Calcium and Copper tests

[Tom007]

Last year my calcium test said 250, using the Taylor test kit drop test. Since it remained constant I did not bother to test it regularly. I then added some copper algecide last summer. Now my calcium test says 190. I followed the instructions here to modify the test for copper in the water and got the same results:

http://www.taylortechnologies.com/Ch...P?ContentID=70

I don't have a copper test here at home but the pool store test said no copper.

I have two questions -
1. What is going on with my calcium test results?
2. When you add a copper algecide to the pool does the copper stay there forever?
3. Is there anything that causes calcium to go down over time?

[Tom007]

I haven't gotten an answer to this yet. Is it because the question is poorly worded and hard to understand? Is it because in some way it is a dumb question? Or is it just because no one knows the answer?

[waterbear]

Last year my calcium test said 250, using the Taylor test kit drop test. Since it remained constant I did not bother to test it regularly. I then added some copper algecide last summer. Now my calcium test says 190. I followed the instructions here to modify the test for copper in the water and got the same results:

http://www.taylortechnologies.com/Ch...P?ContentID=70

I don't have a copper test here at home but the pool store test said no copper.

I have two questions -
1. What is going on with my calcium test results?
Probably nothing at all. Your calcium level dropped. There are several things that can cause this. Most common are a pH spike and higher TA levels causing calcium carbonate to precipitate out or dilution from lower calcium water (such as rainwater). Calcium levels can and do fluctuate!

2. When you add a copper algecide to the pool does the copper stay there forever?
Until it deposita as stain on pool surfaces, filters, or people! Chelated copper tends to stay around for about 3 months. Inorganic copper (copper sulfate) maybe a month. Copper is what turns hair green. If it staina out on pool surfaces then lower pH can cause it to redissolve back into solution.

3. Is there anything that causes calcium to go down over time?

That's THREE quesitons!
Yes, calcium levels can and do fluctuate over time. In some areas the calcium level in the fill water change during the year or with the water table, dilution from rainwater can lower calcium levels, calcium can precipitate out as scale and either deposit on pool surfaces or in the filter when there is a pH spike for whatever reason or when TA is increased (often, but not always, accompanied by cloudy water).
Finally, the calcium hardness titration is often done incorrectly. This is a slow test if there is a high calcium hardness level and you should either be using a magnetic stirrer or swirling teh sameple for about 20 seconds or so AFTER EACH DROP of titrant is added and KEEP ADDING TITRANT UNTIL ONE ADDITIONAL DROP PRODUCES NO FURTHER COLOR CHANGE!). I prefer to use the smaller 10 ml sample size which has a resolution of 25 ppm calcium to get an idea of whatcalcium is since the color change is more distinct and then retitrate with the 25 ml sample size since I now have a ballpark figure of where the color change should occur and can keep a lookout when I am approacing it. Instructions for the 10 ml sample size test are in small print on the lid of the K-2006 test kit at the bottom of the calcium hardness test section.

[Tom007]

Thanks for your help waterbear. I'll do the test as you suggest.