Help a BBB newbie with some questions

[Garet Jax]

Hello all,

I have just refilled my hot tub with ~300 gallons of fresh water. I am using the TF 100 Kit and got the following measurements:

CH 70 ppm
pH 7.5 ppm
TA 70 ppm

After making these measurements, I added Alkanlinity increaser and calcium hardness increaser to raise TA by 10ppm and CH by 70ppm. I have not remeasured the pieces above after making the adjustments.

I then measured:
FC 0.5ppm
CC 0.5ppm
CYA 0

I wanted to make sure that getting a CYA of 0 was reasonable.

In following http://www.troublefreepool.com/how-do-i-use-chlorine-in-my-spa-or-pool-t10095.html, I want to get my Chlorine levels to ~35ppm and raise my CYA to ~30ppm.

I am using the following product:
http://www.spa-essentials.com/mp/v/...110VgnVCM10000053d7010aRCRD&vgnextfmt=default

I am assuming it will raise chlorine and CYA levels since it appears to be 99% dichloro. I have put in roughly 1.5 tablespoons and according to the directions, this should raise the chlorine levels by ~20ppm.

Do I seem to be on the right track or am I missing things terribly? Thanks.

 

[Garet Jax]

OK - I just retested the CH levels and got up to 40 drops and still didn't get blue. All I had was clear. According to the back of the product I used, the ppm should have only increased by 60-80ppm. So I originally measured it at 60-70ppm, but now measured it at > 400ppm.

For a hot tub, it this a problem? Do I flush the water and start again?

 

[Garet Jax]

I may also have over-chlorinated it. Using the TF-100 kit, the chlorine test was far redder than the pH test after I added the chrlonating concentrate.

 

[Garet Jax]

Well I am trying to flush the hot tub to get the levels of Chlorine and CH back down to manageable levels. This is definitely a work in progress.

 

[chem geek]

OK - I just retested the CH levels and got up to 40 drops and still didn't get blue. All I had was clear.

The CH test shouldn't look clear. It goes from a purple to a blue. If you didn't start out with purple, then something was wrong with the test. Are you sure you added the reagents in the proper order with the calcium buffer first and then the calcium indicator dye? After you added the dye, the water should have turned purple.

 

[Garet Jax]

[quote="Garet Jax":13yaog4z]OK - I just retested the CH levels and got up to 40 drops and still didn't get blue. All I had was clear.

The CH test shouldn't look clear. It goes from a purple to a blue. If you didn't start out with purple, then something was wrong with the test. Are you sure you added the reagents in the proper order with the calcium buffer first and then the calcium indicator dye? After you added the dye, the water should have turned purple.[/quote:13yaog4z]

Of course you're right. Not sure what I was doing...

I just took an updated set of measurements:

CH - 80ppm
TA - 80ppm
pH - 7.5ppm
FC - 6ppm
CC - .5ppm
TC - 6.5ppm
CYA - 0

I am going to try and raise the CH to ~140ppm.

I am a little confused since I definitely raised the chlorine too high. I was off the charts and needed to drain water and replace it to bring it down. I drained and replaced a lot, but am still at the high end of the spectrum (6ppm for FC). But through it all my CYA stayed at zero.

What should my CYA level be? Is 0 OK or should it really be 20-30? What product should I be using to chlorinate the hot tub and also raise CYA?

 

[Garet Jax]

Well my CH has climbed to 120. Added a little more chemical to get it to 140 or so. Will leave it for the night.

After more reading, it appears the Chlorine chemical I am using does not appear to be Dichlor since the CYA remained at 0 throughout my roller coaster chlorine ride. The main ingredient is "Sodium dichloro-s-triazinetrione dihydrate" and is 99% of the ingredient of my bottle. The other 1% is not specified.

What Dichlor product do you guys use and where do you buy it?

Thanks.

 

[Garet Jax]

Well my CH has climbed to 120. Added a little more chemical to get it to 140 or so. Will leave it for the night.

After more reading, it appears the Chlorine chemical I am using does not appear to be Dichlor since the CYA remained at 0 throughout my roller coaster chlorine ride. The main ingredient is "Sodium dichloro-s-triazinetrione dihydrate" and is 99% of the ingredient of my bottle. The other 1% is not specified.

What Dichlor product do you guys use and where do you buy it?

Thanks.

Well after doing even more reading, it appears that I am using very good Dichlor at 99%. So it either means that I suck at measuring CYA (very possible) or I am using some stuff that is old and weak (possible even though I just bought it today) or something else.

