Un-dissolved powder from salt mix(caking salt)

[Gqch]

Hi everyone here! Mixing salt for water changes today, i see the salt kind of caking up a little but no to hard, after i mixed it with rodi water, realized some powder in the salt mix never dissolved. Question, what's those white powder and are they harmful to the corals? Thanks in advance guys!

 

[Jay Hemdal]

Hi everyone here! Mixing salt for water changes today, i see the salt kind of caking up a little but no to hard, after i mixed it with rodi water, realized some powder in the salt mix never dissolved. Question, what's those white powder and are they harmful to the corals? Thanks in advance guys!

Welcome to Reef2Reef!

What brand of salt are you using? Did you let the mix get really saline? (Like adding a lot of salt to a small amount of water).

Jay

 

[Gqch]

Welcome to Reef2Reef!

What brand of salt are you using? Did you let the mix get really saline? (Like adding a lot of salt to a small amount of water).

Jay

No, i add salt little by little into 45 gallons Rubbermaid. When salt was normal, salt water clear up in 5min.

 

[innovusaquaculture]

I put a 1 micron sediment filter inline on my mixing pump for my salt water mixing brute container. Every week I change it out. On amazon you can buy 50 of them for $60 and a clear housing for $28. That takes care of everything and leave my containers very clean. I use Instant Ocean Reef Crystals.

 

[Gqch]

I am using redsea pro salt, never happen b4 like this. It happens cuz the salt that have left has clot (caking) a little, even it's not to bad but still leave tons of white powders on the button of the container.

 

[Jay Hemdal]

No, i add salt little by little into 45 gallons Rubbermaid. When salt was normal, salt water clear up in 5min.

I've had a white precipitate form with Instant Ocean when mixing it up at above double salinity. My supposition is that this created an insoluble material (calcium carbonate?). True, this can be filtered out, but my thought is always that what ever it is I am removing was supposed to be in the salt mix and now I've removed it.

Jay

 

[Randy Holmes-Farley]

As noted, the precipitate is mostly calcium carbonate, and it generally forms from all high alk salt mixes, especially if they get heated. It is not any sort of tox concern.

Here's what my mixing barrel looked like after a few years:

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com

Solid Residues Remaining After Preparing Artificial Seawater
Most salt mixes leave behind a solid residue when dissolved, although the extent to which this occurs varies from brand to brand. I use Instant Ocean and rarely clean out the 44-gallon trashcan that I mix it in, so a significant residue builds up over time (Figure 1). In preparation for this article I removed some of this solid material, and found that it could be almost completely dissolved in hydrochloric acid with lots of bubbling. This demonstrates that these solids were probably calcium carbonate (CaCO3), perhaps also containing magnesium. Pure magnesium carbonate is undersaturated in seawater (which is detailed in later sections of this article) 1 and should dissolve in marine systems, so it isn't likely to be the precipitated material, although there may be significant magnesium in the calcium carbonate.
Based on the fact that the material exists as sheets that clearly did not arrive in the mix (as opposed to a fine powder which might have), I conclude that at least a significant fraction of this residue formed in the barrel. I cannot, however, rule out the possibility that some solid calcium or magnesium carbonate may have existed in the salt mix and was cemented together by additional precipitation of calcium carbonate during dissolution or storage.

When salt mixes are dissolved, there exist local regions where the salt concentration is very high. In those local regions, the calcium and alkalinity must also be very high. In fact, as seawater is concentrated by evaporation, there is a well-established series of minerals that precipitate as the salinity increases. In this series, calcium and magnesium carbonate are the first to precipitate, appearing at a specific gravity of about 1.140, which is about a 50% solution of salt in water.1 Such conditions may well exist on the bottom of a saltwater reservoir as the salt is dissolving.

With some mixes (but not the Instant Ocean that I use), the initial pH on dissolution may be very high (pH 8.5-9 +). As shown in detail later in this article, pH can play a dominant role in determining the rate of calcium carbonate precipitation, and such a high pH would make it more likely to precipitate.

