how do you avoid precipitation of new salt water?

[sensei]

I am doing automatic WC so I am 30g of salt water and leaving it in a container. I use a power head to mix the salt with the water and in 15 min water is super clear, so I turn of the pump and leave it in the container, but next day water is always cloudy, showing some precipitation.
how can I avoid this??

thanks

[nicholasb]

If you have precipitation, then you would expect the calcium carbonate formed, to sink to the bottom, and not make the water go cloudy. You could try giving the bag of salt a good shake, to ensure the salt is properly mixed up. Maybe you have a bad batch of salt.

[sensei]

some goes to the bottom but some stays suspended as they are very fine particles.
I do not know if I should mix it more time at the begining or what else to do. Once water is cloudy even If I put a power head again, particicles do not dissolve.

I believe that temperature drops a couple of degrees over night and that may cause the precipitate.

any ideas?

[luisagos]

Originally Posted by sensei

I turn of the pump and leave it in the container, but next day water is always cloudy, showing some precipitation.
how can I avoid this??

thanks

What Brand are you using?
You will be surprise the instruction clearly states leaving the salt overnight is not advise in some salt brands.

[tmz]

Only one salt I can think of of the top of my head requires quick use after mixing; there may some others. Salts with high calcium and alk content are more likely to precipitate .

A temperature drop would increase the solubility; not decrease it;i.e. the cooler water can hold more alk and calcium in solution .

FWIW, I've keep a supply of mixed salt water
( 9dk , 480ppm. calcium)continuously, in a 20 gallon bin ,replacing it as I use it and have for a decade without any precipitation

[sensei]

I am using red sea salt preparing it to 1.026 SG.

[bertoni]

Have you measure the alkalinity before and after the precipitation forms? If there's not much drop in the alkalinity, I suspect that the water is okay to use. You'll need to let a sample settle to get a reasonable reading, since the alkalinity test might redissolve the precipitate.

[luisagos]

Originally Posted by sensei

I am using red sea salt preparing it to 1.026 SG.

Is it the pro or the normal one ?
Do you trust your method of testing salinity, and what are you using to test it with ?

[sensei]

Originally Posted by bertoni

Have you measure the alkalinity before and after the precipitation forms? If there's not much drop in the alkalinity, I suspect that the water is okay to use. You'll need to let a sample settle to get a reasonable reading, since the alkalinity test might redissolve the precipitate.

yes, after mixing with no precipitate I got 10.5, 2 days later 7.2
but even after the 2 days water looks cloudy, some settles in the bottom of coarse.

I used 25 g in my 150g dt and the skimmer was able to skim the suspended precipitate quickly.

last week I prepared another batch of same salt but that one did not precipitate over night. I am not sure if I left if mixing more time when I added the salt but I have tried preparing 2 more batch after that and I always get the precipitate over night. any ideas?

[sensei]

Originally Posted by luisagos

Is it the pro or the normal one ?
Do you trust your method of testing salinity, and what are you using to test it with ?

I used the normal one, NOT the pro.
alk is higher that what they claim becuase I use more salt to have 1.026 SG

I use a calibrated 1.026 solution to calibrate refractometer before measuring. calibrated refractometer makes the test accurate.

[MakomekTVN]

I have used the red sea(blue bucket) and when mix at 1.026sg alk around 7-8 dkh . 10.5 dkh is either your refractometer or alk tester is off. I recently switch to different brand due to my tank running low ph (7.7-7.9) and red sea salt mix ph at a crazy high ph 8.7 cause my tank to spike more than .3 during WC and if I wait for 24 hour the PH drop back down but the water is cloudy. I switch to Fritz salt and I can do a WC within 2 hours or leave it till next week without issue.

[bertoni]

I'm not sure why you are seeing the precipitation. I wonder whether the initial high pH is the problem, leading to further precipitation later. Once small crystals of calcium carbonate form, they might encourage further precipitation. Magnesium helps control this problem, but some precipitation should be expected if there are a lot of surfaces available for precipitation.

[sensei]

Thanks,
It takes about 4 days for the water to be cristal clear and have the precipitation in the bottom of container.

is it recommended to have a power head moving the new salt water until you use it?

or it does not matter if you have it in a container with out any movement?

[bertoni]

The power head won't help with precipitation, if that's the problem, but it might help if the saltwater is getting an odor from decay. I never bothered with a pump in my stored saltwater, but I was using IO most of the time, which has no organics.

[sensei]

thanks a lot

[bertoni]

You're welcome. Good luck!

[sensei]

bertoni,
one more question,
before I used to prepare a big batch of salt water that lasted 3 week consumption in all my tanks, but now I am preparing small batches for only 3 days so that alk does not drop that much in the newly prepared salt water.

the funny thing is that after doing the water change with this freshly prepared salt water ORP increased 10% in the APEX. any idea why?
here is the picture of the apex

ORP.jpg

thanks again

[bertoni]

ORP is a funny thing to measure. There might be some residual organics in the mix, or the water change might be spurring some sort of biological activity. I don't know of any reasonable way to discover what's happening.

[tmz]

FYI:
Table 2. Some oxidizers and reducers in marine aquaria.
Oxidizers:

O2 (singlet oxygen), 3O2 (triplet oxygen), O3 (ozone), H2O2 (hydrogen peroxide), OH (hydroxide radical)

Metals: Fe+++ (iron), Mn++++ (manganese), many others

Some organics (e.g., organic peroxides, radicals)

Inorganics: SO4--(sulfate), NO3- (nitrate), NO2- (nitrite), IO3- (iodate); Cl2 (chlorine), ClO- (hypochlorite), BrO- (hypobromite)

Reducers:

Metals: Fe++ (iron), Mn++ (manganese), many others

Most organics, especially "antioxidants" like vitamin C

Inorganics: I- (iodide), S-- (sulfide), NO2- (nitrite), NH3 (ammonia)

from this article:

http://reefkeeping.com/issues/2003-1...ture/index.htm

An increase in oxidizers or decrease in reducers raises ORP.

[ktownhero]

For stored salt water, I use regular IO -- never have these problems.

For doing smaller water changes, I keep a box of "reef salt" around. I've used RSCP and now have some Reef Crystals arriving. I can't speak for the regular Red Sea stuff, but RSCP very clearly states that you should use it within 4 hours of mixing else you get precipitation. And, unfortunately, that's true. Great salt otherwise, but I find that annoying.

[sensei]

Thanks for your answers.

I need to store salt water for to do automatic water changes in my 600g system.
I am doing 1.5% daily WC.

I do not know of having a powerhead in the prepared salt water container will help to reduce the precipitation or at least avoid it to some degree??

I ask because salt water is saturated so precipitation will tends to occur and that precipitate encourages more precipitation.

any comments?

[bertoni]

The powerhead might encourage a bit more precipitation, at least in theory, although I suspect it doesn't much matter as long as the salt product has no organics in it. Products with organics might do better with a powerhead to keep the decay process from producing an anoxic environment, which could lead to toxic metabolites from the anaerobic decay.

[sensei]

Thanks Bertoni,
there are no organics, since it is new salt water.
I will add some Magnessium to the new water to see if that helps in the new batch I will prepare tomorrow.

thanks again

[tmz]

What brand of salt is it?

FWI. I keep salt water stored continuously in a bin with a very small power head running and have for many years without precipitation. Most slat mixes I know won't precipitate anything at normal seawater salinitiy levels.

[sensei]

Red sea salt, blue bucket.
the water get cloudy over night, after 3 days water is clear again and the precipitate is on the bottom.