Kalkwasser not enough?

[Reef Chem]

Hello,

I am new to the site, so hello to all and thanks in advance for any input. With that said here is my question. I have a 10 gallon mixed reef tank and I drip Kalkwasser nightly to make up for evaporated water loss. I use about 1/2 gallon of saturated solution daily. My problem is my alkalinity and calcium still drop (in two days it will drop about 20ppm calcium and a little more than 2dkh for alkalinity). According to my calculations I should be supplying more than enough Kalkwasser to the tank. The tank does not look like a "high demand" tank so I'm not sure why Kalkwasser is not enough. The only way I maintain appropriate levels is by using a 2 part supplement (B-ionic) and I use about 5ml of each per day. I know I could just keep doing what I'm doing now (Kalk and 2 part) but I noticed other people, like Randy from Reef Keeping use only Kalkwasser for supplementing their tanks. I am sure my tank does not have the demand that Randy's would have. Here are my calculations for alkalinity supplementation:
1/2 gallon of Kalkwasser per day / 10 gallon tank x 112dkh (Kalk is saturated so it should be 40meq/l which is equal to 112dkh) = 5.6dkh being added to tank daily.
My tank uses about 2dkh per day of alkalinity, so if anything my alkalinity should be going up not down.
Any help would be greatly appreciated.

Current water chemistry:
420ppm calicum
11dkh alkalinity
~1200 Magnesium
8.0-8.4 PH
77F temp
1.025 salinity

My tank has about 15lbs live rock, live sand (shallow bed), a rock anemone, clown fish, maroon clown, checkboard wrasse, scarlet crab, 4 zombie snails, green star polyps, zooanthids, brown button polyps and two mushroom corals.

[m2434]

your mg is pretty low, that is likely a big factor. Also, how are you mixing, are you certain it is saturated lime-water? Also, in a 10g, you may be raising your pH a bit high and maybe getting some precipitation that way. I think sustained pH of over 8.6, for even a few minutes can start to cause precipitation.

It dosn't sound like you have any hard coral? If so, either you have tons of coralline algae, or it has to be precipitation or measurement error. It's not uncommon not to keep up with demand in hard coral dominated tanks though.

[Reef Chem]

I agree the MG is slightly low, unfortunately I ran out of MG supplement so I am currently waiting for the shipment. The way I mix is two teaspoons in a one gallon bottle, then I use a turkey baster to mix the water (this avoids air being mixed in the solution). I have a feeling my PH is rising too high in the night when I drip as you mentioned and this is causing precipitation. Would I be better to just the B-ionic? Or maybe I should use less Kalk to avoid precipitation issues? Also, I like how the Kalk does keep the PH up, otherwise it usually falls below 8.0. Another concern with using the 2 part is I don't want to disrupt the ionic balance (long term obviously).

[tmz]

.5 gallon of fully saturated kalk for a 10g tank is about 5x what I use. A 5% evaporation rate seems way off a more normal 1% or so. Perhaps you are overdosing with precipitation which is reducing the alk.
I think the mag at 1200ppm is ok but could be a bit higher. nsw is 1280ppm.

[Reef Chem]

Thanks for the replies, it appears i'm dosing too much Kalk. I used to have a ton of precipitation (filters would clog after 2 weeks). I have been using Kent Kalk but I recently ordered Rowa Kalk. Is there something I'm doing wrong when mixing. I say this because recently I have had less of an issue with precipitation. IMO I think the precipitation problem I was having was when I was using Kent Part A & B. Now that I use B-ionic I don't notice that much of a problem with precipitation. But again, with all the kalk I added it's surprising alk would still drop w/o much precipitation showing in the tank. I guess i'm going to try 1/2 teaspoon instead of 2 teaspoon per gallon and see what happens.

[Reef Chem]

Still a little confused. So if i'm dosing too much would only the excess be precipitated out. How would it actually lower the alk and ca?

[bertoni]

The magnesium level is a tad lower than the canonical ocean average (1280 ppm), but it's fine for maintaining calcium and alkalinity, and raising it wouldn't help with alkalinity.

The kalk products should be about the same, and the only issue is how much kalk is dissolved in the water. I agree that precipitation likely is the issue.

[m2434]

It can start a chain reaction. Once suspended solids start precipitating out, they can form a seed for more to clump and precipitate out. So you can actually lower your ca and alk by raising your pH too high, instead of raise it.

[Reef Chem]

Ok, so I added two teaspoons of kalk to one gallon of water; after testing (w/ Salifert kit) I noticed the calcium is 500ppm which would make the alk 70dkh. I'm not sure why the solution is not saturated w/ two teaspoons but I can tell now that because the solution is not saturated then I was problem not dosing enough. The reason being is I probably dose closer to 1/4 gallon per day (on second thought); with that said, a 1/4 gallon per day (1.75dkh alk) would not meet the demands of my tank and that is why the alk was dropping. I think... =)

[bertoni]

I'm not sure that I'd trust the calcium test kit. You could try using an alkalinity kit, although it'll take a lot of titrant.