New spa low, constant low fc readings?

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mxfan

mxfan

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LifeTime Supporter
Jul 24, 2008
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Shingle Springs, CA
I'm a new spa owner, purchased a Sundance spa that was on display at a home show and the spa has 'clearray' purification system.
We've had the spa approx. 4 weeks and I am constantly finding 0 fc readings. I have had a salt water pool in the past, so I am somewhat familiar with the chemical process. I have been reading in the forum and pool school about how different spa chemistry is and I'm a little confused. The owner of the store I bought our spa from briefly went over the chemistry, and gave me a small supply of chemicals that they recommended.
I here are my current test numbers as of this morning: Note that I added 'spa chlorine' 2 days ago and brought the FC level up to 10. So in just 2-3 days with no use of the spa it dropped to 0 fc.

FC 0
PH 7.8
TA 80
CH 280
CYA 35
Temp 101

The owner also recommended throwing in a couple teaspoons of 'spa oxidizing shock' after every use which we have been doing.

I have been reading about changing to liquid chlorine or bleach, but I am not sure what I should do or where to start?

Thak you for your time!
 
Start here: How do I use Chlorine in my Spa (or pool)?)

With your CYA at 35 you'll want to stop using dichlor as you have been using and switch to bleach now. Check your FC daily and add as needed. With my last fill in mid January it took just over a week to add enough dichlor to get the CYA to 30, so if it's taken you a month to get to 35 you're really not adding enough chlorine.

Dropping from 10 ppm to zero in two days does seem a little fast. My guess is that because you've let it drop repeatedly to zero waste isn't getting oxidized completely and is building up or something is growing. Just get the FC up to shock range, then allow to drop to the proper range and keep it there by daily checks and chlorine additions. Once you track it for a few weeks to a month you might get the hang of it and can start checking every other day or so. Proper FC ranges are in the chart below. For a CYA of 35 shock is 14 ppm and target range is around 6 ppm.

Pool School - Chlorine / CYA Chart
 
Once your water is balanced and you have moved to liquid bleach, be sure to test your CYA levels at minimum once every three weeks until you learn your system, as the CYA will move lower much faster than a pool. Easy to switch to back to dichlor until your CYA is 30-40 ppm. We also use 1oz of 10% bleach for each bather added after we are done. Another important test is the CC, combined chlorine as it will rise over time if the spa is covered after use. Uncovering the spa will help slowly lower the CC but when it gets too high you are nearing the clean, drain, flush and refill stage of spa maintenance in my opinion. Our spa is 250 gallons and during peak use we clean and refill after 75 days now.
 
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