 

[chem geek]

If you added 20 ppm FC worth of Dichlor, then your CYA would be around 18 ppm, but the CYA test is sometimes hard to read. Did the mixture of CYA reagent with spa water get cloudy at all? So when you filled to the top of the tube it was clear or was it just not cloudy enough to obscure the black dot? I'd just keep using the Dichlor for another 10-20 ppm FC before you switch to bleach. Don't overthink this or worry too much about it. You're doing fine.

 

[jblizzle]

Everything below 20ppm CYA may show as 0ppm. You can not test the actual CYA level really until the CYA is up closer to 30ppm. You are supposed to be keeping track of how much dichlor you are using so you can use the poolcalculator to calculate how much CYA you have added.

Once the CYA is at the proper range, then you have to switch to liquid chlorine.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[Garet Jax]

Everything below 20ppm CYA may show as 0ppm. You can not test the actual CYA level really until the CYA is up closer to 30ppm. You are supposed to be keeping track of how much dichlor you are using so you can use the poolcalculator to calculate how much CYA you have added.

Once the CYA is at the proper range, then you have to switch to liquid chlorine.

Posted from my Droid with Tapatalk ... sorry if my response is short

Now that makes sense. When I over chlorinated I was thinking that I was going to add enough Dichlor to get CYA up to 30ppm right away. It wasn't until I looked at the Taylor Chlorine tester and saw that it maxed out at 5ppm that I realized I had put too much in.

It left me confused since I couldn't understand why a document on here was instructing me to get CYA to 30ppm while the FC shouldn't really go above 5ppm. It never occured to me that these measurements were over a period of time. Thanks for connecting the dots.

 

[Garet Jax]

If you added 20 ppm FC worth of Dichlor, then your CYA would be around 18 ppm, but the CYA test is sometimes hard to read. Did the mixture of CYA reagent with spa water get cloudy at all? So when you filled to the top of the tube it was clear or was it just not cloudy enough to obscure the black dot? I'd just keep using the Dichlor for another 10-20 ppm FC before you switch to bleach. Don't overthink this or worry too much about it. You're doing fine.

I spent quite a bit of time reading about the CYA test last night and realized that I wasn't doing it completely as instructed. With that said, I was able to get 100% of the mixed liquid into the test tube and still see the black dot very easily so my guess is that CYA is stil quite low in my hot tub. Unfortunately, I didn't track how much Dichlor I put in yesterday (especially since I drained water and replaced it) so I really don't know what the CYA reading should be. I will continue to use the Dichlor and test CYA until I get it to 20-30ppm.

Thanks for your help and encouragement. When you are doing something for the first time, it is very easy to not be confident that you are doing the right thing. Simple nudges or encouragement go a long way to instilling that confidence - so thanks.

 

[jblizzle]

5ppm is not an upper limit for the chlorine. You should be using the FAS-DPD chlorine test in the TF100 to get true readings of the chlorine level.

The appropriate FC levels depend on the CYA level. Review the chart and information in Pool School.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[Garet Jax]

5ppm is not an upper limit for the chlorine. You should be using the FAS-DPD chlorine test in the TF100 to get true readings of the chlorine level.

The appropriate FC levels depend on the CYA level. Review the chart and information in Pool School.

Posted from my Droid with Tapatalk ... sorry if my response is short

I have been looking at that chart, but have had trouble coming up with recommendations since my CYA level is so low. Based on the sticky at the top of the Spas and Hot tubs section, I am aiming for a CYA of 30ppm. According to the chart, my FC should be around 4 with a minimum of 2 and a shock of 12.

I have also been using the FAS-DPD chroline test from the TF100 kit. After replacing the water last night, my FC was 6ppm and my CC was .5ppm.

I took another measurement over lunch and my FC dropped to 2.5ppm. My CC was still .5ppm.

I added a little more Dichlor, but was surprised how much the FC dropped in ~14 hours. Everything I read suggested 25% per day so I was expecting 1-2ppm, not 3.5ppm.

Now given that I have so little stabilizer, I guess FC dropping so much so quickly is OK.

Thoughts?

 

[jblizzle]

Is it covered? If not, the sun will break down a lot of the FC since your CYA is still so low.

