Chlorine demand help!

[ShelleyN]

OK, so we bought a Sundance hot tub new.  Messed up on getting it balanced ASAP and keeping the chlorine up.  We got swimmer's rash about 2 weeks after getting it.  (Or the hot tub came with it-chicken or the egg at this point).

I purged it with Natural Chemistry Spa Purge.  Cleaned the interior with accelerated hydrogen peroxide (they use this in hospital baths) and bought a new filter. Balanced it with using strips (yes, I know bad idea).  It was flying through chlorine right off the fresh fill.  Chlorine demand 90% in 24 hours.   Did LOTS of research on here.   We never got in the tub on that fill.  Bought some Ahh-some and did another purge and 50ppm chlorine shock, drained and refilled.  The Ahh-some produced a small ring of green goo, but wasn't excessive. 

Bought the Taylor test kit recommended.  Balanced it.  

pH 7.6, Calcium 170, TA 70.  Brought the CYA up to 30ppm with dichlor.  Started bleach 2 days ago.  My chlorine demand is still crazy.  I shocked it last night to 12ppm with bleach (1.5cups in 420 gallon tub). Tonight it is 1ppm. And I think the only reason it is 1ppm is because I have an Ease ball in there.

What else can I do? 

Thanks for your thoughts.

[Ahhsomeguy]

Hi Shelly N.  I would recommend another purge.  Sometimes, plumbing build-up of organics can be challenging to dislodge and eliminate. You may want to let the Ahh-Some purge stay in the tub for an extended time, say 12 hours or so.  During this purge it would be helpful to intermittently turn the jets on and off, say once an hour.  Run the jets for 2 minutes, shut them off, an hour or so later do the same thing.

This can be a frustrating experience for any new hot tub owner.  You will succeed in your mission.  Stick with it and you will finally see that the dissipation rate for your sanitizer will go down.