Chemicals and levels for new Catalina 16' SwimSpa (2000 gallons)

[Wolf5]

Hello - First-time poster!
Questions below, and here is the backstory.
My new swimspa (Catalina 16', 2000 gal) was just installed a few days ago, and I'm going nuts over here about the levels. We filled it up, and the levels were:
FC: 0
PH: 8.5+
TA: 50
CH: 100
CYA: 0
Over the course of the day, I balanced the TA to 120 or so, lowered the PH to 7.2, and then added 1 cup of 10% liquid chlorine to raise the FC.
Next day, FC was still 0. I added another cup of liquid chlorine.
Later that same day, it was 0 again. We swam in the spa, and I added more chlorine (16 floz, I believe) to see if I can shock this sucker. 
Next morning, it's 0.
Apparently the UV filter is eliminating the FC, right?!
I was told by our dealer to shock the spa when we get it, and then we won't have to use chlorine anymore. I have serious doubts that we never have to use chlorine again. 
For now, I just want to know what the heck is going on.
QUESTIONS:
Is there a sweet spot of time after I add chlorine when the levels DO actually read on my testing strip?
Should I add chlorine outside of filter schedules and just run the jets to swirl it around?
I have no idea what to do. I just know I'm over-chlorinating my new beauty. 
Thank you very much. And please let me know if I've left out any data that will help in answering these questions.

[waterbear]

Have you purged? Have you added CYA (chlorine stabilizer)? How are you testing the water?

22 hours ago, Wolf5 said:

I was told by our dealer to shock the spa when we get it, and then we won't have to use chlorine anymore. I have serious doubts that we never have to use chlorine again. 

Do you have a SWCG? If you don't then you need to add chlorine manually. You need a FAST ACTING RESIDUAL sanitizer. UV is not residuall. You also need Stabilizer (cyanuric acid, CYA) at 30 to 50 ppm to prevent chlorine degradation from UV (usually from sunlight but your "UV filter" will do the same.

Since this is a swim spa the aeration from the jets will cause a faster pH rise because the aeration will outlast CO2 faster so youvwant your TA to be lower. Also, if you are using liquid chlorine or bleach (net pH neutral) for sanitation you want your TA lower than is you are using dichlor or trichlor (net pH acidic) you want your TA lower. I would start with TA in the 50 to 70 ppm range and keep the pH no lower than 7.6. Lower it when it goes ABOVE 7.8.

10 ozone of 10% bleach is nowhere near shock level, btw. 

If you are testing chlorine with DPD then be aware that DPD will bleach out at high FC levels and make you think you have no chlorine when, in reality, it's high. Also, be aware that high sanitizer levels will interfere with pH testing making you think the pH is very high when it is not. NEVER test pH if the FC is above 10 ppm (some tests this can be as low as 5 ppm depending on nanufacturer).

Finally, you said not post TC (or CC if using FAS-DPD testing for chlorine). This is an important parameter. 

Answer these questions and we can take it from there. 

[Wolf5]

Thanks, @waterbear! 

We filled it up initially, and have not emptied it (it's only been a week of having water in it).
I am testing with testing strips (AquaCheck 7-way). 
I have not added CYA yet, just Muriatic to bring down the PH initially.
We do not have a SWCG.
Here are my current levels, based on my AquaCheck strip just now:

• Total Hardness: 100
• Total Chlorine: 0
• Free Chlorine: 0
• PH: 7.0 (it's dipped down this week)
• Total Alkalinity: 80
• CYA: 0

The water is a bit cloudy today, FYI.

Sounds like I need to:

1. Raise the PH to 7.6.
2. Raise the CYA to 30-50 to stabilize the chlorine I add (currently just have liquid chlorine, not di or tri-chlor).

Questions:

1. How much liquid chlorine to add and how often?
2. Stick with liquid or change to di or tri-chlor that has the stabilizer in it?
3. With our UV filter, what level of chlorine should we stay at during the week? FC or TC, unsure which I'm asking about.

thanks so much!

[waterbear]

20 hours ago, Wolf5 said:

I am testing with testing strips (AquaCheck 7-way). 

Test strips are useless for water balancing. While they are precise (same results when doing multiple tests on the same sample) they are not accurate (the test results indicate the actual water parameter level).  Some of the tests have an accuracy of +/- 40 ppm which makes balancing some parameter impossible. Total hardness is a useless test since we are only interested in calcium hardness, which can't be done with a strip because of limitations in the chemistry used.,

Get a good test kit. I recommend the Taylor Technologies K-2006 which uses FAS-DPD testing for FC and CC (Does not bleach out at high sanitizer levels unlike DPD testing), pH with acid and base demand (useful for adjusting TA), TA, CH, and CYA. https://www.taylortechnologies.com/en/page/231/k-2006-complete-kit-with-fas-dpd

You can find this test kit online from many online pool supply stores and Amazon. Some local stores might carry it but usually only carry the K-2005 which uses DPD testing and is not what you want.