 

[chem geek]

You don't go by the chlorine/CYA chart, per se. For spas, you normally want to start your soak with 1-2 ppm FC so that you don't smell much chlorine. You add a lot of chlorine after your soak and the FC goes quite high because it has to be enough to handle the bather waste. It will usually be above 2 ppm most of the time. You don't generally get algae in spas because of the very hot water and having it covered so no light, so between that and the higher FC that comes after you dose after a soak, you don't have to follow the chlorine/CYA chart minimum. You can if you want to, but you don't have to. You DO want to make sure you ALWAYS have chlorine in the spa, so don't let it get too low and the easiest way to make sure is to test your FC just before your soak and see that it's at least 1 ppm FC and probably 2 ppm FC to be on the safe side.

If the spa is not covered, then you'll need to add more chlorine to make up for the loss from sunlight that is in addition to the bather load. You'll lose more than half the FC to sunlight at a CYA of 30 ppm. Usually, though, spas are covered.

 

[Garet Jax]

Is it covered? If not, the sun will break down a lot of the FC since your CYA is still so low.

Yes it is covered.

 

[Garet Jax]

OK - I am learning a little more how to use the Dichlor. My FC is falling ~3.5 ppm overnight and my CC has risen from .5ppm 2 days ago to 1ppm today. I am thinking I need to shock the pool using http://www.troublefreepool.com/pool-school/shocking_your_pool. Given that I am talking about a hot tub, what do I need to change?

My CYA level is still unmeasurable so it is probably < 10 or even 0. Is it OK for me to use Dichlor to do the shock versus straight chlorine or bleach?

Since my CYA is still so low, the table doesn't apply to me so I am going to aim to keep the FCat 10ppm.

Do I still need to brush the hot tub the way I would a regular pool?

Any other things to consider. Given that this will be my first shock, are there any recommendations? Thanks.

 

[chem geek]

Spas have such a low volume and therefore a high bather load (when used) that the normal things like the overnight chlorine loss test and CC levels do not apply close to the times when you are using the spa. Here's what happens. After you use the spa, you add chlorine as soon as you get out to oxidize the bather waste. Such oxidation does not happen immediately so there will often be measurable CC and the FC you add will drop by quite a lot and this process takes hours. So you should not be measuring your CC after your soak nor should you test the FC and measure it's drop after your soak. If you want to do an overnight chlorine loss test, you have to wait a day or two not using the spa first (still maintaining the FC level prior to this to ensure you do oxidize any remaining bather waste).

Also, if you are in the first days after a fresh refill and haven't used enough Dichlor to build up measurable CYA, then the chlorine loss will be higher from chlorine outgassing since the active chlorine level will be higher. So again, wait a week or so when you switch to using bleach before doing overnight chlorine loss measurements (again, after not using the spa for a day or two).

Do you have an ozonator? If you have an ozonator, then when you aren't using the spa it will react with chlorine creating a greater chlorine demand. Also realize that with the hot spa temperatures, even after the CYA builds up to 30-40 ppm the "normal" 24-hour FC loss with no bather load is around a 25% drop. With an ozonator, it can be 50% or more.

If you want to shock with Dichlor at this point, you can do that. I'd raise the FC to 10 ppm or perhaps 15 ppm. The added CYA should help slow down chlorine outgassing.

If you do find high chlorine demand when CYA is present and with no ozonator and no bather load, then you should decontaminate your spa. If you never decontaminated, you may have biofilms in the piping or filter. Decontamination usually involves using Spa System Flush followed by superchlorination.

If the spa is plaster, then you brush it, but if it's acrylic/fiberglass (i.e. a typical standalone spa), then you just wipe the area just above the waterline (with a cloth, not a brush) since that typically gets some biofilm since it's moist from evaporated water but doesn't get disinfected by the chlorine.

 

[Garet Jax]

OK - it looks like I have my numbers under control:

CYA >20ppm and < 30ppm
CH 150ppm
TA 70ppm
FC 4.5ppm
CC 0.5ppm
pH ~7.6

Here is what I understand about the numbers over time:

CYA will stay the same unless I add it. So now that I have CYA where I want it, I should switch to bleach and stop using Dichlor.
CH will stay the same unless I try to adjust it.
pH may rise or lower and I need to measure it daily to keep it around 7.6.
FC will fluctuate the most and should be between 2 on the low side and 5 or 6 on the high side unless I am shocking. I will need to test and adjust possibly daily.
CC should remain at .5ppm or lower. If it goes higher it means the chlorine is actively killing off bacteria and I may need to shock it.
TA I know very little about this number long term - any advice?

Thanks for all your help folks.