Inconsistent FC results

[Bluelilly]

I tested water this a.m. Using daily test and results were somewhere between 4-5 (deep yellow) which is good but also tested using FAS/DPD and results were about 2.5. The R-0870 is new but the R-0871 was purchased last year so was the R-0600. All stored inside so they don't get too hot.

Is there something that I am doing wrong or do I just need to adjust IC to produce more chlorine based on drop test

FC. 4. Or 2.5?
CC. O
CYA 60 (need to bring up a bit)
pH. 7.6
TA. 70
Water temp around 78

I don't want the FC too high but definitely not to low so not sure what I should adjust output based on.

Thanks!

 

[tim5055]

Did you do a CC test when you did the FAS/DPD?

The FAS/DPD reads FC, the OTO reads TOTAL chlorine. Could you have 1.5 CC? Remember, FC + CC = TC

Even if your CC is between 0.5 - 1.0 I would say the numbers are close.

Trust your FAS/DPD numbers

 

[jblizzle]

The yellow matching is pretty difficult, trust the FAS-DPD.

And it appears it is a good bit low based on your CYA level.

 

[Bluelilly]

The yellow matching is pretty difficult, trust the FAS-DPD.

And it appears it is a good bit low based on your CYA level.

Thanks, that was what I was thinking. Bumping IC output up to get to at least FC of 4

 

[Richard320]

My experience, based on comparing the two tests, is that anything between 4 and 7 looks like 5 on the OTO test.

So what's it good for? Right now, I'm in the enviable position where minimum FC is 4... So as long as the OTO test looks at least as dark as the highest color sample, I'm good.

 

[Bluelilly]

My experience, based on comparing the two tests, is that anything between 4 and 7 looks like 5 on the OTO test.

So what's it good for? Right now, I'm in the enviable position where minimum FC is 4... So as long as the OTO test looks at least as dark as the highest color sample, I'm good.

I very seldom use the OTO and just use FAS/DPD but this morning thought I would do both and compare as I had been checking levels,with OTO this week. I won't say I am paranoid about an algae outbreak but I really do not have the time to deal with it if it should happen . All that to say, the low reading on the FAS/DPD and normal on the OTO caused me to have an "uh oh" moment as 2.5 was not what I was hoping for. I do try to keep 4-5 based on current CYA. So, I guess the conclusion is trust the FAS/DPD.

Thanks!