Indoor Hot Tub

[jeffboer]

The house we purchased in August has both a pool and 500 gallon indoor hot tub. I’m just getting acclimated to the TFPC method with the pool (working great so far!) so I’m now going to venture into tackling the indoor hot tub. Not sure what cleaning process was used previously, so I’ve purchased some Ahh-some gel to get the thing as clean as possible. I’ve read through some of the forum posts and have a general idea on how to handle the chemical balancing in the hot tub.

My question is in regards to CYA...the advice I’ve read says to raise CYA to around 30 with Dichlor then switch to LC. Being that the hot tub is indoors, is CYA necessary? If so, what is it’s purpose?

Thank you!

 

[jseyfert3]

It's highly recommended. It buffers the chlorine harshness. The target FC of 4-6 ppm with 30 ppm CYA has less active chlorine (HOCl) than even 0.2 ppm of FC with no CYA! This means it smells less, is easier on swimsuits/liners/skin.

I may be wrong on this, but what I think this means is that with no CYA, you could maintain the FC at 0.2 ppm and you'd have completely sanitary water. The problem is it's impossible to maintain 0.2 ppm of FC. It will go to zero, or poor circulation in one spot will mean a lack of sanitation there. This is why 1-3 ppm is recommended in pool literture. But with no CYA that is extremely harsh. Hence why TFP says use 30 ppm CYA, maintain 4-6 ppm FC, you'll get the more sanitizing power than 0.2 ppm FC yet it's easy to maintain.

Dig deeper here, if you wish: Pool Water Chemistry