no chlorine

[chem geek]

I'm sorry I confused you. Cal-Hypo does NOT add CYA to the water. It only adds to CH. It is Trichlor and Dichlor that add CYA to the water. So yes, you can continue to use Cal-Hypo and monitor the CH to make sure it doesn't get too high.

I'm surprised there is no test kit in Australia that tests for CYA. I found this site in Australia that sells Taylor kits and at least has the K2005C, but ask them if they have the K-2006 (A or C) as the FAS-DPD chlorine test in the K-2006 is better.

As for whether chlorine is effective at your higher CYA, the answer is yes, it is always having some effect. It's just that at higher CYA levels it takes a higher FC level to have the same effect and at some point algae can grow faster than the chlorine kills it. Since your water is clear and you are not seeing unusual chlorine demand (drop in FC overnight) then you are in good shape so don't worry about it.

You can manage water where you are using stabilized chlorine such as Trichlor by either regularly diluting it or by using a supplemental algaecide such as PolyQuat 60 or a phosphate remover in maintenance mode, both on a weekly basis. It's more expensive, but will ensure you don't get algae. At some point, though, you do want to know the CYA level since the TA level needs to climb to maintain proper saturation of the water to protect plaster/concrete surfaces. You can determine the saturation index at The Pool Calculator link I gave earlier. If the index is very negative, then the water has the potential to etch plaster/concrete. It's a rough index of potential, however, so don't sweat it if it's just -0.3 or something like that. If it's below -0.6 or so, then look at increasing it. You've already been adding Calcium Hardness (CH) via the Cal-Hypo so are on the right track. I usually target my pool at around -0.2 to -0.1 so that in the gas heater it doesn't get over-saturated (higher temperatures can precipitate scale).

Richard

[Fabianj]

I opened my pool on May 6th. The water was dirty but cleaned up after 3 days by running the filter 24/7 and adding liquid shock to the water along with an algacide that the pool store said I should use.

My problem is that I can't get a free chlorine reading on my test strips.

I have taken a water sample to the pool store on two different occasions (May 9th and May 21st). The first time the water showed readings of:

May 9th readings
Free Chlorine: 1.1 ppm
Total Chlorine: 4.2 ppm
Combined Chlorine: 3.1 ppm
pH level: 7.3
Hardness: 120 ppm
Alkalinity: 134 ppm
Cynuric Acid: 55 ppm

May 21st readings
Free Chlorine: 0.2 ppm
Total Chlorine: 3.1 ppm
Combined Chlorine: 2.9 ppm
pH level: 7.8
Hardness: 90 ppm
Alkalinity: 102 ppm
Cynuric Acid: 60 ppm

Why would the level be zero on the test strips when I am using chlorine through the chlorinator at a rate of 5 3" tablets per week?[/b]

[jemae]

Thank you for all your help. Been queit for a while monitoring my pool readings after i got back fr perth with all the stuff. All the readings is stable.

Total chlorine 4
free chlorine 3
total alkaly 80
ph 7.2
cya 30
total hardness 250

Hope it will stay that way. Also got zodiac g4. Quite good, besides it refuse to climb the stairs.

[chem geek]

I have taken a water sample to the pool store on two different occasions
:
:
Why would the level be zero on the test strips when I am using chlorine through the chlorinator at a rate of 5 3" tablets per week?[/b]

I wouldn't trust the pool store numbers. For test strips and DPD drop tests (the latter measuring intensity of pink/red), high chlorine levels can bleach out the test having you think there is no chlorine when there is a lot. The OTO test (measuring intensity of yellow) won't bleach out, but the best chlorine test is FAS-DPD where you count the drops and can measure up to 50 ppm. Get yourself a Taylor K-2006 test kit which you can get at a good online price here or the TF100 from tftestkits(dot)com here with the latter kit having 36% more volume of reagents so comparably priced "per test".

Your pool store tests say that the Total Chlorine is higher than the Free Chlorine which means you've got Combined Chlorine, but that is unusual in an outdoor pool exposed to sunlight unless you've got ammonia in the water or are fighting an algae bloom.