Getting chemicals just right

[XsAllOverIt]

I've been playing around each day with my new Lamotte ColorQ tester and trying to get all the chemicals right. I went from the following on 12/28
FC 0.11, TC 0.11, pH 8.1, TA 86, CH 257, CYA 40
I've been struggling on getting that pH down and I added a little too much muriatic acid after those test results and put a chlorine puck in the hot tub for the night. To my suprise, I wound up with these results 24 hours later:
FC 5.92, TC 5.92, pH 6.6, TA 15, CH 309, CYA Didn't measure

Is that mostly from the puck? I'm heading to the store tonight to get some bleach and stopping the puck insertion idea due to what I believe to be the cause of most of the variance here. Am I correct on that?

 

[257WbyMag]

Probably a combination of the tablet and going a little overboard on the MA. You can aerate to raise the pH and you might also consider the addition of a little borax as well. The pH needs to be between 7.2 and 7.8.

 

[XsAllOverIt]

The hot tub is being aerated full-time. It's hooked up to the pool pump and heater and I run the pump full-time for 2 reasons - keeping the temperature at 70 degrees for a quick heat-up time for use and temperatures in the 20's for the past month. When they winterized the pool, they shut off all the lines to the pool and only those lines going into the hot tub are running with water. I'm not convinced this is the best scenario, but I relied on the pool company to know what they were doing. Can't slow the water circulation down. It was certainly a learn as you go process for me and after much research, I would have certainly did it differently with perhaps two pumps in the scenario. I also just got our hot tub cover right before Xmas, so that was the first time we had the opportunity to start using the hot tub. They were very slow on getting everyting up and running for us, but everything is working great now and we're enjoying our first winter season in the hot tub.

 

[zea3]

Hi, and welcome to TFP! Just for clarification, did you not test the CYA again or did the test show 0 CYA? Also, what type of tablets are you using? Are they calcium hypochlorite?

 

[XsAllOverIt]

I was simply LAZY last night. I've been testing the CYA each day along with everything else, and it's been a steady number between 30-40 in the last week. I'm not sure about the tablets. They are 3" pucks - Chlorine, but will check on them. I plan on putting bleach in from now on when CH goes down and leave them for when I go away for a length of time and the pool is up and running. All I read, I know I can't manage the small hot tub with a big puck obviously after testing in the past 2 weeks with FC jumping from HIGH down to LO and back to 5.92 yesterday. It just dissolves too quickly with a lot of water movement.

 

[zea3]

The CH will only go down with water replacement. 309 is managable so I wouldn't do anything to it at this point, just make sure the tablets you are using are not Calcium Hypochlorite. Look at the active ingredient on the lable and it should tell what type of chlorine you are using. Cal-hypo tablets will raise CH over time, and trichlor and dichlore will raise CYA. You want to use any form of dry/solid chlorine sparingly to avoid long term issues with high CH and CYA. Read through pool school in the upper right corner and familiarize yourself with the pool calculator. The pool calculator has a section near the bottom that calculates the effects of adding specific chemicals to the pool. That is very helpful for learning how your pool reacts when chemicals are added.

Not to be a test kit snob, but we usually don't recommend the Lamotte kit. You can do a google search at the bottom of this page for "Lamotte color q" to read about issues that may come up using the Color Q kit. That way you can be aware of the kits limitations and recognize when errors are likely to occur.

 

[susa]

> Look at the active ingredient on the lable and it should tell what type of chlorine you are using. Cal-hypo tablets will raise CH over time, and trichlor and dichlore will raise CYA.

Are TriChloro-S-Triazinetrione of type trichlor ? (Leslie's Pool Supplies store brand product).

 

[XsAllOverIt]

CH can go down easily with the next backwash of the filter, so I'll keep an eye on that.
If I use bleach from now on, will CYA and CH remain constant?

Yeah, I've been testing with my LaMotte and taking a water sample to the store to determine differences. I read the posts on the LaMotte and it appeared most of the problems were with cYA. The pH, and tA seem to be dead on. CH and CYA have been off a little, but I wasn't too comfortable with the last readings I got from the store either. I'm getting another water test today and will test tonight myself to compare. I've never had too much luck comparing with the eye when we had a portable hot tub and a test kit. I know the most important readings are pH and tA, so that's a good thing.

 

[257WbyMag]

Since bleach has no CYA, it will not increase the CYA. CYA can decrease over time with water change outs. Bleach will not affect the CH either but what will affect the CH is the fill water. Some fill water is pretty hard and that will raise the CH over time.

 

[zea3]

> Look at the active ingredient on the lable and it should tell what type of chlorine you are using. Cal-hypo tablets will raise CH over time, and trichlor and dichlore will raise CYA.

Are TriChloro-S-Triazinetrione of type trichlor ? (Leslie's Pool Supplies store brand product).

Yes that is trichlor. It will contain CYA, also known as stabilizer or conditioner. Most dry/solid chlorine sold in chain pool stores will have either trichlor/dichlor or cal-hypo. There are dry chlorines that contain lithium that do not raise CYA or CH, but they are expensive and tend not to be stocked in chain stores.

