Yesterday we tested our spa FC to be 25! Strange thing is we had not added any chlorine to the spa to cause this rise. Today we retested the water after leaving the lid open all night and found the FC to be above 30 by then I had just stopped adding drops.No chlorine had been added? I just dont know what is going on to cause this. Any ideas? Im thinking of draining and starting over but sure would like to understand what is going on here.
Spa free chlorine suddenly rising very high
- Thread starter fishcrazy
- Start date
- Jul 3, 2013
- 9,028
- Pool Size
- 15000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-40
there is no way chlorine is rising on its own, something is in it adding to it... do you have a frog system or something like it? are there pucks in it your not seeing?
I was reluctant to even post this because I know that what you say is true. I just don't get it. I want to test it again and find out I just did something brain dead like I sometimes can do. I do not have any sources of chlorine that feed the spa. I simply add some after each use as needed.
- Jul 3, 2013
- 9,028
- Pool Size
- 15000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-40
hmmm, are you using MPS or something non chlorine, that can have an affect on testing.. I am just not sure.. I use bromine and MPS about once a week..
I am going to a SWG for the spa this winter so no more bromine and MPS
Hopefully someone will have some more insight for you...
I am going to a SWG for the spa this winter so no more bromine and MPS
Hopefully someone will have some more insight for you...
Thanks for your reply. I appreciate your taking the time to ponder this ridiculousness of mine. I probably double dosed the spa not realizing it. Maybe the wife and myself both dosed it and just overdosed it. Im going to drain and clean it and hopefully it will be fine after that.
Or you can use hydrogen peroxide to lower it faster. You use the same amount of 3% hydrogen peroxide as the volume of 6% bleach in terms of FC -- that is, figure out the FC you want to drop, look up how much 6% bleach that would be (pretending you wanted to raise the FC by that amount), and then add that volume of 3% hydrogen peroxide to the spa to lower the FC.
Some good info there chem geek. Thanks. I'm finding that the FC is slowly falling. So I must have done something stoopid. I am thinking about just draining the tub at this point and doing the water change that is due. Is it necessary to do the pipe cleaning thing every time you do this or is that just overkill?
You don't have to do the Ahh-Some every time, especially if the water change is soon after the previous one, but for normal water changes it's not a bad idea to use it every time. You can see what comes out each time and decide based on that. Some spas get more material accumulated more quickly than others. Of course, if a spa wasn't consistently maintained, then the Ahh-Some should be used to remove any biofilms that may have formed.
Thanks Richard. We have consistently changed our water every 3 months. We have always used some sort of biofilm treatment in doing so. We in fact did two disinfection processes in a row the first time we put the tub back in operation after it had sat for some unknown period of time. But I have noticed that we have been getting nothing out of the pipes when do the disinfection process. It is only the wife and myself using the tub and that is usually once a day for 30 to 45 min. and we maintain the FC at about 6-7 so it seems to stay very clean. So I think that every other fill may be sufficient. Thanks for your reply.
So that sounds like 1 to 1.5 person-hours per day so if you were using the Dichlor-then-bleach method then if your spa is 350 gallons I'd expect you to be able to go (2/9) x (350) / (1 to 1.5) = 52 to 78 days between water changes so your changing every 3 months sounds about right unless I've got your spa volume way off.