closing pool for summer break

[Jacko19]

Hi - I have to leave France for a couple of weeks and cannot leave my filter running - I will be fitting the security cover which is heavy tarp and should keep out the light. Have had heavy thunder storms and heavy rain in last couple of days so am working on getting the pool right at the moment - no green but an opaque blue. Will be shopping for bleach and baking soda this afternoon as I have the below results.
The water temp currently around 29c and we have full sun from midday until sundown.

clf 0.45
clt 0.27
ph 7.71
cya 3 (this has dropped dramatically)
ta (my tester range says 10-500 mg/l) and the result comes up as low - inferring less than 10?

Assuming that I get the figures in the right ball park what should I do when I leave it - elevate the Chlorine level

My pool – 55 cubic metres capacity,spectacle shape i.e. 2*6 metre circles joined together to make 9.5 metre long – 1 at 1 metre deep and 1 at 1.8 deep,Pool chemicals - chlorine shock and 9% bleach
My pump & filter Deyjouye setup with fabric filter bag
Using Scuba + test kit

 

[BoDarville]

Welcome to TFP!

clf 0.45
clt 0.27
ph 7.71
cya 3 (this has dropped dramatically)

I'm a bit confused on all the test results (except for pH). The chlorine and CYA results are measured in parts per million (ppm). If the clf and clt indicate free chlorine (clf) and total chlorine (clt), the clt should be equal to or greater than clf. In either case, both appear low if measured in ppm. Also, a CYA of 3 is highly suspect. If not measured in ppm, what is the unit of measure used to come up with this result? Are you using a view tube to measure? All view tubes that I am aware of do not go below 20 ppm. If the black dot is visible after pouring in the water / CYA reagent mix, then CYA is less than 20.

If running the pump is not an option, the best thing you can do is dose with liquid bleach up to shock level for your CYA (but we need a better understanding of what the true CYA level is) and then put the cover on. The cover will keep sunlight off the pool and reduce chlorine loss. However, given that your pool water seems to be a bit cloudy, it is likely you will have to shock when you return.

Would suggest looking at the following articles to get a better understanding of the chlorine/CYA relationship: ABC's of Pool Water Chemistry, Chlorine CYA Chart.

 

[msgtdan]

Welcome

Where in France?

According to a conversion program I have ppm is mg/lt so the TA number would indicate less than 10. Doesn't sound right. Pool volume would be about 14.5k. What type of test kit? The numbers don't really make sense, to precise if ppm for most pool tests.

 

[JohnN]

Just to add on, I believe it is impossible for pH to be 7.7 with a TA of 10 or less.

 

[jblizzle]

Ah don't you love the highly accurate results from digital testers I would not believe any of those numbers.