Indoor salt water pool: 11,500 gallons

[LagoonLover]

I moved into this house a few months ago and this is the first time I have had to take care of a pool. I was having trouble getting the chlorine levels down and I believe it was because too much salt was added and the chlorine generator was turned up too high before we moved in. I was told to use thio-trine to get the cholrine levels to go down so I did. I may have used too much because now when I test the water, I report the chlorine levels to be zero. Also the last time I tested the water, the salt ppm was at 4.4 which was way up from a 3.7 ppm reading two days beforehand. The pool has been above 85 degrees F most of the time but usually closer to 95 F. The pH is maintaining about 7.5-8. I have also turned the chlorine generator all the way up and still zero chlorine.

Any thoughts on what I should do now are greatly appreciated.

 

[LagoonLover]

First time pool owner

I'm new here and would love to get some questions answered regarding my 11,500 gallon salt water pool. I think I used too much thio-trine to get the chlorine levels down and now I report zero chlorine levels on my water tests.



Mod note: I merged two threads to keep all of the info together. Kim

 

[jblizzle]

Re: First time pool owner

Welcome to TFP!

Why did you think you needed to lower the chlorine level?

 

[LagoonLover]

Re: First time pool owner

It was obvious just when walking into the pool house that the chlorine level was too high. It was even more obvious when swimming in it, even for a short time. The water test I do was also reporting the chlorine much higher than recommended.

 

[JoyfulNoise]

You need to be careful with adding chemicals like thiosulfate. The FC would have come down in its own just by shutting off the SWG. You're going to have to continue to add chlorine until you react away all of the thiosulfate. You should use liquid chlorine/bleach to do this as an SWG just can't output enough chlorine at a high enough rate. If you had any CCs in the water prior to adding the thiosulfate that is doubly bad because thiosulfate will react with chloramines to release ammonia. Ammonia causes a very strong chlorine demand.

So just keep adding bleach until the water starts to hold chlorine.

 

[MarianParoo]

Re: First time pool owner

That "obvious" indication was probably high combined chlorine (CC), not high free chlorine (FC). There is a huge difference. What "test" did you use? We only really recommend home testing with a FAS-DPD chlorine test found in one of these kits: Pool School - Test Kits Compared

 

[pooldv]

Re: First time pool owner

Welcome to TFP?

Do you have any CYA in the pool? aka cyanuric acid or stabilizer. If not, add about 30 ppm to your pool and it will buffer the harshness of the chlorine.

Have you had a look at the ABCs yet? Pool School - ABCs of Pool Water Chemistry

 

[LagoonLover]

I have no CYA in the pool. I will have to double check exactly what kind of water testing kit I have but it is exactly the same as the pool guy who came and walked me through how to do everything when I moved in here so I assume it is sufficient.

I have plenty of bleach in the pool house now. How much should I be adding at a time and should I just be adding it directly into the pool?

 

[JoyfulNoise]

I have no CYA in the pool. I will have to double check exactly what kind of water testing kit I have but it is exactly the same as the pool guy who came and walked me through how to do everything when I moved in here so I assume it is sufficient.

I have plenty of bleach in the pool house now. How much should I be adding at a time and should I just be adding it directly into the pool?

I didn't think you would have CYA as you live in the Netherlands and it is likely not allowed by European standards. It's an indoor pool anyway, so even if you did use CYA you would not want much more than 20ppm.

In the US, we use test kits provided by Taylor Technologies (you can look them up on the internet) that use the FAS-DPD titration method for measuring free chlorine and combined chlorine separately. Look it over and see if you can find a supplier where you are that provides a similar test methodology.

As for how much bleach to add, I would not add more than a few ppm at a time until it starts to hold. You can use PoolMath on this website to figure out the amounts of bleach needed. Essentially you have to neutralize all the thiosulfate that might be left in the water. It will take some experimenting to figure that out by adding bleach, waiting for it to mix (pour it in in front of the deep end water return) and then testing within 20-30mins to see if there's any FC holding in the water.

Good luck,
Matt

 

[LagoonLover]

I live in Nederland, Co not the Netherlands lol. I live at about 9000 feet so let me know if that matters at all. Im going to go add bleach and my test kit does test for combined chlorine and free chlorine separately. Thanks for the help everyone, I will report back tomorrow or tonight and tell you how its going.

 

[jblizzle]

Well, please update your location (City, State or City, Country) in your profile as described HERE as it will help us help you.

 

[JoyfulNoise]

I live in Nederland, Co not the Netherlands lol. I live at about 9000 feet so let me know if that matters at all. Im going to go add bleach and my test kit does test for combined chlorine and free chlorine separately. Thanks for the help everyone, I will report back tomorrow or tonight and tell you how its going.

HAHAHAHAHA!!!

I read that last night and obviously read it wrong

OK, so others have chimed in quite a bit with advice. Hopefully you have corrected the thiosulfate problem. I would suggest NOT using that anymore as there is really no reason to ever use a chemical method for FC reduction.

Since you have a indoor pool, you need to give us as much information as you can regarding what equipment you have and what the indoor space is like (ventilation, sky-lights, etc). Indoor pools have to be run quite a it differently than outdoor pool. BUT before we can help you, you must get a proper test kit. It is the only way we can accurately advise you. Order either a TF-100 from TFTestkits.net OR a Taylor K-2006 from Amazon.

 

[Isaac-1]

As the others have said you need to get some CYA in the water, it is not just about protecting from sunlight like many in the industry think, anything between 20 and 30 ppm is good, also get the TF-100 test kit, not the Taylor K-2006, for outdoor pools it does not matter which one you get, but for indoor pools the CYA testing tube that comes with the TF-100 reads down to 20 ppm, the one in the K-2006 only reads down to 30 ppm. (outdoor pools should maintain CYA at 40-70 ppm depending on climate and chlorine source).

20 ppm and 2.5 ppm FC is a good compromise target level once you get things back under control

Ike

p.s. most of the "chlorine smell" people think means chlorine is too high is really combined chlorine levels which is often caused by lack of free chlorine, however with an indoor pool you may need another supplemental oxidizer, either using an ozone system, or UV system, or chemically treated with MPS if you use MPS it can cause false CC readings on the common FAS-DPD chlorine test, however Taylor does make a special MPS elimination test that you can use, or you can just assume your CC readings are falsely high for 3-5 days after adding MPS.

 

[LagoonLover]

My test kit is a Taylor K-2105. Thanks for all the help everyone. I tested my pool this morning and the chlorine level is basically back to normal. I will keep adjusting as necessary and I will get as much info about my setup as possible to you guys for next time I have a question. Thanks again!!

 

[jblizzle]

I think you need a test kit upgrade I think you need a test upgrade

 

[JoyfulNoise]

My test kit is a Taylor K-2105. Thanks for all the help everyone. I tested my pool this morning and the chlorine level is basically back to normal. I will keep adjusting as necessary and I will get as much info about my setup as possible to you guys for next time I have a question. Thanks again!!

The 2105 uses the DPD only indicator and is a color comparator type test. It's ok for quick spot checking but it can not give you fine resolution.

The K-2006 uses the DPD-FAS test which is a pink-to-clear endpoint titration method. In that test you count drops until you get to clear endpoint and then multiply the drop count by a conversion factor (like the TA test). It is A LOT more accurate than color comparison.