dumb question

[Ron Reefman]

OK, I've been using IO Reef Crystals for years. And every time I mix it up, some white sediment settles to the bottom. I've never worried about it, I'm just a bit careful about not getting it into my tank.

But I've used 10g of the 20g mix I had prepared. So I added 10g of RO/DI and mixed with a big pump. The white stuff still didn't dissolve? I use a Brute to mix in and I always keep it clean.

I'm not worried about it, but I am curious about what it is and do other Reef Crystal users get the same thing?

 

[newbie2014]

I only get the white residue if I use old clumpy leftover RC. And I have no idea what it is. So far I haven’t seen the fresh powdery RC leaves any white residue.

 

[HeyJay]

I've always had brown residue. Think it's just a fact of life when using RC.

 

[Softhammer]

I can attest to residue as well. Always assumed it was calcium precipitation. Never had issues other than it being a pain cleaning out my mixing tank each time. And it did turn brown if it sat For a bit.

 

[dank reefer]

I used RC for about 1 1/2 and never had the brown residue I hear everyone else talk about. I maybe saw once where there was a bit of white residue in the bottom of my brute can, but it was sorted out the following day once the water came up to temp.

 

[PicassoClown04]

I’ve always had quite a bit of white residue at the bottom of the mixing barrel, I keep it stirred 24/7 with a powerhead as well

 

[brandon429]

the brown residue for twenty years in my topoff containers are highly reactive to 35% peroxide, borderline explosive heh.

so tracing from that: higher organic inclusions in rc vs others + hydration + precipitate substrate + constant filth incoming contamination from septic handling and we have a microbiome at the bottom of our water change containers that runs independent from our tanks. burn it with chlorine, watch it melt away and pour out as sloughs

I miss dirty rc water. my lfs uses only cheapest fritz and its dissolving my skeletons Im having to change water much more often to keep the mass constant. yet i still cannot bring myself to prep for 1 gallon of water change

 

[chipmunkofdoom2]

It's not undissolved salt mix, it's calcium carbonate precipitating out of solution. Reef Crystals has very high alkalinity which leads to precipitation under conditions found in typical seawater. The reason it does not dissolve when you add more freshwater is because calcium carbonate will not separate and dissolve into seawater at normal pH ranges. This is the reason calcium reactors require CO2. At normal seawater pH ranges calcium carbonate coral skeletons will not dissolve. By adding CO2, the pH drops to the point where calcium carbonate can dissolve back into solution.

 

[vetteguy53081]

Agree on carbonate that will not dissolve. I generally pour that remainder into the sump

 

[brandon429]

rushes home to put 35% peroxide on a dry coral skeleton test

if i recall I think it will fizz up a little, can't recall. the dry septal part not a cruddy grown organic attachment section/dry part
does peroxide react to dry caco3?

update, it does not. Takes an organic inclusion apparently. Strong peroxide didn’t react with dry caco3.

 

[Ron Reefman]

I used RC for about 1 1/2 and never had the brown residue I hear everyone else talk about. I maybe saw once where there was a bit of white residue in the bottom of my brute can, but it was sorted out the following day once the water came up to temp.

I mix my water in a garage and the water temps get quite high and the residue does not go away for me.

It's not undissolved salt mix, it's calcium carbonate precipitating out of solution. Reef Crystals has very high alkalinity which leads to precipitation under conditions found in typical seawater. The reason it does not dissolve when you add more freshwater is because calcium carbonate will not separate and dissolve into seawater at normal pH ranges. This is the reason calcium reactors require CO2. At normal seawater pH ranges calcium carbonate coral skeletons will not dissolve. By adding CO2, the pH drops to the point where calcium carbonate can dissolve back into solution.

Thank you, thank you, thank you chipmunkofdoom2. Finally an answer that makes sense to me. I readily admit to being a physics guy and not at all a chemist. But I understand just enough to recognize that what you said makes perfect sense. Thank you!