Why the need to test FC above 10 ppm?

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The k2006 without the *C* has much smaller bottles. (2.7X less IIRC). The larger kit reagents (TF100, TFpro, K2006C) go on sale each spring in the mid $40s at tftestkits.net. it's a no brainer to just get the set.

Individual parts always cost most than the thing you're fixing. You could build a replacement refrigerator from the repair parts, but it would cost several times more than letting Samsung (etc) do it.
 
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The only reagents I go through yearly are the OTO and Phenol Red. The rest of the kit I replace every other year with a refill kit when they go on sale from TFTestkits. I've yet to run out of anything else. Dave really did a good job of sizing the bottles to the amount of use they are needed over the two year life span when he created the kit.
 
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Trying to understand CYA further, am I saying it correctly that once my CYA levels reach ~20 in my swim spa that my old FC level reading of 3 ppm without CYA will be obsolete?

I read "How do I use Chlorine in my Spa or Hot Tub?" and Chlorine/CYA relationship articles but dont fully understand.
How do I use Chlorine in my Spa or Hot Tub?


I've been maintaining my swim spa FC at 3 ppm, CYA still at 0.0 because its a new fill, and im testing every day with K-2006.

So, once my CYA hits 20, should I expect to obtain much higher FC readings? Could I have a safe FC reading of 3 ppm with a CYA level of 20?

I feel like this is the last thing I need to figure out and then I should be good to go.

Thank you.
 
swimmynoodle said:
So, once my CYA hits 20, should I expect to obtain much higher FC readings?
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Yes.

Min FC is 2 for 20 CYA, plus UV loss, plus bather load.

Target range gets blown out of the water in a hot tub / small pool based upon use. If you take a couple soaks today you'll likely need to dose a couple times. And maybe for redisuals tomorrow.

lc_chart.jpg
 

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Newdude said:
Yes.

Min FC is 2 for 20 CYA, plus UV loss, plus bather load.

Target range gets blown out of the water in a hot tub / small pool based upon use. If you take a couple soaks today you'll likely need to dose a couple times. And maybe for redisuals tomorrow.

View attachment 607130
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Thank you. If we have to also test for CYA, arent we going to blow through CYA reagents? They dont give much in the test kits.
 
For a reason. :) once you dial it in, it mostly won't change unless you add more or refill a bunch of water. So it's a monthly test, maybe longer.
 
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I researched OCLT on TFP so that I dont repeat the question. I did the OCLT on my swim spa last night, cover was on (not that it matters at night), temp @ .80F.
Before Test @ 9pm (K-2006):
FC 3
CC .5
TC 3.5
TA 60
pH 7.5
CH 60
CYA 0 Didn’t test yet; waiting for dichlor to build up more to save reagents.

After test @ 9am:
Everything stayed the same expect FC went down to 2.5. Water is clear and looking great. I have not been in it for two days.

According to OCLT, .5 is a passing score. My question is, I read on TFP that chlorine needs to be replenished constantly; its just the nature of the beast. Is it simply an acceptable, understood chemical process that FC will simply drop (even in a covered swim spa protected from UV rays 99% of the time) and that I will need to add small amounts of chlorine (dichlor/liquid to prevent CYA rise) every couple of days, even if I don't go for a swim?

Thank you. TFP is the place to be. I feel so knowledgeable knowing all of these terms now :cool:🤓
 

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swimmynoodle said:
Is it simply an acceptable, understood chemical process that FC will simply drop (even in a covered swim spa protected from UV rays 99% of the time) and that I will need to add small amounts of chlorine (dichlor/liquid to prevent CYA rise) every couple of days, even if I don't go for a swim?
:cool:🤓
Click to expand...

Yes.
 
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Towards the top, the article says, "Though using no CYA results in the least amount of chlorine loss, the fact is that you simply can't maintain a pool with only 0.05 ppm chlorine everywhere in it -- hence a minimum level is needed as a buffer."

Does this mean in a swim spa, covered from the sun 99% of the time, I technically don't need to worry about CYA levels and CYA levels with the relationship of FC?

Thanks
 
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swimmynoodle said:
Does this mean in a swim spa, covered from the sun 99% of the time, I technically don't need to worry about CYA levels and CYA levels with the relationship of FC?
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Chlorinated water without CYA is very harsh even at low FC levels.

Any chlorinated water you swim in should have at least 20-30 ppm of CYA to buffer the chlorine harshness.
 
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ajw22 said:
Chlorinated water without CYA is very harsh even at low FC levels.

Any chlorinated water you swim in should have at least 20-30 ppm of CYA to buffer the chlorine harshness.
Click to expand...

Thank you for the information. If you could assist with the following question(s) I would appreciate it greatly.

1. Swim spa temp was 84F earlier today. I raised it to 90F and pH levels went from 7.5 to high off the charts hours later. I assume a correlation between temperature increase and pH rise due to warmer temp > dissolved gasses > aeration > pH rise. Should I expect it to be normal to have to add Muriatic acid more often while swim spa temps are higher to keep pH levels in check (lower)?

2. I need to get my CYA level to 30 ppm but its taking forever. I add about .12 oz dichlor every couple of days to maintain FC @ 3ppm. At that rate its going to take me weeks. Can I throw in a bunch of dichlor (I would measure how much I need to get CYA levels to 30), raise my FC levels really high to get CYA levels up, and then use hydrogen peroxide to neutralize/lower FC levels back down to appropriate levels?

Thank you!

Current levels (K-2006)
FC 3 ppm (15 drops x 0.2). Also performed 0.5 test with same results.
CC .2
TC 3.2
TA 60
pH Waaay off the charts. Dark red. 12? 14?
CH 60
CYA ~10. Performed drop test. Cloudy, but could still see black dot @ 20. Estimating 10 right now.
 
Use dry stabilizer to get your CYA up. Add it with the sock method.

Temperature does not affect pH. Aeration will cause pH to rise.
 
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ajw22 said:
Use dry stabilizer to get your CYA up. Add it with the sock method.

Temperature does not affect pH. Aeration will cause pH to rise.
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Oooh right, I forgot about the waterfalls and jets I ran. That for sure raised the pH. Thanks!

When you say dry stabilizer, do you have a dry CYA product recommendation? I know TFP does not like Clorox products.
 

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