FC eaten up fast by clean, balanced hot tub

[jrmacleod]

Hi, I'm wondering why my free chlorine in my hot tub is heating up so quickly?

I've followed the dichlor/bleach method and have it balanced in line with recommended parameters. pH is a bit low at 7.0.

I top up the FC to 6.0 in a very clear tub and it consistently drops down to 1.0 within several hours even with no bathers.

Thoughts?

 

[jrmacleod]

Eating up the FC not heating up

 

[Oly]

If you keep a cover on your spa then you have a bio load that your FC is working on. How long since the water was changed? Since filter cleaned? Have you ever purged the plumbing system? Have you tested your CYA lately? List your spa type in your signature.

 

[jrmacleod]

Thanks Oly. I wondered about the cover having a bio load. Would cleaning the inside of the cover be a wise move and if so do you recommend any particular type of cleaning solution?

The water was changed a week ago and I've got it all balanced since then. We cleaned the filter at the same time.

I have not purged the plumbing system but am looking to order some Ahh-some to do that on next water change. Tub is only 2 seaons old and not noticing any film or "ring around the tub" as I've seen others mentioned when the plumbing is all gunked up with bio-film.

I have tested the CYA regularly and it is at 25, trying that out per the dichlor/bleach method.

I've updated my signature to have spa type now.

Thanks!

 

[Oly]

Sounds like you are properly managing your spa. I have come to learn that even new spas can harbor biofilm due to the wet testing following manufacture.
Research biofilms and look into Ahhsome for purging your plumbing. It can also be used to clean your cover. The discolored foam and residue ring is a result of using a strong surfactant to break down the protective biofilm during a purge.

 

[Backcountryski]

You have not cleaned the plumbing with Ahhsome, so would guess that is your culprit. Also, what is your CYA? If it is low or zero, with the hot water your chlorine will not last long.