# Is it chlorine toxicity ?



## kekon (Aug 1, 2005)

I began to reconstitute pure RO water with CaCl2, MgSO4, CaSO4 and NaHCO3. I did 2 water changes (50%) of my 200 L tank and noticed that some plants look exactly like this:

http://www.aquaticplantcentral.com/...ine-toxicity.html?highlight=chlorine+toxicity

Ca is 25 ppm (20 ppm from CaCl2, 5 ppm Ca from CaSO4, KH = 3)
I'm not sure but it seems it could be too much Cl in the water. What do you think ?


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## RTR (Oct 28, 2005)

Chlorine is a dissolved gas (Cl2), chloride is dissolved anion (Cl-). Same element, radically different form and behavior/activity.


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## kekon (Aug 1, 2005)

I suppose it is caused by too much K. I've measured it recently in lab and it turned out it is 28,4 ppm K (lefs begin to curl). I have this symptom again.


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## Edward (May 25, 2004)

20 ppm from CaCl2 is fine. Where is the K coming from?


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## kekon (Aug 1, 2005)

K came from KNO3 and K2SO4. I know that you and T.Barr don't agree with me that too much K doesn't harm but I ran the experiment two times (when K level exceeded 20 ppm) and it gave the same results - leaves got horribly deformed. Rotala Rotundifolia and Bacopa Caroliniana don't grow at all.
After limiting K to about 10 ppm plants look much better. Now I have started to add K only during 50% water changes (10 ppm). I use only RO water and recently I have reconstituted it as follows:

20 ppm Ca from CaCl2 (it also adds 35 Cl - it may be too much)
5 ppm Ca from CaSO4
KH = 3 (from NaHCO3) (it also adds about 12 ppm Na - doesn't it harm ?)
5 ppm Mg (from MgSO4)

I order to limit Cl level I changed my recipe to:

15 ppm Ca from CaCl2 (it adds about 25 ppm Cl - maybe it's still too much)
10 ppm Ca from CaSO4
KH = 3
5 ppm Mg

I did 50% water change on Saturday using the recipe above but I will probably have to wait 2..3 weeks to see the effects. On the whole, things go better when Ca is higher. In the past I had 13 ppm Ca and 4 ppm Mg. The question is what effects Cl and Na levels will have on plants ? The chlorine toxicity as shown in the picture appeared only on 3..4 leaves. I tried to use CaCO3 but it is extremely difficult to dissolve even in water highly enriched in CO2. I also ground it by means of coffee mill to obtain smaller seeds to make it dissolve better  (but it didn't help much).
I'm thinking of giving more Ca from CaSO4 (much better water-soluble) and less from CaCl2 (to limit Cl to 20 ppm) but it could add too much SO4. 
The good thing is I have very little algae after increasing PO4 to 1 ppm (from 0.1 ppm) and NO3 to 10 ppm (from 2.5 ppm)


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