Chlorine Levels

[Daveshottub]

I cant maintain chlorine levels in my tub, no matter how much chlorine I add the free chlorine level doesn't seem to change. Tested my test strips in a glass of hot tub water and added some chlorine granules and strip showed the chlorine in there with no problem. Have now added loads of chlorine but no change, free chlorine still showing as zero!

Tub recently restarted after several weeks, dosed with non chlorine shock and chlorine, ph and alkilinity levels showing as ok

 

[Bama Rambler]

Welcome to TFP.

Did you drain and refill the tub? Did you decontaminate it when you restarted it?

Telling us you added loads of chlorine doesn't really tell us anything. How much and what type have you used?

 

[Daveshottub]

Welcome to TFP.

Did you drain and refill the tub? Did you decontaminate it when you restarted it?

Telling us you added loads of chlorine doesn't really tell us anything. How much and what type have you used?

I have added around 100g of FiClor chlorine granules and 40g of Fi Clor non chlorine shock, tub is approx 1000litres. I didn't drain and refill.

 

[Bama Rambler]

Chem Geek is our resident spa expert, maybe he'll chime in.

 

[scott.MI]

what exactly do you mean restarted after several weeks?

If its been sitting for several weeks either empty with water in the pipes, or full of water and not treated/circulated even a little bit...sounds like you definatly have to decontaminate. I recently read it does not take very long for biofilms to start in the pipe when not chlorinated.

 

[linen]

Do you have a drop based OTO Total Chlorine test...it is usually attached to same block as a ph test...looks something like the the thing in the middle of this with the yellow and red caps:

If you do, test with that and post what you get.

 

[chem geek]

I think a decontamination is in order (SeaKlear Spa System Flush) and you should get a proper test kit (TFTestkits TF-100 or Taylor K-2006). See Using Chlorine in a Spa, but after you decontaminate I would target a TA of 50 ppm and definitely use 50 ppm Borates.

 

[Daveshottub]

Thanks Chemgeek, sorry to be thick but I dont understand the second part of your message:

I would target a TA of 50 ppm and definitely use 50 ppm Borates.

Also where can I acquire the stuff?

 

[chem geek]

Be sure to get the proper test kit. Then do the decontamination procedure. After all that, you can move to balancing your fresh fill water. Your Total Alkalinity (TA) will probably be higher than 50 ppm from your fill water so to lower it you follow the procedure in Lower Total Alkalinity. For the 50 ppm Borates, the easiest method is to add boric acid which you can get as described in the Borate section at the bottom of Recommended Pool Chemicals.

 

[Daveshottub]

Think I've diagnosed the problem! After adding another 40g of chlorine granules and seeing no change in FC level, I've added 40ml of bleach and bingo, now got a healthy chlorine level! I suspect my chlorine granules are goosed, they are from last year and are clumped together from moisture so suspect they've reacted with the moisture and lost most of the chlorine, I'll monitor chemistry for a couple of days before using! Chlorine TABLETs on order!

 

[chem geek]

I'm glad you figured out what was going on. That's a lot easier to handle that having to go through the full decontamination with a water change. Usually solid chlorine doesn't go bad that quickly, but it sounds like it got moisture in it and in that case it will break down.