Cleaned with Oh Yuk over a dozen times, still getting black stuff in the water

[HRK]

Hey guys, new member here.  I just purchased a house that has a hot tub.  I believe it's been sitting 6-12 months.  I cleaned with Oh Yuk thinking it could probably use a couple of cleanings, but here I am after over a DOZEN cleanings, and I'm still getting basically the same amount of black stuff out of the jets as the first time.  I'm guessing it's mold - a black dotted substance.  But there's alot of it built up on the sizes of the tub after each cleaning - probably a 1/2" wide line of this black stuff around the entire tub.  I'm following the instructions exactly, plus some - fill with water to the top of the jets, pour in 4oz Oh Yuk (I use 8oz every couple cleanings just to boost it), let run for a while (hour to an hour and a half each cleaning), drain, wipe residue, fill with water, run jets to rinse.  But every time I run jets to rinse, there's still black stuff in the water.  I'm not sure what else to do, is it time to call a professional to disassemble the entire mechanism?  Or do I just keep cleaning until it's gone? 

[Jacuzzi Jim]

 I have never heard or that product, but I wouldn't keep running through my spa.  It's possible what your are seeing is O-rings or heater element, impellers or who knows what else might be disintegrating and that's where this black stuff is coming from.  I would drain it again and run it for a couple of days with no yuk stuff, then throw some granular chlorine in there.  What ever was in there bacteria wise or water mold wise is probably gone.   To much of a good thing isn't always a good thing.   

[Starman]

OH Yuk and Ahhsom are the 2 top tub jet cleaners. Try leaving it sit overnight with the oh yuk also make sure you have the filters clean each time or throw them into the water and rinse after.
I have both but have only used Ahhsome it works very well

[Sam]

I agree that ahh-some works really well.  If it's that bad, I recommend putting in the ahhh-some and running for 30 minutes, then add a huge dose of chlorine to get the chlorine level up to 100ppm and leave it run a day or 2.  That combo will usually get rid of most issues.

[someguy]

Hello HRK:  Thank you for bringing up a very visible problem that is encountered by many hot tub owners.  Using the Oh Yuk is NOT degrading your o'rings or pump parts.  The black/brown particulates you see is biofilm and the plethora of other gunk and build-up that has attached and colonized inside your hot tub plumbing.  This buildup is very difficult to break up in one or two purges, hence, your need to do additional cleanings.  Frustrating I know!  The Oh Yuk is doing what it is supposed to do.  It is true that the Ahh-Some cleaner is very popular and is used by many hot tub owners since it is the only EPA Registered hot tub plumbing cleaner and has science to back up the claims. Both of these cleaners work.  Keep at it and you will be able to claim victory.  Adding large amounts of any sanitizer will NOT speed up the cleaning process.  Chlorine does NOT remove biofilm.  Please google biofilm in hot tubs and you'll see what you are dealing with.