Cedar tub saga

[ecstatic]

I would first like to thank the creators and contributors to this incredible knowledge base for all the soakers out there and a special thanks to moderators for making "the interest in Wood/cedar hot tub chemistry category" sticky! Without you I probably would have torched my cedar tub long ago. Now I can say I'm beginning to feel more confident in maintaining a finicky cedar tub and increasingly enjoying the soaking experience. 

I fell prey to the romance of owning a cedar tub with hours spent bathing in steamy heaven and jumped in over my head. I would now encourage interested buyers to think twice before investing investing in a wood tub. Thankfully the cedar tub knowledge base is growing. Unfortunately the Cedar tub threads are lacking the feedback from satisfied tub owners who could pass along some useful knowledge to the struggling lot. I hope that this is a good start to a manageable maintenance program specific to wood tubs and that it can grow with input from satisfied owners.

Some things we've learned so far:

Wood is an organic as much as is bather waste and is sensitive to sanitizers. A wood tub could be rendered useless in under 10 years, for some they have turned the cedar to pulp in under a year. Most user's experience little to no sanitizer the morning following a soak mostly due to residual FC eating into the wood. Cedar tub manufactures caution against chlorine levels above 2.5ppm. From my experience large or small additions of chorine give similar low FC readings the following day. In a fully decontaminated sanitized tub an addition of 3ppm dichlor post bathing will degrade to below .5ppm FC at the morning reading. I realize that this may not be adequate FC to counter the bathing load (keep in mind the tub maker said the tub would only require "a couple tsp of dichlor a week). I have recently added a Del Ozone Spa generator injected prior to a Del UVC-50 in order to span the periods of low FC which has greatly improved water quality. A flow switch allows the UVC to run any time pump is above 20gpm, the ozonator is triggered on for a pre and post bathing cycle. Still working out the kinks here. 

Ozone, UVC, AOP may be beneficial additions to our tubs. Though Dr Spa also urges caution with regard to unregulated ozone, that's why I chose to run ozone separately from the UVC as opposed to an all in one AOP since UVC is harmless to the cedar. The UVC-50 is perhaps an overkill for a 500 gal tub but it has 2" unions to allow the complete flow of water to pass through during filter cycles. This = peace of mind and sparkling water. Any guidance on ozone would be most appreciated regarding cycles and duration. Prior to choosing the ozone/UVC system the techs at DEL directed me to their in the field ozone "Guru" to discuss the build, he thought it appropriate. 

Some owners have burned their cedar tubs out with over sanitizing, particularly with bromine. Dr. Spa has cautioned against using anything but chorine because of Bromines strong residual leads to decay, still some manufacturers recommended bromine. Any further thoughts on Bromine?

Is decontamination along with high levels of sanitizer (50ppm FC) safe? I was very hesitant to super chlorinate my tub, but the results have been impressive. I have had a long standing funk to the water which did not dissipate with a spa flush along with lower 15ppm FC sanitizing fill. I finally threw in the towel with a fresh refill after decontamination with 50ppm Bleach with adjusted TA for 1 hour without any noticeable effect on the cedar. Good to know! For those of us who go for periods with zero FC it may be possible for bacteria to take root in the cedar. 

Now I am adding 3ppm Dichlor/Bleach religiously after post soak ozone cycle since ozone will not persist out in the tub. Next morning pretty consistent testing at .5ppm FC residual or lower, I add 2ppm FC to make it through to evening soak. I run a pre-soak ozone cycle on high for 1/2-1 hour while tub comes up to temp, then I am pretty sure FC is close to zero then another post-bathing ozone cycle for 1 hour.

I have been running the ozone during bathing, any thoughts on this? My logic in this being that there is more than 10' of plumbing post ozone injector along with the sizable UVC-50 chamber prior to tub jets. The ozone/UVC is on the filter bypass line and returns to main line prior to tub jets. Will ozone even make it out to the tub?

I'm in too far to quit now! I would like to hear your thoughts about maintaining low FC levels in our cedar tubs. It's inevitable that we will tank our FC from time to time and what about stepping away for a weekend or vacation? Could hire a hot tub sitter I guess. Is there any type of bleach injector possibility? Not sure if a SWG or salt system would be applicable in this situation of maintaining 1-2ppm FC. Browsing through posts I get that salt water spas are not encouraged. 

Best regards

Here is info on my spa:

500gal cedar Robert's Hot Tub

Pentair Intelliflo 3hp vsp; on bypass line in order of installation: Pentair C&C 75 filter; Pentair Mastertemp 125 heater; harwill flow switch; Flow Vis flow meter; Sunshine Pools Ionizer (not currently functional), Del Spa Ozone unit with Del mazzei injector and DEL manifold with manual valve; DEL UVC-50. Note the pump through the ionizer are located in my basement about 7' below waterline, ozone and UVC located in tub enclosure.

Attempt at Dichlor/bleach method and water chemistry per Nitro and Chem Geek

[Mendotub]

Hey there

im just getting a wooden tub and wondering how things evolved with your system, especially curious if you ended up installing a swg to go along with ionizer and ozonator. Thanks!