What am I doing wrong?

[Transient]

In January, I bought a house that came with a hot tub (manufactured 2003). The previous owner said it had been sitting empty for a couple of years, but worked fine. Inside looked clean.

Filled it up, balanced the water and starting around 3 weeks it was forming a chemical smell and by 6 weeks it was unbearable (the mist from the jets would make you cough and sneeze). It was also burning through chlorine and so I got a Taylor K2006C testing kit. CC levels tested quite high (2.5).

I ran through some Ahh-some which produced a ring of gunk that looked like green toothpaste. Cleaned very thoroughly and refilled. After balancing and reheating, CC was nil.

This time around I have been adding liquid chlorine daily, but after after about 3 weeks, the chemical smell started to return, not as bad as before, but it was there. I tested and CC was showing around 0.5.
By week 4 it was again starting to cause us to cough and sneeze. CC tested at around 1.0, so I did a SLAM which after only a day and half brought CC down below 0.5, but the smell is still there. I also replaced the filter, just to be sure.

But after only another week, CC is testing above 1.0.

I'm at a loss as to what else to do. Should I SLAM it again? Run some Ahh-some through it again? Could the old filter have been bad and the new filter needs more than a week to clean it up? Something else?

 

[Ahhsomeguy]

You should do another purge or two to get more of the pipe-clinging bio-gunk released. This can peel off similar to an onion. One purge for a used tub setting empty for weeks, months or years has a lot of potential colonization to deal with. After this do another slam.

 

[Transient]

You should do another purge or two to get more of the pipe-clinging bio-gunk released. This can peel off similar to an onion. One purge for a used tub setting empty for weeks, months or years has a lot of potential colonization to deal with. After this do another slam.

Okay, thanks Ahhsomeguy, I'll give that a shot! Does it make sense to purge for more than 30 minutes? Maybe keep going until the gunk stops accumulating?

 

[5tan]

I ran the Ahhsome cleaner until the gunk stopped accumulating - I was scooping it out as it accumulated as well as wiping it off the sides. My jets turn off every 20 minutes and I was doing other things that afternoon, so it was on-off for closer to 4 hours before the gunk stopped accumulating.

Also added enough 10.8% pool chlorine to hit 20ppm FC at the beginning and the same amount halfway through. You want 20ppm chlorine in the water the whole time - Ahhsome physically dislodges chunks of biofilm, the chlorine is required to kill the dislodged bacteria, which consumes your FC quickly.

What I should have done before I drained was add another teaspoon or 2 and continued to run for another 30-60mins, as I'm not sure if the gunk stopped accumulating due to using up all the Ahhsome or due to no gunk being left in the system.

Another tip, dissolve the Ahhsome in hot water (in a jar or bucket) before pouring it into the spa, otherwise it's kinda slow to dissolve in the spa, even at normal heated spa temperatures.

I hope you removed your filter before running Ahhsome, otherwise the dislodged biofilms are gonna clog it up and breed in there. Should have tossed out the old filter, run Ahhsome with no filter in place, drain and clean, then plug in a new filter upon new fill. If reusing a possibly-contaminated filter, leave it in the footwell of the spa so that it gets washed with Ahhsome, then do a proper chemical soak of the filter overnight, hose off thoroughly, then reinstall + fill.

 

[Transient]

@5tan Thanks for the advice. I basically followed the Ahh-some directions, which said 30 minutes and then drain. It didn't mention anything about raising FC to 20, but that sounds like a good idea as does running it longer.

As for the filter, I did remove it before purging, but I left it floating in the tub (which is what the Ahh-some directions suggest). Now that I have a new filter, I'll probably remove it completely when I purge it next (this weekend, or maybe the following one).

The old filter actually looked clean both before and after Ahh-some. The manufacturer of the filter (Unicel) suggests soaking it in TSP for an hour, so I did that and a lot of milky stuff settled in the bottom of the sink, but I wasn't sure if it was the TSP or gunk coming out of the filter.