whether I can use it in our reef tank by mixing with RO water and adding to tank in order to increase our Kh and Cl.

Randy Holmes-Farley · Oct 20, 2015

No, that wouldn't be suitable, assuming that is the true chemical analysis and not some sort of regulatory regulation to show the calcium content and not the actual calcium chemical form . It needs to be Ca(OH)2 (calcium hydroxide).

The name is confusing as "lime" seems to be applied to both calcium carbonate (which is what you have) and calcium hydroxide.

saleen385 · Oct 20, 2015

not to hijack,
but if I'm understanding this you don't want to keep the kalk stirred up in the ATO

jim

Perculap · Oct 20, 2015

Randy Holmes-Farley said:
I reuse it each time as I rarely clean the reservoir. It's been a few years now.

I actually add more than needed, then stir a few minutes while monitoring conductivity to ensure I have adequate potency.

Randy, when you fill up your ATO reservoir doesn't the settled stuff on the bottom get mix up? Does that settled stuff then dissolve during refill in addition to the new kalk being added? Or is it not a concern? (I've abandoned kalk and just dose 2 part manually.)

Randy Holmes-Farley · Oct 20, 2015

The solids on the bottom of a limewater reservoir contain many things. One that can dissolve is excess calcium hydroxide which can just be reused in the next batch. There's no harm in having excess around, unless you are aiming for a low potency level.

Other things settled to the bottom include calcium carbonate and magnesium hydroxide, which will not dissolve and even if stirred up will just resettle. Other impurities will also settle out or bind to the surfaces of these others.

In generql, I don't worry about these solids as long as they remain in the reservoir and I've not cleaned out my reservoir and the thick mud in it for several years.

Randy Holmes-Farley · Oct 20, 2015

saleen385 said:
not to hijack,
but if I'm understanding this you don't want to keep the kalk stirred up in the ATO

jim

That's correct, if it is a batch type of reservoir. I only stir mine for a few minutes, then use it over the course of a month.

But if it is a continuous refilling system, such as a small volume reactor, it will require more frequent stirring, but should be more carefully protected from air.

ultimatemj · Oct 20, 2015

Good info Randy,

I'm curious, is there a visual way to distinguish between settled calcium hydroxide and calcium carbonate?
Or is there a rule of thumb for how much calcium carbonate you should expect?

I ask because I'm running kalk via my 3g ATO, which has it's own ATO (Avast barrel tender) that refills it with RODI when it gets down to 1/3g. I add about a TBL of lime once or twice a month, with the expectation that the ATO being refilled will stir it up and dissolve the "extra". Well, the amount of "mud" seems to be growing faster than I expected...I can't tell if I need to be stirring it up, or be prepared to clean it out every 6months.

Thanks for the insights!