Instant ocean - white precipitate not dissolving

[ahmedess]

I bought some IO salt and it didnt dissolve completely. I had cloudy water and white precipitate after 2 days of running a powerhead in the solution.

I have tested the water for calcium, i got 400ppm and tested for alk, got 5 dkh. I dont have a magnesium test kit so i wont be able to test it. Calcium results seems fine but alkalinity is very low.

Knowing that i wont be able to return the salt i adjusted the alkalinity to 10dkh using baking soda and i used a spong filter to mechanically filter the precipitate and clear up the water.

Since Calcium is not low then I am assuming the precipitate is not CaCO3. Could any one tell me what this precipitate is?

[TheH]

Did you add water to the salt, or salt to the water? If the former, that has been known to produce cloudy water that won't clear up.

[nuccadoc]

I'm surprised you can't return the salt. I would not use a salt that does not completely dissolve.

[HighlandReefer]

If you take some of this precipitate and put it in some vinegar, my guess is it will fizzle. If so, it is most likely calcium carbonate.

If you add your salt mix too quickly to your water, this can result in precipitation, since the pH can rise too much. I would add your salt mix slowly into a full holding tank with the total volume of water you want mixed and mix the water well after each smaller amount you add.

[yeldarbj]

I think you posted this advice in a different thread. I used this technique on my last batch of water (with Seachem Reef salt). Not that I had much of a problem before, but I could tell it made a difference. Nice clear mixed water, no residue on the container, no precipitate.

[ahmedess]

I added the salt very slowly to the water. When i opened up the salt bag it was like a rock. I had to break it up into powder.

I will add vinegar to the precipitate to see what happens.

[VacavilleFC3S]

the salt is bad if it had already hardened in the bag, thats why the calcium precipitated

[ahmedess]

Could the precipitate be Mg, since i tested for Ca and i got 400ppm which is the correct amount of Ca in IO's salt?

[WI reefer55]

the salt is bad if it had already hardened in the bag, thats why the calcium precipitated

Can anyone else back up this statement?

[bertoni]

Calcium chloride and sodium bicarbonate, for example, can convert to calcium carbonate, and some byproducts, especially if the salt gets a lot of moisture in it, which is much the same as mixing the alkalinity and calcium solutions of a two-part together. The salt might harden some, and still be usable, though.

Magnesium carbonate is a bit hard to form, so I doubt that's the precipitate:

http://www.reefkeeping.com/issues/2005-07/rhf/index.php#18

I suspect it's just calcium carbonate.

[TheH]

Yes, as bertoni mentioned, if the salt was hard in the bucket that is likely from absorbing moisture and precipitating calcium carbonate. Since this calcium carbonate would not contribute to measured salinity when mixed with water, it makes sense that your calcium level is still reasonable, as you just had to add more salt to accommodate and reach the target sg.

[bertoni]

Adding more salt wouldn't help a low calcium problem very effectively. Any salt product contains a lot more sodium, chloride, and sulfate than calcium.

[Randy Holmes-Farley]

Since Calcium is not low then I am assuming the precipitate is not CaCO3. Could any one tell me what this precipitate is?



No, you probably cannot conclude that. Dropping alkalinity from 11 to 5 dKH (6 dKH) will only cause a 40 ppm drop in calcium even if it is all CaCO3 (but part may well be MgCO3). I'm not sure you have the ability to detect that with home kits unless you know how high the calcium was before the precipitation and was tested in the same way with the same kit.

IMO, it very likely is calcium or magnesium carbonate. In any case, I'd let it settle out and use the salt.

This has a lot more info, including discussion of the solids on the bottom of IO:

What is that Precipitate in My Reef Aquarium?
http://reefkeeping.com/issues/2005-07/rhf/index.htm

[ahmedess]

does the test kit also measure the solid particles suspended in the solution? I m asking this because if the test kit has an acidic reagent in it then it will dissolve the white precipitate and thus it will be accounted for in the test kit results.

[Randy Holmes-Farley]

An alkalinity kit will, yes. A calcium kit probably does as well.

[Randy Holmes-Farley]

I will also add that solids (like a salt mix) can get rock hard with no precipitation of calcium carbonate. All it takes is a little dissolution around each grain, and then that rehardening if it dries out a bit, cementing adjacent grains together. My bags of calcium chloride and magnesium chloride become rock hard over time, and there is no carbonate in them to precipitate.

That said, the same moisture that allows solids to dissolve and reprecipitate is also potentially going to allow some calcium and magnesium carbonate precipitation within the "wet" zones.

[ahmedess]

Forgot to mention that I have also tested my PH and found it to be 9.0 the first day. The second day the PH was 8.8. After I added baking soda PH droped to 8.6.

Should i adjust the PH using soda water before adjusting the alkalinity, Then after I adjust the PH I test for alkalinity and adjust it accordingly?