20 hours ago, Wolf5 said:

• Total Hardness: 100
• Total Chlorine: 0
• Free Chlorine: 0
• PH: 7.0 (it's dipped down this week)
• Total Alkalinity: 80
• CYA: 0

The water is a bit cloudy today, FYI.

You need to add CYA which can take a few days to dissolve, you need to add chlorine to 12 -15 ppm because of the cloudy water. You probably have the start of an algae bloom because there is NO chlorine in your pool. You need to maintain the FC at 3 to5 ppm at all times. This will probably mean daily additions of liquid chlorine, which is my preferred form of chlorine since it has the least side effects. It is basically pH neutral (alkaline on addition and acidic on consumption) and does not raise CYA like dichlor or trichlor (which are net acidic), nor raise calcium hardness like calcium hypochlorite.

TA is good at 80 ppm, do not raise this. 50 to 70 is a better range for liquid chlorine or calcium hypochlorite and will give better pH stability.

CYA should be 30 to 50 ppm and when it is you should maintain the FC at 3 to 5 ppm (slightly higher is fine). Shock when there is OVER .5 ppm CC (Ideally CC should be 0 but .5 ppm is accpetable). Shock level is 15 ppm. You can enter the water once FC is below 10 ppm. How often you need to shock depends on usage.

Test chlorine daily at first. Strips are OK for this as long as they agree with the results from the Taylor kit but tst with the Taylor at least once a week. Once you learn your normal chlorine usage you might need yo only test it a few times a week. Use the Taylor test to determine CC weekly or whenever the water looks off (cloudy or green).

Test pH weekly. Keep it between 7.6 and 7.8. If it goes above 7.add acid and lower it to 7.6.

https://www.poolspaforum.com/forum/index.php?/topic/52523-some-truths-about-ph-and-ta/

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

Test TA and CH every 2 to 4 weeks. Test CYA monthly.

21 hours ago, Wolf5 said:

Sounds like I need to:

1. Raise the PH to 7.6.
2. Raise the CYA to 30-50 to stabilize the chlorine I add (currently just have liquid chlorine, not di or tri-chlor).

IF it's not below 7.0 it will rise on it's own. If it's below 7.0 add borax (the 20 mule team stuff in the laundry aisle) to raise the pH without affecting TA. pH increaser is sodium carbonate which will not only raise pH but will cause a big increase in TA, which you do not want. It is useful if using trichlor, which is very acidic. Not so much when using liquid chlorine or bleach. 2 oz. borax by weight will raise pH approx. .1 in 2000 gallons.Safest way is to add half the amount needed, wait about an hour with pump running, and test pH. Repeat as needed until you reach target pH. Slightly under is better than over target pH.

As I said before, Liquid chlorine (or plain, unscented laundry bleach) is my preferred chlorine source since it has the least side effects.

21 hours ago, Wolf5 said:

• How much liquid chlorine to add and how often?
• Stick with liquid or change to di or tri-chlor that has the stabilizer in it?
• With our UV filter, what level of chlorine should we stay at during the week? FC or TC, unsure which I'm asking about.

In 2000 gallons 1/4 cup 10% liquid pool chlorine will raise FC by about 1.5 ppm, 1/4 cup 6% Liquid chlorine laundry bleach (plain, unscented, unthickened)  will raise FC by 1 ppm. Store brand bleach is better than the well known national brand since it does not contain some of the additives for cleaner laundry. They won't hurt anything in your pool and are, in fact, found in some pool water clarifiers, but there is really not need to pay extra for them since we are only interested in the sodium hypochlorite.

Once again. sodium hypochlorite, whether pool chlorine or laundry bleach, has the fewest side effects and in reality, only adds salt to the water. Salt has no negative effect on water chemistry. Using a stabilized chlorine product will lead to an overstabilized pool which would require running higher FC levels for the same level of sanitation and higher FC for shocking. The only way to lower CYA is by draining and refilling with new water. If you have a cartridge filter or a non backwash DE filter this will happen faster then if you have a sand or backwashing DE filter and you regularly backwash.

