mysterious readings

[rhuffie]

Hello,
When I test my spa water for santizer using the little plastic unit that came with the tester, the water stays clear, indicating there is no sanitizer present. But if i put a drop of the testing fluid directly into the spa itself, it see a strong yellow?!
What gives?

 

[brajgreg]

Hello,
When I test my spa water for santizer using the little plastic unit that came with the tester, the water stays clear, indicating there is no sanitizer present. But if i put a drop of the testing fluid directly into the spa itself, it see a strong yellow?!
What gives?

What tester are you using?

 

[JamesW]

Probably so high that it's bleaching out. You need a fasdpd test.

 

[rhuffie]

it's from Leslie's, a large chain out here.
The chemical included in the kit is called orthotolidine

 

[JamesW]

OTO doesn't normally bleach out unless the bromine or chlorine level is super high.

Get a water sample and dilute it by adding an equal amount of distilled water. Mix well and then test the sample.

 

[rhuffie]

Ok, i think this is a classic newbie move.
While i did own and maintain a spa for many years, i think i forgot to wait long enough after adding the shock.
Now it tests fine.
How long should I wait, with the pump circulating (not on low), for the chemical to mix in and be ready for testing?

 

[ant 83]

Well if the chlorine is in a solid form, it can take a while to mix in. Liquid chlorine mixes right in. I usually wait about a minute with pumps on to test again when I have a bottle with a different date on it.

For the record, trouble free pool methods call for powder and drop to test chlorine levels. The yellow test block that only goes up to 5 FC is a waste of your time/effort.

I bought this kit not long ago:
FAS/DPD Chlorine CC's test

Has what you need.