Jan,

Rod really doesn't know what he is talking about when
he refers to Morton, because Morton has not used YPS
since the late 1940's. I asked Morton, so I know.

Tom L.L.
----------------------------------------------------
~ jan JJsPond.us wrote:

On Mon, 02 Aug 2004 10:42:58 GMT, "ciel" wrote:


I have a dilemma
I want to use some salt in my pond BUT.......
All my local suppliers ie: Aquatics Centres have a product PDV (pure Dried
Vacuum) Salt
This has Anti Caking agent E535 (Sodium ferrocyanide)


Our resident chemist who use to post he Rod Farlee wrote:

YPS (yellow prussiate of soda, sodium ferrocyanide) is a common
anti-caking additive in granulated table salt. Morton's has it, so "when
it rains, it still pours". It is potentially toxic to fish.

Table salt may contain up to 13 ppm YPS, and does not have to be
listed on the label, per FDA regulation (21 CFR 172.490).

When exposed to sunlight, ultraviolet light rapidly photolyzes YPS to
free cyanide. US EPA lists cyanide as toxic to fish at 0.022 ppm
(acute toxicity) to 0.005 ppm (chronic toxicity, "96 hr LC50" means it
kills half the fish in 3 days). Fortunately, cyanide isn't persistent; it
evaporates readily and bacteria can destroy it.

At the oft-recommended 0.1% salinity, salt with 13 ppm YPS would
put 0.013 ppm YPS in the pond, which could photolyze to 0.0044 ppm
HCN, which is near the toxic level.

If higher salinities were needed for disease treatment, cyanide could
exceed toxic levels.

If, on the other hand, lower salinities were used (e.g. 100 ppm for
prevention of nitrite toxicity), the low cyanide level would not be of
concern.

I use solar salt crystals, coarse 1/4 to 1/2 inch in size. It doesn't seem
to contain YPS (humidity causes it to fuse into a lump, which I break up
with a hammer or boot). An 80 pound bag was $6 on sale at Lowe's.
- Rod

Personally, I get Morton's water softener salt in the blue bag without
conditioners, 99.9% pure I think it says on it, no anti-caking chemicals
and only ~$4/40 lbs. ~ jan


(Do you know where your water quality is?)