Test kit received I am intimidated - with results

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I am still new with TFP.
When are you testing your water? Is there rules for this? Should it be tested at the same time each time we do a test? Do you test it before or after you added chlorine?

Also, what is the best way to proceed to establish the correct daily chlorine addition for a usual day? I would like to add the chlorine mainly in the evening and would like to know what is the general rule to follow for my pool.

Thanks
 
It is best to test your water around the same time each day. Add your liquid chlorine after you test. You need the test to know how much to add.

On the days you simply cannot test, you add the amount of liquid chlorine, or maybe a bit more, that you usually add. Your pool will get you in a routine on how much it needs.
 
OK. Thanks everybody. As always, comments and advices are greatly appreciated.

Yesterday I did my CYA test after stabilizer addition on Sunday. I lost the dot between 30 and 40 so I rounded up to 40 as my CYA value as instructed by @mknauss

I did a basic test this evening. FC 6.5, CC 0.5, PH 8. According to the chart, I should target 5-7 based on CYA 40. I wanted to add some chlorine to reach the highest value. I prefer to be at the top of target. But later when I went to add chlorine I forgot to use the calculated value of Pool Math and by reflex I used the generic value I was used to before receiving my test kit. Final result is instead of adding 0.5 ppm of chlorine I added 2 ppm. I will be at around 8.5 instead of 6.5. Is this an issue since I busted the target? Will this harm something?

Also, I have a cover on the pool. It is mainly for the night. Is it OK if I leave the cover on the pool all day long and I remove it only when we get back from work? Is it a problem?

Thanks
 
Ok I am a bit worried with my test results. I did another full set of test yesterday and I think that my results are not bad at all except CYA where value is not what I expected it to be. I did a full test 2 weeks ago and I was doing chlorine and pH daily.

Here the results yesterday
FC 3.5
CC 0
pH 7.5
TA 125
CH 250
CYA < 20 (I really think that I was seeing the dot at 20)
TEMP 88
CSI 0.08

I am discouraged with the CYA because I am never confident on the result. 2 weeks ago I tested it and I added CYA with the sock method because it was below 30. When I retested after, I was between 30 and 40, near of 30, but as instructed I round to 40. Now I test CYA again and I am back to where I was? I don't understand. I backwashed once since my CYA addition. I was to go to the pool store to double check the results but I decided to abort the project.

But now what I should do? Am I doing things wrong? I think that I am careful with all the tests so I don't know what I can do wrong. Even careful, I find that it is always difficult to say the result. I am still not confident with that test and I don't understand what get me to that result.

Should I add more CYA with the sock method? I see no other options but I don't want to harm anything. What else?

Any chemist here could invent a CYA color change test similar to what we have for other tests? I think that it could be a good business opportunity.

Thanks for your help.
 
Add another 10 ppm worth of CYA. Assume for your FC that you have 40 ppm CYA.
After the CYA if fully dissolved from the sock, wait 48 hours and test CYA again.
When you do the CYA test, try this next time.

Once you have your solution ready, back to the sun, etc. Fill the vial to a line, say 80, lower the vial to your waist level and glance for the dot, you see it, add solution to the 70 line, glance, see it, repeat until you no longer see it with a glance. Then use the CYA value one step above the line you read. So if you stopped at 50, use 60 ppm CYA.

The vial is in logarithmic scale. So it is not viable to interpolate between the lines. Just use the whole numbers, such as 50, 40, 30, ....
 
@mknauss Thanks a lot
I also try this advice that I saw many times in posts but no luck as I still get the same results.

Do you think that the situation is normal? Is it something possible? If CYA does not disappear itself is it normal to be back to where I was? I refilled after my backwash and there was some rain but I was under the impression that CYA was more resistant.
 

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Backwash and overflow will reduce the CYA level in the pool. Also the test is very susceptible to the conditions you test in. Best to do the test in full sun, back to the sun, etc. Also once you get a result, pour the solution back into the bottle and do the test several times to confirm what you saw. The test itself is at best +/-10 ppm.
 
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Also, just to confirm I understand correctly.
On my full test 2 weeks ago, TA was 125 and CH was 250. I used 10ml sample.

When I did the test yesterday, I got the same results for TA and CH.

Am I correct saying that they may not be exactly the same value and they may be lower because of acid addition and dilution but they are in the range 100-125 for TA and 225-250 for CH ?
 
The TA and CH can be the same. Only the TA would have been effected by any acid addition. And it may not have been enough to effect it appreciably. Also, if your fill water is high in TA, if you added water due to evaporation, that will add some TA to counteract any reduction due to the acid.
 
Like I do almost each evening I tested my water for chlorine. I have a weird situation. Is it possible that I lost no chlorine or not enough for it to be significant?

My CYA is 40. Water temperature 85.
I have a cover and pool was covered all day. It was mainly cloudy today. If I take my FC result of yesterday and add the ppm of the chlorine addition I did yesterday I get a value and tonight I have an FC at this value.

Someone already get this situation?
 
Ok thanks.

I have another question. I don’t know how to explain it exactly.

When you fill a cylinder, vial, bottle, etc and you are looking for a measurement, there is often a kind of circular surface that is created on the top of the liquid. I don’t know what it is it seems a kind of halo. Hope you can understand what I mean. So when we look for a measure, should the level be above or under it?
 

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