Check [/url=http://www.poolcalculator.com] the pool calculator, [/url] near the bottom will be a section for "results of adding chemicals" that you can use to calculate how much your trichlor is raising your CYA.

 

[chem geek]

Note that aeration will not raise the pH very quickly when the TA is as low as yours was. The Trichlor pucks/tabs should not be used in a spa since they dissolve too fast and have the pH and TA drop too quickly as a result. For a spa, you can use the Dichlor-then-bleach method though you already have CYA in the water at this point and can start using bleach (i.e. no need for Dichlor). You will want to keep your TA low, probably around 50 ppm, and should add 50 ppm Borates (from boric acid such as in Proteam Gentle Spa or direct sources as listed in Recommended Pool Chemicals.

As for the side effects from chemicals, the following facts are independent of concentration of product or of pool/spa size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

 

[XsAllOverIt]

Thanks. Will post on the weekend on how it's going...

 

[JesseJames]

The CH will only go down with water replacement. 309 is managable so I wouldn't do anything to it at this point, just make sure the tablets you are using are not Calcium Hypochlorite. Look at the active ingredient on the lable and it should tell what type of chlorine you are using. Cal-hypo tablets will raise CH over time, and trichlor and dichlore will raise CYA. You want to use any form of dry/solid chlorine sparingly to avoid long term issues with high CH and CYA. Read through pool school in the upper right corner and familiarize yourself with the pool calculator. The pool calculator has a section near the bottom that calculates the effects of adding specific chemicals to the pool. That is very helpful for learning how your pool reacts when chemicals are added.

Not to be a test kit snob, but we usually don't recommend the Lamotte kit. You can do a google search at the bottom of this page for "Lamotte color q" to read about issues that may come up using the Color Q kit. That way you can be aware of the kits limitations and recognize when errors are likely to occur.

I took your advice and googled the Lamotte Kit and found a 2007 TFP thread. Just curious if the accuracy issues with CH and CYA still exist or has Lamotte improved the tests over the last three years?

 

[zea3]

The CH will only go down with water replacement. 309 is managable so I wouldn't do anything to it at this point, just make sure the tablets you are using are not Calcium Hypochlorite. Look at the active ingredient on the lable and it should tell what type of chlorine you are using. Cal-hypo tablets will raise CH over time, and trichlor and dichlore will raise CYA. You want to use any form of dry/solid chlorine sparingly to avoid long term issues with high CH and CYA. Read through pool school in the upper right corner and familiarize yourself with the pool calculator. The pool calculator has a section near the bottom that calculates the effects of adding specific chemicals to the pool. That is very helpful for learning how your pool reacts when chemicals are added.

Not to be a test kit snob, but we usually don't recommend the Lamotte kit. You can do a google search at the bottom of this page for "Lamotte color q" to read about issues that may come up using the Color Q kit. That way you can be aware of the kits limitations and recognize when errors are likely to occur.

I took your advice and googled the Lamotte Kit and found a 2007 TFP thread. Just curious if the accuracy issues with CH and CYA still exist or has Lamotte improved the tests over the last three years?

I haven't heard of any updates. There are a few members that use that kit, maybe they can chime in?

 

[XsAllOverIt]

I just took my water to be tested today and it matched VERY well on all of the items including CH and CYA as an FYI. I go to to a pool store once a week to confirm. The last week, it was varied from their results with CH and CYA. I'll post what I find next week.

 

[XsAllOverIt]

OK, another question. I'm now adding bleach instead of using pucks. Generally, it's kept at 70 degrees unless it's being used (twice a week, 2-4 people each time), how often should I expect to add bleach for a 620 gallon gunnite/plaster hot tub? I've got my numbers all within range. I've also got the pump running full-time resulting in a lot of bubbling since the pump is for both the pool and spa and the pool is winterized.

 

[chem geek]

OK, another question. I'm now adding bleach instead of using pucks. Generally, it's kept at 70 degrees unless it's being used (twice a week, 2-4 people each time), how often should I expect to add bleach for a 620 gallon gunnite/plaster hot tub? I've got my numbers all within range. I've also got the pump running full-time resulting in a lot of bubbling since the pump is for both the pool and spa and the pool is winterized.

Without an ozonator, the rough rule-of-thumb that is independent of spa size is that every person-hour of soaking in a hot (104ºF) tub needs around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS). You didn't say how long the people are soaking, but if it's 2 people for a half-hour, then that would be around 5 fluid ounces of bleach needed, but 4 people for an hour would be closer to 20 fluid ounces of bleach.

Just start out adding amounts based on the formula and then measure the FC level before the next soak. You want to add enough chlorine after a soak so that you still have at least 1-2 ppm FC before you next soak. You can then adjust your dosing accordingly.

 

[XsAllOverIt]

Thanks. So FC shouldn't change unless we use it normally?

 

[chem geek]

When you aren't using the tub at all, then the FC will still drop some. At usual temperatures that people have for the tub between uses, the FC drops around 25% per day. So 4 ppm FC will become 3 ppm FC and 2 ppm FC will become 1.5 ppm FC, etc. So there is some drop which is why one needs to regularly add chlorine even when not using the tub, though they may be able to add it every other day or so (but not just once a week -- that won't be enough).