It has been suggested by some aquarists that some salt mixes may contain anti-caking agents, such as clays. I do not know if this is true, but if it is, they may form part of the residue that is left behind after dissolution.

In order to minimize the formation of insoluble carbonate salts when mixing, the following suggestions may be helpful:

1. Add the salt to a full batch of water, rather than adding water slowly to a large batch of salt. The latter allows a greater time at much higher than natural seawater salinity, which may tend to precipitate calcium and magnesium salts.

2. Stir the mixture vigorously as it is being dissolved.

3. If using a mix with a high initial pH, aerate the mixture as well as stirring it. The aeration will reduce the pH.

 

[innovusaquaculture]

I've had a white precipitate form with Instant Ocean when mixing it up at above double salinity. My supposition is that this created an insoluble material (calcium carbonate?). True, this can be filtered out, but my thought is always that what ever it is I am removing was supposed to be in the salt mix and now I've removed it.

Jay

Jay,

I was of the same opinion, so I resisted adding the filter to my setup for a long time. I eventually came to the conclusion that I wasn't going to get what I was filtering out to go into solution over any length of time or with any amount of stirring. I just decided that I didn't want the ugly brownish sludge to go into my tank(s) at some point and I was tired of doing maintenance on the storage tanks.

I tried several approaches. Mixing first, then filtering. Just mixing. Mixing while filtering. I tested each batch for Ph, Ca, Mg, Alk and trace and all came out very close to the same. Apparently what I am filtering is insignificant to what I am testing or something that I can't test for.

Your thoughts. I respect your option as a master at this craft over anything I could accomplish?

 

[Randy Holmes-Farley]

FWIW, I think the brown "sludge" that folks often see with IO Reef Crystals is a different material than what folks see with normal IO or with other high alk mixes such as Red Sea Coral Pro.

In that case, I think it relates to the vitamins and maybe the chelators they add, and it may be bacteria or precipitating vitamins.

 

[Jay Hemdal]

FWIW, I think the brown "sludge" that folks often see with IO Reef Crystals is a different material than what folks see with normal IO or with other high alk mixes such as Red Sea Coral Pro.

In that case, I think it relates to the vitamins and maybe the chelators they add, and it may be bacteria or precipitating vitamins.

Randy, I always wondered if the brown crud in IO related to the lower purity of the mag chloride they were supposedly using. Could it be some sort of insoluble iron salt? Back in the day, when we mixed salt ourselves we were buying mag chloride prill from Germany that was supposed to be purer, I recall my curator saying something about wanting to avoid domestic product to avoid rust from the inside of the grinding mill….but that was 35 years ago, I may be misremembering that.

Jay

 

[Randy Holmes-Farley]

Randy, I always wondered if the brown crud in IO related to the lower purity of the mag chloride they were supposedly using. Could it be some sort of insoluble iron salt? Back in the day, when we mixed salt ourselves we were buying mag chloride prill from Germany that was supposed to be purer, I recall my curator saying something about wanting to avoid domestic product to avoid rust from the inside of the grinding mill….but that was 35 years ago, I may be misremembering that.

Jay

I suppose it could be almost anything brown, but it seems strongly associated with Reef Crystals and not normal IO, which I would guess uses similar chemicals (aside from the vitamins and metal chelator(s)), but I do not know that.

 

[Gqch]

The white un-dissolved powder was most likely the mag chloride! It happened to caking salt(salt with high moisture and get clot) only. I kind remember i have read it from somewhere before, then jay hamdal' reply just reminds me! Plz correct me if i am wrong. Thanks!

 

[jmichaelh7]

I just started using IO from the switch from TMP. i noticed the white matter in the brute can. I researched it and found this thread.

I guess its safe to say that it doesn't impact the aquarium , or reef? Or is this stuff pretty much going inside the aquarium and on the equipment too?