Exceeding the limewater evaporation limit

[Garf]

Bit of a back story. In my old tank, many moons ago I used to do waterchanges by pumping in low salinity water, which used to overflow out of the acrylic sump, caring for the saltwater change and 75% of my evaporation, in one pump. The other 25% of the evaporation was taken into account by kalkwasser dosing.

Currently, I’m at the maximum evaporation limit on my tank, when dosing saturated kalk with 45mls vinegar/gallon. I change out 1.5% of my saltwater daily. Taking into account the above, can anybody think of a good reason why I can’t flip my previous process. For example, I would remove 3 litres of salt water daily and slowly pump in a strong saltwater solution, then this would leave extra room to increase the kalkwasser additions (I do not have an ATO or skimmer).

I’m assuming I can actually get enough salt in the strong mixture without precipitating anything and would be a trial and error game.

If anyone has tried this, please let me know how it went :)

If all else fails I’ll probably do All For Reef but I’m not adverse to 2 part. So many options.

 

[Heabel7]

That seems incredibly risky. I just turn on a small fan. It’s actually shocking how much you can increase evaporation with a little air movement.

 

[Randy Holmes-Farley Verified Community Expert]

If you try to boost salinity, I recommend a low alk mix to reduce risk of precipitating calcium carbonate (one of the first things to precipitate when evaporating seawater).

 

[Garf]

If you try to boost salinity, I recommend a low alk mix to reduce risk of precipitating calcium carbonate (one of the first things to precipitate when evaporating seawater).

Thanks, I’ve got hydrochloric 36% for emergencies, I could destroy the Alk and see how high my salt can go before any visible precipitation. In real life however my increase in Alk consumption will be slow and therefore the increase in salinity I will need to offset the extra limewater. I think I may need another saltwater mixing bin, so the wife don’t use it by mistake in her tank though, if I get to that stage.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks, I’ve got hydrochloric 36% for emergencies, I could destroy the Alk and see how high my salt can go before any visible precipitation. In real life however my increase in Alk consumption will be slow and therefore the increase in salinity I will need to offset the extra limewater. I think I may need another saltwater mixing bin, so the wife don’t use it by mistake in her tank though, if I get to that stage.

In low alk and pH, you can probably go pretty high. 2x salinity might be attainable.

 

[Garf]

In low alk and pH, you can probably go pretty high. 2x salinity might be attainable.

Playtime;

Using Tropic Marin Classic I slowly added salt to RODI, with just a standard spoon stir. At 80 grammes/litre the solution appeared to become slower to dissolve. After a few minutes however, crystal clear, measured Alk at approx 19 DKH.
I’ll leave the solution covered for a day or 2 then retest Alk, it’s also in a glass to see if anything settles out, unstirred. This is achieved without Hydrochloric, water temp at about 10C. In effect this would double my kalkwasser dosing limit, replacing 1.5% daily.
I’ve put 250 mls in my dripper container and dosed it to the tank expecting to detect a brine haze enter the water but no, nothing.

LOL;

 

[Randy Holmes-Farley Verified Community Expert]

Playtime;

Using Tropic Marin Classic I slowly added salt to RODI, with just a standard spoon stir. At 80 grammes/litre the solution appeared to become slower to dissolve. After a few minutes however, crystal clear, measured Alk at approx 19 DKH.
I’ll leave the solution covered for a day or 2 then retest Alk, it’s also in a glass to see if anything settles out, unstirred. This is achieved without Hydrochloric, water temp at about 10C. In effect this would double my kalkwasser dosing limit, replacing 1.5% daily.
I’ve put 250 mls in my dripper container and dosed it to the tank expecting to detect a brine haze enter the water but no, nothing.

Looking forward to the results. :)

 

[Garf]

Looks like I’m good to go. Alk today tested at over 19DKH, nothing visibly settling.

 

[FishTruck]

I have been doing something similar to this for three years. Looking forward to what you report.

 

[Garf]

I have been doing something similar to this for three years. Looking forward to what you report.

Just had a gander at your build thread, wow. So your using brine to replace lost salts when processing tank water through a dialysis machine, never seen that before. Just one question “How Briny is your brine?.

 

[FishTruck]

Just had a gander at your build thread, wow. So your using brine to replace lost salts when processing tank water through a dialysis machine, never seen that before. Just one question “How Briny is your brine?.

