ph mystery

[sspine]

I need some help. Have been using exclusively BBB method for 3 years with Taylor test kit. Pool has never been cloudy since switching. It is so easy, that I have gotten lax with testing. We basically add 1 Walmart bleach a night.

Last night tested cl only , it was at 2ppm; added large bottle of bleach. I had not checked ph (which typically stays between 7.5-7.7) due to being out of phenol red. When I tested the ph, it was a pale pink. It looks like the 1ppm on the chlorine scale.

Here are today's complete results. I would appreciate your input. This website has been so informative. Thank you all for such great information.

16x36 ig vinyl
CL 1
fcl 1.5
ph ? new phenol red and it is a very pale pink
Alk 250
cya 30

[aylad]

Sounds like you have an algae bloom trying to happen. With a CYA of 30, you should keep a minimum of 3 ppm chlorine, and try to target 3-6. If your chlorine has been less than 3 for any length of time, especially during this hot weather, that would explain the cloudy water. I would shock the pool up to 15 while running your filter overnight, and I think you'll see it clearing up.

I'm not sure I'm understanding the problem with the pH measurement.....are you using the OTO test either from WalMart or from Ben's kit? On my OTO block, the pH is measured in pink to purple colors, and the chlorine is measured in shades of yellow. On my OTO block, a light pink pH would be in the 7.3-7.5 neighborhood. When you replaced your reagent, did you get the right reagent for your block? There is an R-0004 and an R-0014 that are not interchangeable.

Hope this helps....

Janet

[sspine]

Thanks, Janet. I use the Taylor kit, but this phenol red I picked up is from Walmart. My Taylor kit shows ph from yellow to fushia, no pastel shades. This is very pale.
Could this be the problem

The water looks great. The other thing I didn't add, was temperature:85.

[aylad]

I'd be willing to bet that you have the wrong reagent. Check the number on your old bottle...the stuff that comes from WalMart is R-0014.

Janet

[sspine]

The Taylor is 04, the hth just says Phenol red. I will get to the pool store and see if that is the answer.

With a vinyl pool, do I need to get that alkalinity down?

I will post later this weekend when I get the new reagent.

[chem geek]

Assuming your Calcium Hardness (CH) is around 150 ppm or lower (you should test it to see what it is even though you don't need it to be high), then the only problem with the high Total Alkalinity (TA) of 250 ppm would be a tendency for the pH to rise over time. If you use a pool cover regularly you may not notice that.

As for the pH reagent, you generally want to use the proper reagent for the pH test you have since the blocks are calibrated in color for that reagent. Phenol red produces standard colors so you could add more of the reagent you have to make it more intense, but the reagent also has other chemicals (like thiosulfate) to neutralize chlorine that can interfere with the test. Such extra chemicals can affect the ph reading a little.

Richard