Cedar hot tub w/vinyl liner but wood seats (CC question)

[PopcornSally]

I have my new cedar hot tub (1 month in operation) which has a vinyl liner that I thought would make water maintenance more straightforward.

My question: does the fact that there are 4 thick cedar slabs in the tub used for seating mean I will always have combined chlorine on my tests? Or do I really have a problem? Here are the water stats last test during slamming

FC 13.5
CC 2.5 (it's been closer to 1 most of the time)
pH 7.6
TA 90
CH 250
CYA 35
The water looks very clear.
(Taylor 2006 test kit)

Tub is holding ~440 gallons, kept covered at all times except at night when we use it, cartridge filter, temp. steady at 100 F, pump runs on low all the time except when we're in the tub, then it's on high.

Should I keep slamming or change the water and filter, maybe purge with Ahhsome? I think there is a problem because it seems like it's eating too much chlorine, like 6-8 ppm in 24 hours even when we don't get into the tub. Or is that OK?

We accidentally let the FC get close to or at zero a couple of weeks ago. All the plumbing is new and we put it together ourselves so if there is a biofilm, it happened after we bought it. I don't want to dissolve the wood but I also don't want to have a bacteria or algae problem.

Thanks, awesome pool people!!!

 

[Mdragger88]

Have u used any MPS? It shows up as cc’s on the test.
If not Maybe go for the Ahhsome purge.

 

[PopcornSally]

Nope. No MPS. I'm starting to think it must still be tannins from the wood. The higher I raise the chlorine, the higher CC gets. I might just refill it to make sure, though.

 

[Mdragger88]

I wonder what if any effects an Ahhsome purge might have on the wood. I can only assume it can’t be worse than extended periods of shock level Biofilms are biofilms right?

 

[PopcornSally]

Good question. I've decided to just wait and see what happens. There are no other signs of algae or bacteria. I really do wonder if it's just the wood consuming the chlorine. I'm just going to keep the level from going to zero (it eats about 6-7ppm every 24 hours) and do a refill in the next month or so. Maybe Ahhsome sometime in the future if I start getting nervous.

 

[PopcornSally]

Update: decided to do Ahh-some then drain and refill because it was eating more and more chlorine. Since this was my first experience with Ahh-some, I'm not sure how to interpret what I saw. A lot of white foam formed on top of the water with only a couple of flecks of green/gray. The filter cartridge was slightly discolored but it wasn't as bad as I feared.

One thing's for sure, the water smelled very strongly of something while I was emptying the tub after the purge--a mixture of chloramines and ??. Maybe that's normal for Ahh-some?

I'm refilling now and will report back what happens in case anyone searches for help with a tub like mine in the future.

 

[Dirk]

Are the benches removable? Taking them out would be one way to test your theory, if you can do without the tub for a few days...

 

[CrystalRiver]

I was also going to say to remove the wood if that's an option.

Are you letting the tub breathe? CCs in pools are burned off by UV. If you don't have a UV system in the hot tub and never leave it open to breathe, it could be that there's just no where for the CCs to go.

Hopefully your purge took care of everything and the problem doesn't come back.

 

[PopcornSally]

Good idea, Dirk & CrystalRiver. I hadn't thought of that. I could take the benches out but it would be a real pain. Plus there are the cleats they sit on which are also wood and not removable.

The water looks so much clearer, I now believe the wood is not the problem. I think there was actually something alive in there. I just put a tiny bit of dichlor in and my FC level is 3.2 with CC of only 0.4 which is the lowest it's been since opening day.

I'll be much more diligent with my FC from now on! And, good point, I will try to leave the lid open a bit to let the CCs air out.

We will probably get an SWCG eventually. We had one for our pool back in the day and it helped quite a bit although it didn't work perfectly.

I have another issue with my tub now but it's mechanical so I'll start a new thread for that.

I'll keep you posted.