Calcium sulfate, very insoluble!

[7Enigma]

Just a quick heads up. I purchased a recent assortment of replacement nutrients from Greg and thought that it would be a great idea to use calcium sulfate instead of calcium chloride (especially because my QT tank is a snail farm right now and everyone knows salt and snails don't mix ).

Well I never thought to check the solubility of the compound (as most sulfate compounds are readily soluble) but needless to say I now have 1/4 teaspoon of what appears to be snow on my substrate. That was only after I beat it all off the leaves which were covered with the stuff.

It's now been about an hour and I don't see any less than when I originally dumped it in. This really ticks me off because I bought 2 lbs of it thinking this would be my main calcium source, along with calcium chloride (fortunately I purchased a pound as a just in case measure), and also some calcium carbonate (which I KNOW has very low solubility). The latter was for my snail tank so that it would slowly dissolve in the water and make sure their shells always had enough calcium.

HTH!

Oh and just to mention, I've purchased from Greg now twice and have nothing but great things to say! (just wish he would put a disclaimer on the solubility, I sent him an email requesting that)

EDIT:

Just googled and came up with this nice chart showing solubilities of several of the chemicals we use. It's at the bottom of the page.

http://wwwchem.csustan.edu/chem1112/1112UnknownNEWed1.htm

 

[Peyton]

I use calcium sulfate all the time. It does take a few hours to dissolve all the way but I usually dose early in the morning several hours before the lights come on. It's always disolved by the time they do come on. I only dose 1/8 tsp though.

 

[IceH2O]

wow I never had a problem with CaSO4 dissolving in my tank. I know it took a bit longer then the others but not long enough to notice it even 30 minutes later.

I've been thinking of switching over to CaCO3 but more because my KH is non existent. My tank with snails I have to add baking soda to keep the pH and KH up. I just don't know how much CaCO3 it will take to keep it at the same level.I don't want to jump it to quickly. At least I was able to find how much baking soda it took.

 

[Burks]

Calcium Carbonate does the same thing for me.

I just add whatever amount I need to into the AC 20 filter and let it dissolve in there. Works well.

 

[Plantbrain]

I add it into the filter or somewhere there is high water flow out of sight.
It dissolves but many Ca salts are slow, CaCl2 is the only fast one really that does not mess with KH/pH.

CaO, Ca(OH)2 are some others, quick lime and lime.
The GH booster Greg sells and SeaChem Equilibrium also use CaSO4.


Regards,
Tom Barr

 

[hashbaz]

I bought some of Greg's CaSO4 and used it for the first time this week. I actually thought the "snowy look" was kind of cool. The "snow" was all gone by morning. The clumps were gone in 48hrs.

CaSO4 will dissolve - it just takes a long time. Is there any way to speed up how fast it dissolves? I added roughly 1/4 cup to 3L of hot water and shook the snot out of it and had little effect. In calcium reactors don't they use carbonic acid (from CO2) to dissolve calcium carbonate?

 

[Zezmo]

Working it with a mortar and pestle first will help it dissolve a bit fast too.

 

[7Enigma]

So I was in a hurry this morning and didn't check to see if it was gone, but hopefully based on the stories here it is. Hopefully my CO2 system will speed up the dissolving.

Working it with a mortar and pestle first will help it dissolve a bit fast too.

Nope Greg's stuff is very fine, looks and feels like talc powder. His calcium chloride looks like pieces of real parmasean cheeze (ie large flakes).

I bought some of Greg's CaSO4 and used it for the first time this week. I actually thought the "snowy look" was kind of cool.

While that snowy look might be cool I'm concerned if it gets into the impeller. Just like fine sand, this stuff would/could over time damage the impeller.

I'm sure you could speed it up with addition of an acid, but I'd prefer not to do that for obvious reason.

IceH2O,

Calcium carbonate is essentially crushed coral/shells. It has a MUCH lower solubility rate than even calcium sulfate (otherwise you would see shells just disappearing in the tank). You can check that site I linked in the first post for a comparison. Because of this I personally would not use it for exclusive double duty (both calcium AND for KH). Maybe have it as part of the buffering, using baking soda for the rest (since that dissolves relatively instantly).

Thanks to everyone for the replies. I'll just have to find a better place to dump it so it doesn't bother me or damage equipment. Let's hope the fish don't eat it in large amounts.....because they normally go after the other ferts if a clump sinks by them.

 

[maxwell1295]

Try nuking a cup of water in the microwave for about 35-45 secs and then stir it in. That might help speed up the process. That's how I get the calcium chloride and epsom salt to dissolve faster. I hate adding undissolved clumps of anything to the tank. The fish seem to think it's food and try to eat it.

 

[malkore]

This is a frequent occurance in SW tanks. I'd suggest you edit the subject, as I don't want Greg Watson to get a bad reputation when its not his fault. Calcium precipitate is not to be blamed by his ferts.

 

[7Enigma]

This is a frequent occurance in SW tanks. I'd suggest you edit the subject, as I don't want Greg Watson to get a bad reputation when its not his fault. Calcium precipitate is not to be blamed by his ferts.

I think you misunderstood the OP. This is not calcium precipitate that is developing on the walls or decorations of the tank. Its the chemical insolubility of the fertilizer....

I clearly stated in my OP it had nothing to do with Greg and I only have praise of his service and prices. I would, however, have liked a disclaimer on the solubility.

I came home today and can't find any left in my main tank, but in my QT tank I still have some small clumps. So less than 24hours if its not clumped together isn't so bad. I'll probably continue to use it just more carefully. I'm still concerned about it getting picked up in the HOB.

maxwell1295,

I don't think that will do much. Both calcium chloride and Epsom salt (magnesium sulfate) dissolve very well in water (they are both on that chart in the link I provided in the OP). I think the calcium sulfate has to be chemically broken down, and I'm assuming my CO2 is probably partly responsible (would also make sense as the QT tank still has visible signs).

 

[Purrbox]

I have to agree with Malkore about the wording of the subject.

Don't buy calcium sulfate from Greg Watson!

This reads like the problem is with Greg Watson, even though at the end of your first post you clarify that you've never had a problem with Greg Watson, just this particular product. The problem is that someone might not read your post or the rest the thread, and as a result they would probably think the problem was with Greg Watson.

 

[7Enigma]

I have to agree with Malkore about the wording of the subject.

Don't buy calcium sulfate from Greg Watson!

This reads like the problem is with Greg Watson, even though at the end of your first post you clarify that you've never had a problem with Greg Watson, just this particular product. The problem is that someone might not read your post or the rest the thread, and as a result they would probably think the problem was with Greg Watson.

Fine, I changed it.

To be honest I was using that title for the impact as I suspected that just saying, "Don't use calcium sulfate" would not get the same response...