As far as your UV unit goes:

US is NOT residual and only sanitizes the water in contact with the UV light. This means most of the water in the pool is NOT sanitized when foreign matter enters the pool. A FAST ACTING RESIDUSAL santizer (The only 3 EPA approved ones are chlorine, bromine, and biguinide/peroxide and the only one that is least problematic in a swim spa or swimming pool is chlorine). Every bather adds feces, sweat, and urine to the water no matter how clean they think they are, even if they shower before entering the water. Enteric water borne illnesses are a real thing and since UV has no resudial these pathogens won't be killed until they enter the UV reaction chamber. YOU STILL NEED TO MAINTAIN 3. to 5 ppm FC for a CYA of 30 to 50 ppm!

UV lights lose strength over time so unless you are changing the bulb on a regular basis (often every 6 to 12 months, depending on the unit you have) your water is not being sanitized in the chamber. This can get expensive.

UV light is NOT an oxidizer. An oxidizer is needed to oxidize organics added by bathers and organic matter such as pollen and leaves that might get into the water. Chlorine IS an oxidizer besides being an EPA approved sanitizer.

FC (free chlorine)  is the chlorine that sanitizes and oxidizes annd does not have a strong chlorine smell

CC (combined chlorine) is chlorine that has combined with ammonia and other organics, does not sanitize, smells like chlorine, and irritates the eyes and lungs. Only FAS-DPD testing will directly test CC. All other testing methods test TC

TC (total chlorine) is the sum of the FC and CC. All testing methods except FAS-DPD can only test total chlorine and CC has to be calculated by subtracting the FC reading from the TC reading. It's not hard but it is an extra step.

FC is what you want to maintain. CC should ideally be 0 ppm but up to .5 ppm is acceptable. If it is above .5 ppm it means you need to shock (raise FC to shock level, which depends on your CYA level).

[Wolf5]

Okay, this is a lot to take in, thank you very very much.

I'll add CYA and liquid chlorine to get the algae bloom removed. I've purchased the appropriate Taylor kit, will arrive next week (none at the nearby stores). Till then, I'll make due with strips and poolcalculator.com. 

I'll let you know how we turn out!

[Wolf5]

Hi again, tonight, I added 8 oz by weight of CYA granules to raise it to 30ppm. I know that the CYA will take days to set in.

I added 30 fl oz of liquid chlorine to raise the FC to 12ppm.

I ran the jets for about 10 mins to circulate, it auto shut off (expected), I ran them again for 10 mins, auto shut off, ran them again.

About 15 mins after I added the chlorine, I used a strip to test just to see what was going on. TC was 3 and FC was 1. Then, I tested again about 30 mins after that, and TC was 1 and FC was .5.

So, to me, this means that the jets are circulating through the UV filter, right? Why else would it drop so quickly after adding so much chlorine?

My immediate concern here is the potential algae bloom. How will it die out if my chlorine keeps dissipating? 

Trying to understand here, thanks for helping me out.

[waterbear]

You said the water was cloudy and you have a high CC. You need to keep shocking until the CC is 0 and the FC is holding. This is normal when you have something growing in the water. I don't think your UV is destroying that much of your chlorine. It seems more like the start of an algae bloom from no chlorine. Maintain the FC at 12 ppm until the water is clear, CC is 0, anfcthexFC is holding overnight 

 

[waterbear]

6 hours ago, Wolf5 said:

Why else would it drop so quickly after adding so much chlorine?

Simple, algae.

[waterbear]

sent you a pm

[Wolf5]

I just tested with my new Taylor kit. 

• FC =7
• CC = 1
• PH = 7.6
• TA = 110
• CYA = 35
• CH = 60

Looks like I need to:

• add liquid chlorine to lower the CC - how much to add? Just till CC is zero?
• lower the TA to 70-80 (how do I do this? PH decreaser?)
• increase CH?? Unsure how

thank so much. I’m getting there!

[waterbear]

On 12/11/2024 at 4:55 PM, Wolf5 said:

add liquid chlorine to lower the CC - how much to add? Just till CC is zero?

raise to shock level of 12 to 15 ppm, Keep it there until CC is less than .5 ppm (ideally 0 ppm). Let the spa circulate uncovered for a few hours (overnight is better) before retesting.

 

On 12/11/2024 at 4:55 PM, Wolf5 said:

lower the TA to 70-80 (how do I do this? PH decreaser?)

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

 

On 12/11/2024 at 4:55 PM, Wolf5 said:

increase CH?? Unsure how

buy some calcium hardness increaser at the pool supply, home depot, walmart, lowes, grocery stores that sell pool chemicals, or online and bring your CH to 130 to 150 (up to 200 ppm is fine). Calcium hardness increaser is calciutm chloride. Doesn't matter if it is anhydrous or dihydrate forms. Only difference is the amount needed for the same increase in calcium hardness so follow the dosing for the product you get.