Thanks... just checked out your tank... I love nearly cubic tanks and you are doing great with those acros!

How briny? That depends... and... that part is relevant to what you are doing. This is work done by Ken Feldman

https://reefkeeping.com/issues/2006-04/pr/index.php.

With a layer of undissolved salt in the bottom of your container... this shows that the brine supernatant changed week by week, despite the presence of solid salt at the bottom of the bucket. In my case... if my brine is having trouble maintaining salinity - I need to add fresh salt and agitate the solid stuff at the bottom.

When I started this... I assumed incorrectly that the brine would stay stable, so long as there was solid salt at the bottom, but, this is not what happens according to this experiment and IME as well. In this case, tank water is being slowly dripped through the brine bucket and back into the tank.

 

[Randy Holmes-Farley Verified Community Expert]

Looks like I’m good to go. Alk today tested at over 19DKH, nothing visibly settling.

Good to hear, thx for the update. :)

 

[Randy Holmes-Farley Verified Community Expert]

Thanks... just checked out your tank... I love nearly cubic tanks and you are doing great with those acros!

How briny? That depends... and... that part is relevant to what you are doing. This is work done by Ken Feldman

https://reefkeeping.com/issues/2006-04/pr/index.php.

With a layer of undissolved salt in the bottom of your container... this shows that the brine supernatant changed week by week, despite the presence of solid salt at the bottom of the bucket. In my case... if my brine is having trouble maintaining salinity - I need to add fresh salt and agitate the solid stuff at the bottom.

When I started this... I assumed incorrectly that the brine would stay stable, so long as there was solid salt at the bottom, but, this is not what happens according to this experiment and IME as well. In this case, tank water is being slowly dripped through the brine bucket and back into the tank.

That will certainly happen. I would NOT EVER recommend using a brine over undissolved salt mix. Different materials are known to precipitate at different salinity as you concentrate seawater more and more, and thus the brine never reflects a seawater ratio of ions if there is any solid present.

 

[Garf]

Ive now wandered into the realms of decreasing salinity with kalkwasser, operation “Weak brine” underway.

 

[TokenReefer]

Ive now wandered into the realms of decreasing salinity with kalkwasser, operation “Weak brine” underway.

How much does it take for salinity to decrease? What volume of water?

 

[Garf]

How much does it take for salinity to decrease? What volume of water?

It takes a while at the moment. I’m adding an extra couple of litres of kalk more than is evaporating in a 200litre tank, so theoretically dropping salinity 1%/week hence the weak brine to stabilise. However, this is just the start. Current alkalinity consumption around 1.7 DKH, with the possibility to run all the way up to 4 DKH or thereabouts, using vinegar in kalk, and strong brine, if my sums are correct. Cheers

 

[TokenReefer]

It takes a while at the moment. I’m adding an extra couple of litres of kalk more than is evaporating in a 200litre tank, so theoretically dropping salinity 1%/week hence the weak brine to stabilise. However, this is just the start. Current alkalinity consumption around 1.7 DKH, with the possibility to run all the way up to 4 DKH or thereabouts, using vinegar in kalk, and strong brine, if my sums are correct. Cheers

Interesting. Thanks for the info

 

[Garf]

Don’t really understand how this is possible but I’ve mixed up a saltwater solution of 90DKH, modified with bicarbonate. No visible precipitation, calcium still at 380. I was expecting a snowstorm to be honest. New saltwater at 400ppm calcium, 9 DKH.

 

[Randy Holmes-Farley Verified Community Expert]

Don’t really understand how this is possible but I’ve mixed up a saltwater solution of 90DKH, modified with bicarbonate. No visible precipitation, calcium still at 380. I was expecting a snowstorm to be honest. New saltwater at 400ppm calcium, 9 DKH.

Do you know the pH?

New salt water or used tank water (harder to precipitate)?

It it stays stable long enough, it might be interesting to drop some solid calcium carbonate into it and see what happens as they can seed precipitation.

 

[Garf]

Do you know the pH?

New salt water or used tank water (harder to precipitate)?

It it stays stable long enough, it might be interesting to drop some solid calcium carbonate into it and see what happens as they can seed precipitation.

New saltwater. I'll try that when I get home :)