[Randy Holmes-Farley]

Sounds like a pH measurement error to me, or a mismade batch. How did you measure it?

[ahmedess]

Hanna digital PH meter. Its calibrated fine i double checked it when i got the wierd results. I have a chemical PH test kit i can check using it and see what i get but i m sure it wont differ. I tend to agree more with the mismade batch idea because the salt was sealed in an air tight plastic bag inside a box so theres no way humidity could have entered the plastic bag and caused the salt to go bad. I think it was mismade as you said

[Randy Holmes-Farley]

Do you have any undissolved salt mix from the bag still?

[ahmedess]

Yes

[Randy Holmes-Farley]

What portion of the bag did you make up? Maybe it had settled and became inhomogeneous.

[ahmedess]

What portion of the bag did you make up? Maybe it had settled and became inhomogeneous.

I dont think so because i mixed it all together. The salt was a single piece of rock and i crushed it all together to make it powder again but after that still it wasnt completely powder and it looked like snow

[Mounda]

It is a common issue with salt in our country. I too have used the salt in boxes and had the same issue with precipitate formation on the bottom of my mixing container; 30 gallon brute. Salt that is packaged in an air tight plastic bag and sold in IO or RC cardboard boxes usually has this problem over here. I have tried several batches (different batch numbers printed on the plastic bags) and they all seem to have the same problem.

Perhaps we could contact the company with batch numbers.

After using the boxes with disappointing results I opted for a bucket, the salt dissolved within seconds and no precipitate was formed. Buckets seem to be the way to go.

[Randy Holmes-Farley]

In that case, I expect the pH measurement was somehow incorrect. Salt mixes may start high in pH, but after mixing and aeration the pH should not be high, and if the alk is low (due to precipitation or any other reason), it definitely should not be high in pH after aeration.

[ahmedess]

i ll recheck using my chemical ph test kit

[ahmedess]

Randy,

i got a pH of 8.5 using the chemical test kit, same as the pH meter. so i guess there are no mistakes in pH measurments and its truely high. I m confused, but 8.5 is not really high if i use a bit more baking soda to increase the alkalinity a bit, my guess would be that the pH will go down to 8.3 which is okay and then i could also dose CaCl for the lost calcium, what do you think? its a lot to be done to a salt mix i know but as long as the salt will be good to use at the end then i have no problem of doing it. I really appreciate your help

[bertoni]

That's very strange to have a pH measurement that high. I'm not sure I'd worry about it. Adding baking soda and calcium chloride should help bring alkalinity and calcium back in line, although there might have been some loss of other minerals to precipitation.

[ahmedess]

i guess i ll have to make sure i buy better stuff next time.

[Randy Holmes-Farley]

Adding a bit of baking soda is an OK plan. How high are you going to boost alkalinity?

[ahmedess]

Adding a bit of baking soda is an OK plan. How high are you going to boost alkalinity?

I ll boost alkalinity to 11-12dkh, what do you think?

[Randy Holmes-Farley]

That is probably OK, but if you do not keep your tank that high, I wouldn't push the salt mix that high. I'm a little worried that you may see more preciptiation, even though normally it is OK.

[ahmedess]

This salt will be used to fill up a new tank. Do you mean if i increase alkalinity more precipitation will occur?

[bertoni]

Raising alkalinity that high might cause some precipitation. It's not clear why you're having problems; at least, I don't quite understand it, so I'm not sure what would happen.

[ahmedess]

Something that i might have misunderstood, I thought as alkalinity increases the saturation amount of calcium increases which i thought ment that more calcium can dissolve in water without precipitation.

I raised alkalinity to 11 dkh and there were no precipitation. Also i took a sample out of the water and raised its alkalinity to 15 dkh just to see what will happen and no precipitation occured also. Does that mean magnesium levels are fine or what?

[Randy Holmes-Farley]

Raising alkalinity that high might cause some precipitation. It's not clear why you're having problems; at least, I don't quite understand it, so I'm not sure what would happen.


Yes, that was my thought exactly.

Something that i might have misunderstood, I thought as alkalinity increases the saturation amount of calcium increases which i thought ment that more calcium can dissolve in water without precipitation.


Yes, you misunderstood. It is the opposite. Higher alkalinity and higher pH and lower magnesium means less calcium can be present before precipitation.

No I would not make any conclusion about magnesium levels from lack of precipitation. Many other things can stop it (organics, low pH, phosphate, low calcium, etc).

[ahmedess]

When i use this calculator http://home.comcast.net/~jdieck1/chemcalc.html it says that balanced calcium level increases as alkalinity increases what does that mean?

[bertoni]

The "balance" part of the calculator is meaningless. Please ignore it. It refers back to the author's choice as to the target saltwater levels.