Is CYA too high?

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D

dozer11

Well-known member
Jun 2, 2014
98
Thompson, ND
I've been using chlorine granules from pool store. I just got my refill of CYA reagent in the mail and did a complete test and here are the results from the Taylor k2006

FC .5
CC .5
TA 60
PH 7.4
CYA 90
CH 110

My question is: can I/should I start using bleach now as my sanitizer or is my CYA too high? This would be my first time using the bleach method and might need a little hand holding. Also, when the jets are running the spa is a little foamy.
 
If the pool is crystal clear, you could maintain the right FC level for your CYA and keep your fingers crossed. Check my explanation in this thread from earlier today. The same applies to you, just not as much, since your CYA isn't as bad.

The foam in the spa is probably due to the low CH. You can raise it with some Ice Melt. I'm sure you all know what that is up in North Dakota! Pool School - Recommended Pool Chemicals
 
Is the chart for FC reference CYA levels for pools and hot tubs? Or is a higher FC level required for hot tubs vs. pools? I can do a partial drain next week so that isn't too big of a deal. I'm just brand spanking new to all this and want to make sure I understand it completely before dumping bleach into my hot tub. (My husband is a Debbie doubter)
 
With a separate hot tub you do not follow the chlorine/CYA chart because the chlorine demand is largely determined by bather load and the hotter water temperature has more active chlorine at the same FC/CYA ratio and the covered hot tub usually does not get algae.

So instead the rule is to add whatever amount of chlorine is needed after a soak such that you still have a residual 24 hours later and then maintain that residual until your next soak. Normally we suggest a CYA of around 30-40 ppm and most people prefer to start their soak with around 1-2 ppm FC. The FC level in between soaks should not be lower than this though it can be higher if you like (to last a bit longer) but probably not much more than 4 ppm.

In your case with the higher 90 ppm CYA, I'd keep the FC level at 5 ppm until just before your next soak at which point you can lower it to around 2 ppm if you like (letting it drop which is usually around 25% per day unless you have an ozonator in which case the drop is usually 50% or more per day).

For the foam, just scoop it from the surface. It may be from soap in your swimsuit so be sure to rinse it out thoroughly before using the spa. You should be able to use bleach at this point until your water gets too dull or the chlorine demand rises too much. For your next water change, use the Dichlor-then-bleach method to prevent the CYA from rising as much. See the Pool School article and sticky in this spa forum Using Chlorine in a Spa.

Note that when you switch to bleach (even now) you'll want your TA to be lower closer to 50 ppm and you should add 50 ppm Borates (usually from boric acid) for additional pH buffering. Otherwise, your pH may rise too much from aeration (especially from spa jets).
 
In your case with the higher 90 ppm CYA, I'd keep the FC level at 5 ppm until just before your next soak at which point you can lower it to around 2 ppm if you like (letting it drop which is usually around 25% per day unless you have an ozonator in which case the drop is usually 50% or more per day).

I can keep it at 5 ppm of FC. My question is- how do I lower it to 2 ppm just before my next soak? My husband and I use it regularly- about 5 times per week- also- my CC jumped to 1 after my first addition of 3 oz of bleach to get FC to 7- which is what that chart recommended- now I know not to use the chart. Do I need to shock the hot tub to get rid of the CC?
 
You can let it drop in the days before the soak, perhaps 3 days depending on how quickly it drops or if you want to explicitly force it down you can add hydrogen peroxide as a reducing agent. It takes 1-1/2 tablespoons (4-1/2 teaspoons) of 3% hydrogen peroxide to lower the FC by 1 ppm in your 360 gallon spa so to lower by 3 it would take 4-1/2 tablespoons of 3% hydrogen peroxide.
 
I've decided to wait on the drain and re-fill and just deal with the higher CYA for now. I have a question about combined chlorine. My test results from today are

FC 1.5
CC between 1 and 1.5
PH 7.4
TA 70
CYA 90
CH 110

How do I get rid of the CC? I've been using bleach as my only sanitizer for about 2 weeks now. Everything seems to be going good except the combined chlorine. At what CC level is it harmful for people?
 

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If you used any non-chlorine shock (MPS) then that can show up as CC (or as FC depending on the type of test you are using).

If you tested soon after a soak, then the CC will be higher and that's normal since it represents bather waste in the process of getting oxidized by chlorine. If you are measuring this level of CC just before your soak and this is at least (roughly) 24 hours after your last soak and dose, then that's higher than normal. It may be due to your higher CYA which will make the FC you added slower to oxidize the bather waste. That's why I recommend a CYA level of around 30-40 ppm since that seems to be about right to be able to keep up with oxidizing bather waste.

If the CC doesn't smell objectionable, then it's probably OK. Odds are it's monochlorourea which is not a problem (urea is the largest nitrogenous chemical in sweat and urine). If it smells like "bad pool smell", then it may be an inorganic chloramine instead though realistically that should get dealt with in the hours after your dosing even with a CYA of 90 ppm. So bottom line, if it does not smell objectionable, just live with this until your next water change and let us know if this still happens with a normal CYA level at that time.
 
I haven't used any MPS so it wasn't that. It was roughly 18 hours after 2 people took a soak, and I tested the CC last night and it was less than 1. So, the issue may have been the higher CYA was slower to oxidize the waste as you pointed out. Thanks for the help. The smell isn't terrible, but I definitely smell chlorine when I open the cover. I'll keep my eye on it in the next few days.
 
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