water testing

[Neenie]

I have been testing my water using both test strips and a liquid testing kit. When I use the test strips they indicate that my chlorine level is very low, but when I use the liquid testing kit, it show that my chlorine level is okay or even a little high. Why am I getting two different readings? Thank you for your help. Janeen

ps. The test strips also show my ph is a little low, but the liquid test kit shows my ph is normal.

[Watermom]

We don't call them 'guess-strips' for nothing! ;) What kind of drops-based test kit do you have? What are your current readings? tell us about your pool.

Welcome to the Pool Forum!

[Neenie]

We have a 27" above ground pool, about 9 years old. I have always just used the test strips until I started reading on the website, Pool Solutions last year. I just bought a liquid test kit from Ace. It only tests for ph and chlorine. Last time I tested which was yesterday the chlorine level showed pink (normal) and the ph was dark gold (normal). I can be more specific when I test again tomorrow. thanks

[Watermom]

There is a lot more to know about your water than just chlorine and pH. We always recommend that people buy the Taylor K2006 or 2006C test kit as it is the best one out there. It is not available locally but you can get it through the test kit link in my signature above. (Takes you to Amazon.)

I think you have your colors reversed in your description above; pH is a pink scale and chlorine is a yellow scale in an OTO/Phenol Red kit (yellow and red drops) that I assume you have.

[PoolDoc]

OTO is a reliable test -- not super accurate, but very reliable. However it tests for TOTAL chlorine (free chlorine + combined chlorine).

DPD color match testing is NOT reliable: at levels above 5 ppm, the reading may begin to decrease, reading ZERO somewhere around 15 ppm. BUT, DPD tests for FREE chlorine only, without a 2nd added step.

Most color strips are yellow=>purple syringaldazine, which usually tests for free chlorine, which really only reads to about 5 - 7 ppm. It doesn't bleach out like DPD, but water with 8, 15, 30 ppm of chlorine will all three produce identical readings.

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