Exceeding the limewater evaporation limit

[Garf]

Mind blown.
Got to the 90DKH solution before it was all dripped into the tank.
A few calcium crystals added, dissolved in 1 pint(ish)


1/3 teaspoon added, dissolved after quick stir;


I’ll keep hold of this and see if it’s stable.

pH of resulting solution is 8.05ish
pH of startup saltwater is 8ish

Result after checking salinity of solution to make sure I’m not going mad. Near the 1.030 mark. I would like someone to replicate if possible.

 

[Randy Holmes-Farley]

I mean to add calcium carbonate.

 

[Garf]

I mean to add calcium carbonate.

I thought calcium chloride and bicarbonate would be a no no in saltwater. I don’t want it to precipitate, I want to exceed the limewater evaporation limit, lol

 

[Randy Holmes-Farley]

I thought calcium chloride and bicarbonate would be a no no in saltwater. I don’t want it to precipitate, I want to exceed the limewater evaporation limit, lol

To have the same effect on precipitation as a 0.3 ph unit rise, one would need to double alk from 7 to 14 or calcium from 430 to 840.

Thus, in a normal reefing scenario, pH is often the biggest driver (8.5 is often attained), followed by alk (alk of 14 dKH is fairly uncommon), with calcium rises a distant third (800+ ppm calcium is very rare.

Calcium carbante solids will great speed the precipitation. Phosphate, organics (some of them) and magnesium deter it.

 

[Garf]

As far as I can tell through dilution of samples and tested with Salifert, the glass of saltwater I’m watching for any sign of precipitation has 90DKH and 2500 ppm calcium. Nothing dropping out yet. Hence my confusion.

 

[Garf]

For what it’s worth i can dissolve 3 teaspoon of bicarbonate per liter without issue. Dunno what that works out to, but it’s a lot. Adding 1.5 teaspoon of calcium chloride and 1.5 teaspoon of bicarbonate in 1 liter causes a slow precipitation. Appears 1 teaspoon of each, calcium and bicarbonate per liter does not precipitate. Mixed 50% of this solution with tank water, still nothing falling out.

 

[Randy Holmes-Farley]

For what it’s worth i can dissolve 3 teaspoon of bicarbonate per liter without issue. Dunno what that works out to, but it’s a lot. Adding 1.5 teaspoon of calcium chloride and 1.5 teaspoon of bicarbonate in 1 liter causes a slow precipitation. Appears 1 teaspoon of each, calcium and bicarbonate per liter does not precipitate. Mixed 50% of this solution with tank water, still nothing falling out.

The pH is likely dropping from the bicarbonate addition, helping slow the precipitation.

 

[Garf]

I’ve been playing with my new found wonder solution, vinegar, lol.

Through dilution of samples, at 40 mls of vinegar per 2 liters of Kalk (heaped tablespoon of calcium hydroxide), I’m getting calcium at over 1500ppm and Alk greater than 200 DKH. So that’s approaching double standard Kalk numbers. PH appears to be around 12 (but my meter is only calibrated to 7 and 9.2). I’m guessing the amount dosed of this would be regulated by the amount of carbon entering the tank / evap.

I’ve also taken the opportunity to dose just while lights are on to stabilize Alk during the day and let my bubbly CO2 scrubber pick up the pH slack at night.

At work we treat effluent freshwater to maintain a pH of around 9 to force precipitation of controlled stuff, like phosphates to drain, I’m assuming I’m not dissolving anything in the Kalk that could be harmful, with the pH remaining so high.

Off to work soon, lovely.

 

[Randy Holmes-Farley]

If you haven't seen it, this old article by Craig Bingman may be interesting:

Aquarium Frontiers Biochemistry of Aquaria

 

[Garf]

Back to salinity today. I’ve been playing with a brine to slowly increase the salinity in a quarantine tank today. Tropic Marin Classic can be mixed up to 105ppt, and remain stable, it appears. This could potentially further increase the addition of Kalkwasser added to the tank, in conjunction with daily waterchanges.

 

[FishTruck]

FYI - for my system, volume is removed. A normal reefer would do this with a peristaltic pump just removing and discarding tank water a certain amount each day.

To replace it… in three components (kalk, ro/di, brine), I can get in a volume of kalk equal roughly to evaporate plus discarded water (5 gallons per day for example plus whatever the evaporation volume is) without overfilling.

Kalk goes in at a constant rate that I set. Brine goes in controlled by apex and conductivity probe. Standard ATO replaces whatever volume is still needed. The brine doesn’t need to be consistent- just briny. Fully dissolved would be best. As stated earlier- I cheat and cut corners and just dump salt in my brine bucket leaving up to a few inches of undissolved salt in the bottom of my bucket.