new 20,000 gal salt water pool won't maintain any chlorine

[citznfish]

Hello,

I am new to the forum and new to salt water pools. We have a new pool that has been completed for about 2 months now. I am having issues with it maintaining any chlorine levels and I am looking for advice on what to try next.

Here is what I have been doing, and my equipment.

Hayward Omnilogic system with a Hayward T-Cell 15

Initially I had this set to 50% chlorinating and the chlorine levels were always .20 or maybe even 0. PH was high at 7.8 or 8 and Alkalinity was at 100ppm. Salt was at 2900ppm. I have been adding liquid chlorine to try and bring the levels up but it is only temporarily, and adding acid to bring the ph down. I added one more bag of salt to bring total salt to 3100-3200ppm

10 days ago I bumped the generator up to 75% and we went on vacation. I came back last night and just tested the water. Chlorine was still at 0. PH was high again at 7.8 or 8.0 and alkalinity was still in the good range at 110ppm. Instant salt shows 2892 and average salt at 3215ppm.

I am going to go buy more liquid chlorine and add it in, but something seems to be amiss in my opinion if I cannot get any chlorine to generate. The equipment deinitely shows that it is generating chlorine though.

I have now bumped the generator up to 100%. I do not know if this is normal for a 20,000 gal pool.





Any advice would be appreciated!

Thank you,
CF

 

[Texas Splash]

CF, we should be able to help you. It would first be very helpful to know what all of your test readings are.... especially your CYA. Can you post all of them please with your TF-100 or Taylor K-2006? We can advise from there.

 

[Divin Dave]

Questions.
1. What is your CYA level? CYA protects the chlorine from being burned off by UV from the sun. If you dont have any CYA, or its very low or inadequate for your location, then your FC will not last very long at all. Only 2 things destroy FC, Algae and UV. So, one or the other is the culprit.

2. Do you have any visible algae? Adding chlorine will attack the algae and in doing so, the FC will be destroyed by attacking it.

3. Do you have any errors on your auto system at all? Such as a low flow, inspect cell, chlorine not generating? Anything out of the ordinary?

4. Why did you fill out your sig the way you did? I will give you a ha ha, to apease your sense of humor. People who are trying to help you rely many many times on knowing what type of equipment you have in order to give you a good answer to any question you might have. The accuracy of the info in your sig makes a difference in the quality of the answers. And trust me, no one wants to continually ask you what equipment you have.

5. What is your location? - generally speaking is good enough. The reason why we might want to know that is because as mentioned above, UV will destroy chlorine.
If your location is the Arizona desert, the UV will be much higher than in pennsylvania mountains, and so recommendations on CYA levels take into account what the UV level might be were you are. If you will perhaps add the state where you are located, it would result in less questions for you to answer before an well thought out reply can be provided back to you.

6. What type of test kit are you using to test with?
7. Do you have any combined chloramines? (can only be tested with FAS-DPD test kit).

 

[citznfish]

Hello all,

Thanks for the replies. I only had a 5-in-1 kit that came with the pool. I went and had the water tested for CYA and it was at zero. I bought 8lbs and added 4 in this afternoon and will add the remaining 4 lbs later in the week. I am assuming that this is what was causing the chlorine to disappear so fast. There is no algae as far as I can tell, pool has only had water in it for two months

Divin Dave, to answer your specific questions,

1) The level was 0. I am in Southern California just north of Los Angeles so it does get a lot of sun and heat.

2) absolutely no visible algae. However it is a pebble pool so it might be a little tough to see.

3) no errors in the system at all.

4) I must have done that when I first registered years ago. I didn't even realize I had a signature, lol. I'll add the equipment.

5) Southern California, just north of Los Angeles and just east of Malibu

6) I have a 5-in1 that came from the pool builder. It does not do CYA nor Salinity.

 

[Texas Splash]

No CYA with a SWG system will make it next to impossible to maintain the required FC. Your cell just can't keep up with FC loss from the sun. It will also be tough to confirm your CYA without the proper test kit. The stores are notorious for horrible testing. I would definitely advise you to order a TF-100 as soon as you can. For your SWG pool, your CYA should be up around 70-80 to protect the FC. Until you can get that confirmed/resolved, you may be forced to supplement FC production with some regular bleach. It all begins with the proper testing.

 

[Divin Dave]

Thanks for filling out your signature. It really helps a lot.

0 CYA is your biggest problem right now and as Texas Splash says, likely is the root cause of low FC.
Its good, and you are lucky, that you have no visible algae - yet.


Recommend that you get a good test kit that includes a FAS-DPD chlorine test, and a CYA test.
EIther the tF100 or Taylor K2006C is what we recommend here at TFP. They both are very accurate and repeatable.
The TF100 contains more quantities of test regents a homeowner uses most, so in that respect, it is the best bang for the buck.
TFTestkits.net for teh TF100 and the Taylor 2006 kit is available lots of places online.

Based upon your pool volume of about 20K gallons, and a CYA target level of 70ppm, pool math tells me you need about 11.5 lbs of CYA.
Pool math and a good test kit will be your best investment you could possibly make for your pool. http://www.troublefreepool.com/calc.html

Here are a couple of references in case you havent found them in Pool School yet.
Pool School - Recommended Levels
Pool School - Chlorine / CYA Chart
Pool School - ABCs of Pool Water Chemistry

hope this helps...