Storing saltwater concentrate/slurry?

[johntan]

Wondering if anyone does this, I'm automating my water changes but delivering dry salt is problematic.
Is it better to use a brine (I've heard 4x salinity is the limit) or is a slurry ok?

I'm looking to have it stored in two week intervals, my concern is that cal or other elements will precipitate out. Thoughts?

 

[Coalminer]

Not a specific answer, but I would be concerned about the storage temperature and trying to calculate how much to use in mixing. I know that the temperature of the solution can dramatically change the solubility of the salt. So maybe the limit is 4x at 78 degrees, but at 65 degrees...?

 

[johntan]

Hmm, I'm mixing by weight if that makes sense. So at the initial mix the water would yes be too cold, but since the concentration is correct once brought up to temp the density would then be corrected.

If I have my slurry bucket filled with 4 gallons of RODI, and then 2.4kg salt (roughly 4x concentration so that's a brine) each gallon of this reconstituted with 3 gallons of additional RODI would make 4 gallons of 1.026 once brought up to temp. The program I have depends on four float switches being in the 'up' position (two at three gallons for rodi-primed and two at 4 gallons for brine-added in a 5g bucket for safety). Once all four are in agreement of mix prepped heat + a mix pump are activated.

If I can't get that to produce a fairly accurate mix I'm going to have to get a salinity circuit and probe. Then yes heat the water before adding the concentrate/slurry for an accurate reading.

My big concern though is that my slurry will precipitate, and I'd rather not try to use a powder, I'm worried it would get humid possibly clumpy and powdered salt + electronics don't mix.

 

[cilyjr]

So you are doing this to automate WC. Why the need for the concentrate?
I mean why are you not mixing an amount of saltwater normally then using a dosing pump to change water? I'm not understanding.

I do 2 gallon daily changes automatically. I mix 30 gallons then it changes out in 2 weeks time. With little calcium parciptation and no visible evap issues with a tight lid on the storage bucket.

 

[dannyp02908]

Maybe reefkeeper2 will chime in. I believe he has done this.

 

[cilyjr]

I believe Paul changes water similar to how I do. Though the old dyalisis machine might have required something like this

 

[johntan]

With a concentrate I can pull from one rodi resivior for ato and wc, and keep much smaller storage tanks. Just one large 'waste' tank if that makes sense. The concentrate or brine would also be changed very infrequently, yeah I believe the dialyseas machine used a slurry.

 

[cilyjr]

So the idea is to save space. That makes sense

 

[Greg Hiller]

With existing salt mixes I would not attempt to do this. Calcium and carbonate will find each other and start to precipipate out, particularly when they might not be completely dissolved to begin with. This is why the composition of water in places like the dead sea is not simply concentrated in everything. Some chemicals 'find' each other and start to selectively precipitate.

 

[johntan]

Shoot, that's what I was afraid of. Alright thanks anyway!