liquid dechlorinator and other questions

[Russ Little Pond]

How long does liquid dechlorinator stay active after the pond is refilled ?
does liquid dechlorinator effect water samples when testing ?
What is the shelf life the chemicals in test kits before it degrades ?
Does KH have a saturation point in a pond system ?

Russ.

[Duncan]

hi Russ

of course how long dechlor stay active depends on how much you use as there is a very high LC50 for it

ive had it stick around for up to 7 days after being deployed

no chlorine does not effect either type of test kit, thats both nestler and silicate unless you are using a dechlor with an ammonia lock in it in which case they could and probably would read garbage

best dispose of them after 12 months though i have tested them and found them good up to 24 months

last question, i dont really know mate, its not something thats ever come up before, might be time for an experiment but i would suspect that long before we got to a saturation or high concentration point it would be detrimental to koi/fish health

dunc

[Manky Sanke]

Does KH have a saturation point in a pond system ?

That's an interesting question (for those of us who need to get out more). Strictly, everything has a saturation point in water and there are different factors that have to be taken into account such as temperature and what else is also dissolved. Some chemicals dissolve to a far greater extent if another chemical is present than they do if it isn't.

An example is using oyster shells as a source of calcium carbonate (CaCO3) to buffer pH.

At 20C, and with no CO2 present, a saturated solution contains between 6.1 mg/L and 7.7 mg/L of CaCO3 (there are a couple of different forms with slightly different solubilities)

Calcium carbonate in water that is also saturated with CO2 combines with the CO2 and H2O and becomes calcium bicarbonate, Ca(HCO3)2, which is much more soluble.

Its solubility then goes up to 166,000 mg/L.

Incidentally, that's why I don't trust calcium carbonate to be a buffer, its sneaky. It changes its solubility by as much as 24,000 times according to how much CO2 is dissolved in the water. Koi keepers obviously don't have water saturated with CO2 but there will always be some present depending on numbers of fish, photosynthesis of plants or algae and the level of aeration that will be trying to drive the CO2 out and the actual level of CO2 greatly affects its solubility or ability to buffer pH changes.

Sodium bicarbonate is much better behaved and has a solubility in the region of 8.6 gm/L (8,6000 mg/L) at 20C.

So KH can have a saturation point that could easily be 8,600 mg/L (480 dKH) under normal koi pond conditions and could theoretically go as high as 166,000 mg/L (9,200 dKH) if the water was saturated with CO2.

Like Duncan, I'm not sure where on that scale of KH the lethal dose for koi would be but I'm certain you would kill them long before you reached anything like 480 dKH.